The economics of robot manufacturing is driving us toward situations in which a single human operator will be expected to split attention across multiple semi-autonomous vehicles, and remotely intercede if necessary. We present an analysis of such situations, with the goal of creating decision aids. Toward this end, the concept of special regions is introduced. In one set of situations special regions designate areas that are dangerous, and require teleoperation. We show how to move through single route and multi-route situations, and prove the later problem NP-Complete. In another set of situations, special regions can be used to represent areas outside direct radio contact. We present a way to minimize communication distance and plan for interventions. We relate our findings to concepts of neglect time, interaction time, and fan-out. We discuss a measure of effective fan-out for transportation tasks, and present simulation results. The work has potential impact to those engaged in emergency response and search and rescue.

The goal of this study is to determine the effect of `maintain position' and `relax' tasks on the dynamic of the foot while manipulating a gas pedal. The foot is viewed as a mass-spring-damper system, of which the visco-elasticity can be altered by reflexive feedback and muscle (co-)contraction. The dynamic properties of the foot are described by the mechanical admittance, which determines the foot position as a dynamic function of an external force perturbation. It is hypothesized that humans will change their admittance based on task perception. Experiments were done to estimate the endpoint foot admittance with Frequency Response Functions (FWs). An experimental setup that can simulate a gas pedal with different static and dynamic properties was used to apply continuous force perturbations to the foot. Eight subjects were instructed to either minimize the resulting pedal deviations (`maintain position 3 or do nothing and just rest their foot on the pedal (`relax'). The force perturbation, pedal position, and reaction force were measured, and transformed tot the frequency domain to estimate the closed-loop admittance. All subjects showed a considerable difference between the two tasks, confirming the hypothesis that drivers change the dynamics of their foot to best accomplish a perceived task.

The goal of this study is to determine the effect of amplitude and frequency of force sinusoids on force perception of the foot, in order to design an effective haptic feedback system for gas pedals. Eight subjects were asked to push a gas pedal to a constant workpoint position against a background force of 25 N Force perception was determined for three frequencies and three types of footwear by requiring subjects to respond with `yes' or `no' after each force sinusoid. Psychometric functions were calculated from the data, relating the ratio of yes answers (averaged over all subjects) to the amplitude of the force sinusoid. Although large standard deviations were found for low ratios, a statistically signifcant Just Noticeable Difference (JND) could be determined for the upper boundary of perception. Increasing the frequency of the stimulus decreased the JND. Footwear was shown to have a substantial impact on the JND at all frequencies, the largest effect occurring at the lowest frequency.

Instrument controls in motor vehicles have haptic properties (force and compliance) designed to enhance the ease of use. In conventional control knobs, these properties are obtained mechanically via springs, detents, hard stops and the like. The work reported here concerns the use of a single force-feedback knob to emulate the feel of various conventional control knobs, thus retaining their desirable haptic properties while allowing multiple functions to be controlled through one device. Compared to existing haptic knobs, this one is novel in its use of a brake to provide high torque capability in a small volume.

The design of interfaces for automotive information systems is a critical task. In fact, such design must take into account that user is busy in the primary driving task, and any visual distraction determined by telematics systems can cause serious safety problems. To limit such distraction and enhance safety, in this paper we propose a novel multimodal user interface. The key element of the proposal is a new interaction device, named Handy, conceived to exploit the drivers tactile channel to minimize the workload of visual channel. Moreover Handy is suitably integrated with the graphical user interface, which is characterized by a reduced number of choices for each state and has been designed in agreement with the self-revealing approach.

Rapid and accurate visuomotor coordination requires tight spatial and temporal sensorimotor synchronization. The introduction of a sensorimotor or intersensory misalignment (either spatial or temporal) impairs performance on most tasks. For more than a century, it has been known that a few minutes of exposure to a spatial misalignment can induce a recalibration of sensorimotor spatial relationships, a phenomenon that may be referred to as spatial visuomotor adaptation. Here, we use a high-fidelity driving simulator to demonstrate that the sensorimotor system can adapt to temporal misalignments on very complex tasks, a phenomenon that we refer to as temporal visuomotor adaptation. We demonstrate that adapting on a single street produces an adaptive state that generalizes to other streets. This shows that temporal visuomotor adaptation is not specific to a single visuomotor transformation, but generalizes across a class of transformations. Temporal visuomotor adaptation is strikingly parallel to spatial visuomotor adaptation, and has strong implications for the understanding of visuomotor coordination and intersensory integration.

Three on-road studies were conducted to determine how headway maintenance and collision warning displays influence driver behavior. Visual perspective, visual perspective with a pointer, visual perspective combined with an auditory warning, discrete visual warning, and discrete auditory warning were assessed during both coupled headway and deceleration events. Results indicate that when drivers are provided with salient visual information regarding safe headways, they utilize the information and increase their headway when appropriate. Auditory warnings were less effective than visual warnings for increasing headways but may be helpful for improving reaction time during events that require deceleration. Drivers were somewhat insensitive to false alarm rates, at least during short-term use. Finally, and most important, driver headway maintenace increased by as much as 0.5 s when the appropriate visual display was used. however, a study to investigate the long-term effects of such displays on behavior is strongly recommended prior to mass marketing of headway maintenance/collision warning devices.

Sensory overloaded environments present an opportunity for innovative design in the area of Human-Machine Interaction. In this paper we study the usefulness of a tactile display in the automobile environment. Our approach uses a simple pneumatic pump to produce pulsations of varying frequencies on the driver's hands through a car steering wheel fitted with inflatable pads. The goal of the project is to evaluate the effectiveness of such a system in alerting the driver of a possible problem, when it is used to augment the visual display presently used in automobiles. A steering wheel that provides haptic feedback using pneumatic pockets was developed to test our hypothesis. The steering wheel can pulsate at different frequencies. The system was tested in a simple multitasking paradigm on several subjects and their reaction times to different stimuli were measured and analyzed. For these experiments, we found that using a tactile feedback device lowers reaction time significantly and that modulating frequency of vibration provides extra information that can reduce the time necessary to identify a problem.

The bulk of current haptics human-factors research focuses on mapping basic human perceptual limits. However, many realistic applications demand a better understanding of how to construct more life-like but often less controllable experiment scenarios. In this paper, we study this problem in the context of advanced automobile interfaces. We employ a throttle pedal with programmable force feedback to indicate potentially undesirable situations in the external environment and to gently but steadily guide the driver away from them. We have found evidence that within this scenario, errors in such a warning signal can have a negative effect on the behavior of the driver within the conditions studied. These experiments required a complex protocol and necessarily permitted a variety of participant tactics. Post-experiment analysis revealed that very subtle variations in participant instruction produced large differences in tactics and consequent experiment outcome.

During manual steering of a vehicle, the information to the driver is restricted by his perception and recognition. The driver may lose such information under severe weather conditions. Look-ahead information has been shown to have great importance for vehicle steering problems. A supplementary visual display has been developed to provide both the fiture road information and the future position of the vehicle based on current vehicle state and steering input for safer driving. A state observer is proposed to estimate the current vehicle state. Both the current steering input and the estimated vehicle state are utilized to predict the future position of the vehicle at a prescribed look-ahead distance. Integration of the vehicle trajectory into future is avoided by an approximation method, which can be applied in real-time implementation.

In this paper, a paradigm for shared control is described in which a machine's manual control interface is motorized to allow a human and an automatic controller to simultaneously exert control. The manual interface becomes a haptic display, relaying information to the human about the intentions of the automatic controller while retaining its role as a manual control interface. The human may express his control intentions in a way that either overrides the automation or conforms to it. The automatic controller, by design, aims to create images in the mind of the human of fixtures in the shared workspace that can be incorporated into efficient task completion strategies. The fixtures are animated under the guidance of an algorithm designed to automate part of the human/machine task. Results are presented from 2 experiments in which 11 subjects completed a path following task using a motorized steering wheel on a fixed-base driving simulator. These results indicate that the haptic assist through the steering wheel improves lane keeping by at least 30% reduces visual demand by 29% (p<0.0001) and improves reaction time by 18 ms (p=0.0009).

We report two experiments designed to investigate the potential use of vibrotactile warning signals to present spatial information to car drivers. Participants performed an attention-demanding rapid serial visual presentation (RSVP) monitoring task. Meanwhile, whenever they felt a vibrotactile stimulus presented on either their front or back, they had to check the front and the rearview mirror for the rapid approach of a car, and brake or accelerate accordingly. We investigated whether speeded responses to potential emergency driving situations could be facilitated by the presentation of spatially-predictive (80% valid; Experiment 1) or spatially-nonpredictive (50% valid; Experiment 2) vibrotactile cues. Participants responded significantly more rapidly following both spatially-predictive and spatially-nonpredictive vibrotactile cues from the same rather than the opposite direction as the critical driving events. These results highlight the potential utility of vibrotactile warning signals in automobile interface design for directing a drivers visual attention to time-critical events or information.

The potential use of non-visual warning signals to present spatial information to car drivers has been successfully demonstrated in several recent studies (Ho & Spence, submitted, in preparation; Ho, Tan, & Spence, submitted). Among the three types of spatial warning signals investigated (namely auditory, visual, and vibrotactile), spatial vibrotactile cues were found to be particularly effective in directing a driver's visual spatial attention to potentially dangerous events on the road. We conducted the present study in order to examine the factors governing the relative effectiveness of auditory, visual, and vibrotactile warning signals. The speeded discrimination of warning signals presented in the various different modalities was investigated in order to explore whether the differences found in our previous research were a result of the relative speed with which people can detect warning signals presented in a given modality, or whether they were attributable to differences in the efficacy with which people can relate the warning signal to the subsequent visually-specified target driving events.

This article reports the development of a multidimensional measure of subjective fatigue states, and its associations with personality in an experimentally-controlled context. In a study of simulated driving, 256 subjects completed a new 24-item fatigue scale as well as other subjective state measures, before and after performing a fatiguing drive. An item factor analysis identified four correlated dimensions: visual fatigue, muscular fatigue, boredom and malaise. The scales were sensitive to increased fatigue following the fatiguing drive, and showed a high degree of internal consistency. The fatigue scales correlated substantially with general state measures, such as mood and motivation. A factor analysis of fatigue and other state scales identified second-order factors of task disengagement (including boredom), physical fatigue (including the other three fatigue scales), and a distress factor. The fatigue scale was also correlated with the EPQ-R and with a measure of traits related specifically to driving, the Driving Behaviour Inventory (DBI), which includes a Fatigue Proneness scale. Bivariate and multivariate analyses showed that Fatigue Proneness was the strongest single predictor of task-induced fatigue symptoms, as predicted from an interactionist analysis of relationships between traits and states. However, the relationship between traits and states associated with fatigue was complex, and other EPQ-R and DBI traits, including neuroticism, were independently associated with fatigue.

The research reported in this article considers the effects of automating driver's control tasks. Driving can be broken down into 3 general subtasks: navigation, control, and hazard avoidance. Control can be further subdivided into lateral control (positioninlane)and longitudinal control (speed and leading headway). Lateral control can be automated by an active steering (AS) system, and longitudinal control can be automated by an adaptive cruise control (ACC) system. Previous research has used driving simulators to consider the effects of driver workload and the ability to reclaim control with these systems. There are, however, some questions about the validity of driving simulators, and this research sought to validate a driving simulator. This was achieved by comparing responses on a secondary task and driving style questionnaire in both a road car and a driving simulator. When validity was established, a comparison of 4 levels of automation was undertaken: manual, ACC, AS, and ACC plus AS. The results showed no reduction in workload associated with ACC over manual driving, but reduction in workload associated with AS and further reduction in workload associated with ACC plus AS. Despite these reductions in workload, there were no adverse affects on normal driving performance. However, the presence of vehicle automation seemed to make drivers less likely to reclaim control in an emergency-braking scenario.

When humans interface with machines, the control interface is usually passive and its response contains little information pertinent to the state of the environment. Usually, information flows through the interface from human to machine but not so often in the reverse direction. This work proposes a control architecture in which bi-directional information transfer occurs across the control interface, allowing the human to use the interface to simultaneously exert control and extract information. In this alternative control architecture, which we call shared control, the human utilizes the haptic sensory modality to share control of the machine interface with an automatic controller. We present a fixed-base driving simulator experiment in which subjects take advantage of a haptic steering wheel, which aids them in a path following task. Results indicate that the haptic steering wheel allows a significant reduction in visual demand while improving path following performance.

Although it is not always possible to derive from statstics the causes of an accident, data clearly show that they are mostly due to a lack of driver's perception, with high social costs for society (direct and not). Therefore, a strong integration among all the actors involved (that is the drivers, the vehicle or technical system in general and the environment) is really necessary. From first years of 80's, there has been a shift in sysfem concept design, moving from a technological approach towards a human centred design approach. Under this point of view, if is necessary to take into account on one side the user's needs in the design process of a certain system, and on the other side also the ``machine needs''. Thus, this paper aims at presenting such types of needs as well as the mutual interaction between machine and users and both with the surrounding environment.

This paper describes the potential of using vibro-tactile displays for automobile drivers. Technological developments in the field of driver support systems and tactile displays, combined with the ever increasing need to enlarge the capacity of the driver's information channel, form the reason to review the possibilities of in-car tactile displays and to identify some promising applications. In the second part of the paper, we describe a feasibility study in which we tested an in-car tactile display in a driving simulator. The results show that the tactile navigation display resulted in better performance compared to a visual display, and that it reduces the driver's workload. This study gives a first indication that employing the tactile modality may be a major step to accomplish safety improvements.

A comparison of walking against vertical (gradient) and horizontal (trailing weight) forces was made during steady-rate exercise at 0,250, 500, and 750 kg.m/min with speeds of 3.0, 4.5, and 6.0 km/h. In all cases exponential relationships between energy expenditure (calculated from the steady-rate respiration) and increasing work rate and speed were observed which indicated that muscular efficiency during walking is inversely related to speed and work rate. ``Work'' (level, unloaded walking as the baseline correction), ``delta'' (measured work rate as the baseline correction), and ``instantaneous'' (derived from the equation describing the caloric cost of work) efficiencies were computed. All definitions yielded decreasing efficiencies with increasing work rates. At work rates above 250 kg' m/min the curves describing the relationship between energy expenditure and work rate were parallel for vertical and horizontal forces, indicating equivalent efficiencies in this range. Only the delta and instantaneous definitions accurately described these relationships for vertical and horizontal work. Determinations of combined work loads (gradient plus trailing weight) were made and the energy costs of both types of work found to be additive.

The use of self-selected intensities of exercise may increase adherence to exercise programs by allowing the participant more freedom to choose activities that are enjoyable. However, self-selected intensities may vary across exercise modes, and participants may not choose an intensity that is adequate to produce health benefits. The purpose of this study was to determine influence of exercise mode on self-selected exercise intensities. Eighteen subjects (12 men and 6 women) between the ages of 18 and 25 participated in this study. Preferred intensity tests were performed for 3 modes of exercise (treadmill, cycle ergometer, and stairstepper). VO2 values were obtained continuously and 1-minute averages were recorded at minutes 5, 10, 15, and 20 for each submaximal test. Comparisons were made using a repeated-measures analysis of variance (mode, time, mode time). Scheffe's F test was used to test simple effects. There was a significant increase in the relative VO2 for all 3 modes of exercise across the 20-minute trials (p 0.0001). Relative VO2 (%VO2peak) increased from 52.20 to 64.71% for cycle exercise, 43.27 to 63.25% for the treadmill, and 47.16 to 61.17% for stairstepping. The average relative VO2 for the cycle ergometer (60.40 +/- 15.55%) was significantly higher (p 0.02) than both the treadmill (53.65 +/- 18.36%) and stairstepper (54.66 +/- 11.98%). Relative heart rate (HR) (%HRR) for the stairstepper (80.21+/- 9.67%) and the cycle ergometer (80.03 +/- 10.59%) were significantly higher than the treadmill (74.77 +/- 13.13%) (P 0.0003). There were no significant differences in rating of perceived exertion (RPE) among the 3 modes of exercise. Similar RPE values were reported for the stairstepper (12.79 +/- 2.97), cycle ergometer (12.57 +/- 2.90), and the treadmill (12.50 +/- 2.87). The results indicate that subjects allowed to choose exercise intensity by self-selection chose work rates that were within the moderate range of American College of Sports Medicine guidelines of 50--85% VO2max for treadmill, cycle ergometer, and stairstepping exercise.

The primary purpose of this study was to determine if the aerobic demand for production of specified power outputs is altered by distribution of work between the arms and legs compared with when all the work is performed by the legs. Because of the important exercise training implications, a secondary purpose of this study was to determine if the exercising muscle mass affects the cardiorespiratory demands at specified rating of perceived exertion (RPE) levels and blood lactate concentrations. Nine healthy adults completed leg cycling and combined arm and leg exercise on an Airdyne using a discontinuous protocol. Repeated measures ANOVA revealed that oxygen uptake for the combined arm and leg exercise averaged 0.04 l - min)1 greater (p < 0.05) than for leg cycling at the same external power outputs. However, RPE levels at specified power outputs were lower (p < 0.05) with combined arm and leg exercise than leg cycling. At specified RPE levels and blood lactate concentrations, oxygen uptake and heart rate values were higher (p < 0.05) for combined arm and leg exercise than leg cycling. From these findings we conclude that: (1) the addition of arm exercise to leg cycling results in a reduction in RPE, but a minimal increase in oxygen consumption to perform a given power output, and (2) if training intensity is established by RPE or blood lactate concentration, use of a muscle mass larger than that used in leg cycling should allow a greater cardiorespiratory training effect.

The power output of an athlete decreases rapidly with time. The author describes ditferent ways of measuring power output, including a unique method, developed at Loughborough University for measuring the power developed by a sprint runner.

Purpose: Based on the resistance-rpm relationship for cycling, which is not unlike the force-velocity relationship of muscle, it is hypothesized that the cadence which requires the minimal muscle activation will be progressively higher as power output increases. Methods: To test this hypothesis, subjects were instrumented with surface electrodes placed over seven muscles that were considered to be important during cycling. Measurements were made while subjects cycled at 100, 200, 300, and 400 W at each cadence: 50, 60, 80, 100, and 120 rpm. These power outputs represented effort which was up to 32% of peak power output for these subjects. Results: When all seven muscles were averaged together, there was a proportional increase in EMG amplitude each cadence as power increased. A second-order polynomial equation fit the EMG:cadence results very well (r2 0.87-- 0.996) for each power output. Optimal cadence (cadence with lowest amplitude of EMG for a given power output) increased with increases in power output: 57 3.1, 70 3.7, 86 7.6, and 99 4.0 rpm for 100, 200, 300, and 400 W, respectively. Conclusion: The results confirm that the level of muscle activation varies with cadence at a given power output. The minimum EMG amplitude occurs at a progressively higher cadence as power output increases. These results have implications for the sense of effort and preferential use of higher cadences as power output is increased.

A cycle ergometer was modified to measure power (P) with resistance provided solely by the moment of inertia (I) of the flywheel. P was calculated as the product of I, angular velocity ([omega]), and angular acceleration([alpha]). Flywheel [omega] and [alpha] were determined by means of an optical sensor and a micro-controller based computer interface which measured time(+/-1 microsecond) and allowed P to be calculated instantaneously(PI) every 3[degrees] of pedal crank rotation or averaged over one complete revolution of the pedal cranks (PREV). Values for maximum P were identified from each bout (PI max and PREV max). Mechanical calibration of torque via a resistive strap proved this method to be both valid and accurate. Thirteen active male subjects performed four bouts of maximal acceleration lasting approximately 3-4 s with 2 min resting recovery. The mean coefficient of variation for PREV max was 3.3 +/- 0.6% and the intraclass correlation was 0.99. PREV max averaged 1317+/- 66 W at 122 +/- 2 rpm, and PI max averaged 2137 +/- 101 W at 131 +/- 2 rpm. PREV max and PI max were highly correlated (r = 0.86 and r = 0.80 respectively, P < 0.002) with estimated lean thigh volume. Therefore, the inertial-load method provides a valid and reliable determination of cycling power in one short exercise bout.

A novel apparatus, composed by a controllable treadmill, a computer, and an ultrasonic range finder, is here proposed to help investigation of many aspects of spontaneous locomotion. The acceleration or deceleration of the subject, detected by the sensor and processed by the computer, is used to accelerate or decelerate the treadmill in real time. The system has been used to assess, in eight subjects, the self-selected speed of walking and running, the maximum ``reasonable'' speed of walking, and the minimum reasonable speed of running at different gradients (from level up to 25%). This evidenced the speed range at which humans neither walk nor run, from 7.2 0.6 to 8.4 1.1 km/h for level locomotion, slightly narrowing at steeper slopes. These data confirm previous results, obtained indirectly from stride frequency recordings. The self-selected speed of walking decreases with increasing gradient (from 5.0 0.8 km/h at 0% to 3.0 0.9 km/h at 25%) and seems to be 30% higher than the speed that minimizes the metabolic energy cost of walking, obtained from the literature, at all the investigated gradients. The advantages, limitations, and potential applications of the newly proposed methodology in physiology, biomechanics, and pathology of locomotion are discussed in this paper.

Robotic devices hold much promise for use as rehabilitation aids but their success depends on identifying effective strategies for controlling human--robot interaction forces. We developed a robotic device to test a novel method of controlling interaction forces with the intent of improving force symmetry in the limbs. Users perform lower limb extensions against a computer-controlled resistive load. The control software increases resistance above baseline in proportion to lower limb force asymmetry (balance between left and right limb forces). As a preliminary trial to test the device and controller, we conducted two experiments on neurologically intact subjects. In experiment 1, one group of subjects received symmetry-based resistance while performing lower limb extensions (n = 10). A control group performed the same movements with constant resistance (n = 10). The symmetry-based resistance group improved lower limb symmetry during training (ANOVA, p<0.05), whereas the control subjects did not. In experiment 2, subjects (n = 10) successfully used symmetry-based resistance to alter their lower limb force production towards a target asymmetry (ANOVA, p<0.05). These studies suggest that symmetry-based resistance may hold rehabilitation benefits after orthopedic or neurological injury. Specifically, performing strength training therapy with this controller may allow hemiparetic individuals to focus better on increasing strength and neuromuscular recruitment in their paretic limb while experiencing symmetric limb forces.

Aspects of anaerobic and aerobic energy conversion are investigated using a mathematical model of running in conjunction with world-record statistics. Analysis of the data shows that over distances from 1500 to 10,000 m the anaerobic energy utilised is constant and independent of running distance. This result is consistent with the view that the full potential of the anaerobic capacity is available for conversion during extended periods of running; the opinions of Gollnick and Hermansen (1973) and Peronnet and Thibault (1989) that the anaerobic energy contribution declines with race duration are not corroborated. The analysis supports the finding of Peronnet and Thibault (1989) that, for running times below about 1"420 s, the maximum sustainable aerobic power is constant, and that for larger 1 it then declines progressively. The present analysis shows it falls by some 4.5% over 10,000 m, 1+1600 s, indicating that in establishing current world records at 5000 and 10,000 m athletes did not rely solely on glycogen as the source of aerobic metabolism; limited use was made of free fatty acids. For elite male runners, the anaerobic capacity and maximal aerobic power are evaluated as 1570 J/ kg and 27.1 W/ kg, respectively.

The IM4Sports music system helps exercisers select music that suits their training programs, reflects and guides sport performance, and collects data for adapting training programs and music selections.

A multitude of indoor exercise machines are promoted for improving aerobic fitness and for controlling body weight. Previous investigations have performed physiological comparisons of some of these exercise machines. However, a comprehensive comparison of the aerobic and energy demands relative to level of perceived exertion has not been performed. Such a comparison is important because the intensity of exercise is often determined by the perceived effort. The primary purpose of this study was to compare 6 commonly used, popular indoor aerobic exercise machines to determine which would elicit the greatest rate of energy expenditure at specified levels of perceived exertion.

Ever wondered if your glutes, lats and pecs are getting the workout they deserve? When your exercise equipment is retrofitted with the Mytrak Health System, you'll know for sure. Developed for the health club market by InCorp Ventures Inc. (mytrakhealth.com) of Mississauga, ON, the system adds intelligence and automation to exercise equipment.

This paper describes the simulation of stairs on a treadmill style locomotion interface using torso force feedback. The active mechanical tether of the Sarcos Treadport locomotion interface applies a specialized force profile to simulate the forces of stair walking. The biomechanics of subjects walking on real stairs versus walking under the specialized force prolile were compared. It was found that the tether force was able to adjust the subject's motion from standard slope walking towards that of stairs.

The control of a one degree of freedom exercise machine is considered. The control objective consists in making the human user exercise in a manner that maximizes his consumption of power. The optimality condition is determined by the muscle mechanics which is assumed to satisfy a force-position-velocity relationship. In general, the parameters of this relationship are unknown and vary with the configuration of the exercise machine. As a consequence, the control scheme must simultaneously i) identify the user's strength characteristic, ii) optimize the controller, and iii) stabilize the system to the estimated optimal state. In this paper we present control systems in the form of a nonlinear dynamic or static dampers that make the controlled system interact passively with the user. Adaptive and self-optimizing control strategies are discussed, which achieve the control objectives described above. Results of a clinical study are presented which corroborate many of the assumptions used in this paper and verify the efficacy of the proposed control schemes.

This article discusses the dynamics and design of multiple-degree-of-freedom robotic systems built as general purpose exercise machines for the human arm. These machines may be programmed to give the human arm the sensation of forces associated with various arbitrary maneuvers. As examples, these machines can give the human the sensation that he/she is maneuvering a mass, or pushing onto a spring or a damper. In general, the machines may be programmed for any trajectory-dependent force. To illustrate and verify the analysis of these machines, a two-degree-of-freedom electrically-powered exercise machine was designed and built at the Motion Control Laboratory of the University of California-Berkeley.

In a self-optimizing control problem, it is desired that the plans with a priori unknown parameters perform a task that optimizes a performance index. If the optimal task can be specified explicitly, an adaptive controller can often be designed to enable that task to be performed. However in many cases, the optimal task cannot be explicitly specified becausee it may depend on the unknown plan's parameters, and must also be determined explicitly on-line. In the context of intelligent controllers for exercise machines, the resistive/assistive force on the machine is manipulated to cause the user of the machine to maximize his/her mechanical power output while exercising. The optimal manner in which the user exercises is represented by a velocity field which is a functio of the individual's unknown biomechanic characteristics. The proposed self-optimizing control approach combines i) a continuous state adaptive controller which enables an arbitrary explicitly specified task to be performed; and ii) a finite state excitation supervisor which switches the desired task between a training task and the estimated optimal task based on current system parameter estimates. Depending on the switching scheme chosen, it is shown that the user will asymptotically either execute the true optimal exercise with probability one or operate close to it. Experimental results of the implementation verifies the efficacy of the design.

In order to achieve the general exercise objectives of increasing i) strength, ii) stamina, and iii) cardiovascular workout, a proper exercise regime has to achieve certain tradeoffs specific to the individual's muscle mechanics and the fatigue states. An adaptive approach is proposed to control a 1 degree of freedom (DOF) exercise machine in which the exercise regime is modified according to the estimates of the force-velocity relationship (Hill's curve) of the muscle. An optimal velocity profile is determined from the Hill's curve via a class of power related criteria. The adaptive controller simultaneously identifies the Hill's curve, and causes the user to operate at the estimated optimal velocity profile.The controller always interacts with the user passively. It is believed that the adaptive controller is able to modify the exercise regime accordingly an fatigue acts in. Stability and convergence results have been rigorously proven and in here some preliminary experimental results are presented.

The control of a one degree of freedom exercise machine is considered. The control objective is to cause the human user to exercise at a rate which optimizes a prescribed weigthed power criterion. The optimality condition is determined by the muscle mechanics which is assumed to satisfy a force-velocity relationship. In general, the parameters of this relationship are unknown and vary with the configuration of the exercise machine. As a consequence, the control scheme must simultaneously i) identify the parameters, ii) optimize the controller, and iii) stabilize the system to the estimated optimal states. In this paper we derive a controller which is in the form of a nonlinear dynamic damper and makes the controlled system interact passively with the user. Assuming that the human's force-velocity muscular biomechanics relationship is known, this controller allows the user to excercise in an optimal manner.

This is the first part of a two-part paper on the design of intelligent controllers for a class of exercise machines. The control objective is to cause the user to exercise in a manner which optimizes a criterion related to the user's mechanical power. The optimal exercise strategy is determined by a biomechanical behavior of the individual user, which is assumed to satisfy an affine force--velocity relationship dependent on the body geometric configuration. Consequently, the control scheme must simultaneously: 1) identify the user's biomechanical behavior; 2) optimize the controller; and 3) stabilize the system to the estimated optimal states. Moreover, to ensure that the exercise machine is safe to operate, the control system guarantees that the interaction between the exercise machine and the user is passive. In this first part of the paper, we formulate the control problem and propose a controller structure which satisfies the safety requirement and is capable of causing the user to execute an arbitrary exercise strategy if the user's biomechanical behavior is known. The controller is of the form of a dynamic damper and can be implemented using only passive mechanical components. Part II of this paper is concerned with the self-optimization problem, in which both the determination of the optimal exercise strategy and the execution of that strategy, when the user's biomechanical behavior is unknown, must be considered.

This is the second part of a two-part paper on the design of an intelligent controller for a class of exercise machines. The control objective is to cause the user to exercise in a manner that optimizes a criterion related to the user's mechanical power. The optimal exercise strategy is determined by an a priori unknown biomechanical behavior, called the Hill surface, of the individual user. Consequently, the control scheme must simultaneously: 1) identify the user's biomechanical behavior; 2) optimize the controller; and 3) stabilize the system to the estimated optimal states. In Part I of this paper, a dynamic damping controller was proposed which satisfies the safety requirement and is capable of causing the user to execute an arbitrary exercise strategy if the user's biomechanical behavior is known. In this second part of the paper, we address the self-optimization problem in which both the determination and the eventual execution of the optimal exercise strategy are accomplished, when the user's biomechanical behavior is unknown. This is achieved by a combination of an adaptive controller and a reference generator. The latter switches the desired exercise strategy between a training strategy and the estimated optimal strategy. Depending on the switching scheme chosen, it is shown that, asymptotically, the user will either execute the optimal exercise with probability one or operate close to it. Experimental results of the overall system verify the efficacy of the design.

Purpose: Based on the resistance-rpm relationship for cycling, which is not unlike the force-velocity relationship of muscle, it is hypothesized that the cadence which requires the minimal muscle activation will be progressively higher as power output increases. Methods: To test this hypothesis, subjects were instrumented with surface electrodes placed over seven muscles that were considered to be important during cycling. Measurements were made while subjects cycled at 100, 200, 300, and 400 W at each cadence: 50, 60, 80, 100, and 120 rpm. These power outputs represented effort which was up to 32% of peak power output for these subjects. Results: When all seven muscles were averaged together, there was a proportional increase in EMG amplitude each cadence as power increased. A second-order polynomial equation fit the EMG:cadence results very well (r2 0.87-- 0.996) for each power output. Optimal cadence (cadence with lowest amplitude of EMG for a given power output) increased with increases in power output: 57 3.1, 70 3.7, 86 7.6, and 99 4.0 rpm for 100, 200, 300, and 400 W, respectively. Conclusion: The results confirm that the level of muscle activation varies with cadence at a given power output. The minimum EMG amplitude occurs at a progressively higher cadence as power output increases. These results have implications for the sense of effort and preferential use of higher cadences as power output is increased.

A novel apparatus, composed by a controllable treadmill, a computer, and an ultrasonic range finder, is here proposed to help investigation of many aspects of spontaneous locomotion. The acceleration or deceleration of the subject, detected by the sensor and processed by the computer, is used to accelerate or decelerate the treadmill in real time. The system has been used to assess, in eight subjects, the self-selected speed of walking and running, the maximum ``reasonable'' speed of walking, and the minimum reasonable speed of running at different gradients (from level up to 25%). This evidenced the speed range at which humans neither walk nor run, from 7.2 0.6 to 8.4 1.1 km/h for level locomotion, slightly narrowing at steeper slopes. These data confirm previous results, obtained indirectly from stride frequency recordings. The self-selected speed of walking decreases with increasing gradient (from 5.0 0.8 km/h at 0% to 3.0 0.9 km/h at 25%) and seems to be 30% higher than the speed that minimizes the metabolic energy cost of walking, obtained from the literature, at all the investigated gradients. The advantages, limitations, and potential applications of the newly proposed methodology in physiology, biomechanics, and pathology of locomotion are discussed in this paper.

This paper discusses the design of a compatible controller for the Expert-Based Variable Resistance/Assistance (EVRA) exercise machine that removes the shortcomings found in the currently available constant-resistance and other variable resistance exercise machines. A mathematical model of the EVRA prototype is used to simulate its dynamic behavior using the Matlab/Simulink software package. The feed-back controller generates control signals to engage an electric motor to provide either assistance/resistance as per demand. The proposed controller is able to detect significant changes in the kinematic and neurophysiological movement profiles, compare this data with an existing database and then provide the appropriate level of mechanical assistance to the moving limb to maintain a coordinated movement profile. A comparative study on the various types of controllers (such as PI and Neuro-controllers) is also presented.

In this dissertation, the design of resistance controllers for exercise machines is considered. Whereas most exercise machines perform a preprogrammed routine, the controllers designed in this dissertation are sensitive to the performance of the user by incorporating feedback on the state of the user. Since the performance of different users can vary greatly, the controllers are designed to be adaptive to the different strength levels and behaviors of a subject. Two examples of incorporating feedback from the user into the controller of an exercise machine are demonstrated in this dissertation. The first machine optimizes the power produced by the user during a workout. Two examples of this type of exercise machine are considered. One is an arm cranking exercise that uses a variable reluctance direct drive motor to provide the resistance for the exercise. The second machine is a recumbant bicycle that usees an eddy current brake to provide resistance. The kinematics and dynamics of the exercise motions for these machines are similar. Using a combination of modeling and experimentation, the inertia, Coriolis, gravity, and friction of the exercise motions are identified and validated. In these control systems, the user's strength is parameterized based on a model of their force output. The model accounts for the position, velocity, and time dependence of the user's force. The velocity dependence of force is assumed to satisfy a linear relationship that decreases with increasing velocity. The strength is then used to define an optimal velocity profile that maximizes the power generated by the user. A velocity controller is designed for these machines based on damping resistance that can track within error bounds the optimal velocity profile, or any other desired velocity profile, such as the common isokinetic exercise. The controller identifies the parameters of the strength model and uses the model to determine the proper amount of feedforward damping. Feedback of the tracking error is used to adjust the impedance of the controller, so that tracking of the desired velocity profile is improved. Using Lyapunov methods, bounded tracking error and passivity of the controller with respect to the user's force ar proven for the controllers described above. Clinical studies are performed toverify the utility of the strength model, the tracking ability of the controller, and optimality of the maximum power regime relative to benchmark isokinetic exercises. The results of the clinical studies indicate the optimal power regime is short erm optimal and long term optimal, despite the larger fatigue rate associated with the high velocity optimal exercise. The force-velocity relationship for the subjects was found to be linear and the power-velocity relationship was found to be parabolic, as the strength model used would predict. The position dependence of the force for both the arm and recumbent bicycle machines was found to agree with the kinematics of the motion. The force-velocity characteristics for each subject was found to be highly variable, validating the need for an adaptive scheme, such as the one proposed in this dissertation, to implement the optimal power workout. The second type of machine designed in this dissertation is a stair stepper with a controller designed to regulate the step rate. This machine essentially performs the dual task of the first machine, by removing the variable behavior of the user from the controlled system, instead of reacting to it. The resistance mechanism in this machine is similar to the eddy current brake used in the recumbant bicycle, except that a permanent magnet is used, and the resistance is adjusted by positioning the magnets with a servo mechanism. Experiments are performed to identify both the servo dynamics and nonlienar step rate dynamics. An adaptive feedforward step rate regulator is designed for this machine that rejects changes in gait and in the effective weight applied to the step pedals, to maintain a constant desired step rate. These type of disturbances are referred to as ``psychological disturbances'' because they are dependent on decisions that the user makes. The multivariable circle criterion is used to prove the local asymptotic stability of the controlled system. Experiments are completed that demonstrate the regulation of the step rate both under nominal circumstances and when disturbances are acting. Considerations for extending the approach used to control the step rate to control of the heart rate are briefly discussed. Since any complete controller design for an exercise machine must incoporate a synthesis of the control with the resistance mechanism, mechatronic issues relating to the calibration and design of the resistance mechanisms for all three exercise machines considered in this dissertation is a recurring subtheme.

In this paper adaptive control of a stair stepper exercise machine is considered. The dynamics of the functional components of the exercise machine are modeled and experimentally identifed. Based on this identified system, a regulator is designed to control the step rate both under nomimal conditions and when disturbances are acting. The disturbances acting on the system result from the unpredictable behavior of the user. Using the multivariable circle criterion, the closed loop error dynamics of the system are proven to be locally asymptotically stable. Experimental results confirm the analysis and demonstrate the nominal and disturbance rejection properties of the controller.

Robotic devices hold much promise for use as rehabilitation aids but their success depends on identifying effective strategies for controlling human--robot interaction forces. We developed a robotic device to test a novel method of controlling interaction forces with the intent of improving force symmetry in the limbs. Users perform lower limb extensions against a computer-controlled resistive load. The control software increases resistance above baseline in proportion to lower limb force asymmetry (balance between left and right limb forces). As a preliminary trial to test the device and controller, we conducted two experiments on neurologically intact subjects. In experiment 1, one group of subjects received symmetry-based resistance while performing lower limb extensions (n = 10). A control group performed the same movements with constant resistance (n = 10). The symmetry-based resistance group improved lower limb symmetry during training (ANOVA, p<0.05), whereas the control subjects did not. In experiment 2, subjects (n = 10) successfully used symmetry-based resistance to alter their lower limb force production towards a target asymmetry (ANOVA, p<0.05). These studies suggest that symmetry-based resistance may hold rehabilitation benefits after orthopedic or neurological injury. Specifically, performing strength training therapy with this controller may allow hemiparetic individuals to focus better on increasing strength and neuromuscular recruitment in their paretic limb while experiencing symmetric limb forces.

A multitude of indoor exercise machines are promoted for improving aerobic fitness and for controlling body weight. Previous investigations have performed physiological comparisons of some of these exercise machines. However, a comprehensive comparison of the aerobic and energy demands relative to level of perceived exertion has not been performed. Such a comparison is important because the intensity of exercise is often determined by the perceived effort. The primary purpose of this study was to compare 6 commonly used, popular indoor aerobic exercise machines to determine which would elicit the greatest rate of energy expenditure at specified levels of perceived exertion.

Experimental results are obtained for a single degree of freedom prototype next generation exercise machine that aims to maximize the user's power output and ensure passivity with the user. In an effort to optimize the user's power expenditure, the desired velocity trajectory is developed that seeks the unknown user-dependent optimal velocity setpoint. A numerical extremum-seeking algorithm is utilized to seek the optimal velocity setpoint while ensuring the trajectory is sufficiently differentiable. To track the reference trajectory and to ensure passivity, a nonlinear controller is utilized.

The goal of this study is to determine the effect of `maintain position' and `relax' tasks on the dynamic of the foot while manipulating a gas pedal. The foot is viewed as a mass-spring-damper system, of which the visco-elasticity can be altered by reflexive feedback and muscle (co-)contraction. The dynamic properties of the foot are described by the mechanical admittance, which determines the foot position as a dynamic function of an external force perturbation. It is hypothesized that humans will change their admittance based on task perception. Experiments were done to estimate the endpoint foot admittance with Frequency Response Functions (FWs). An experimental setup that can simulate a gas pedal with different static and dynamic properties was used to apply continuous force perturbations to the foot. Eight subjects were instructed to either minimize the resulting pedal deviations (`maintain position 3 or do nothing and just rest their foot on the pedal (`relax'). The force perturbation, pedal position, and reaction force were measured, and transformed tot the frequency domain to estimate the closed-loop admittance. All subjects showed a considerable difference between the two tasks, confirming the hypothesis that drivers change the dynamics of their foot to best accomplish a perceived task.

The goal of this study is to determine the effect of amplitude and frequency of force sinusoids on force perception of the foot, in order to design an effective haptic feedback system for gas pedals. Eight subjects were asked to push a gas pedal to a constant workpoint position against a background force of 25 N Force perception was determined for three frequencies and three types of footwear by requiring subjects to respond with `yes' or `no' after each force sinusoid. Psychometric functions were calculated from the data, relating the ratio of yes answers (averaged over all subjects) to the amplitude of the force sinusoid. Although large standard deviations were found for low ratios, a statistically signifcant Just Noticeable Difference (JND) could be determined for the upper boundary of perception. Increasing the frequency of the stimulus decreased the JND. Footwear was shown to have a substantial impact on the JND at all frequencies, the largest effect occurring at the lowest frequency.

This paper presents a set of interaction techniques for hands-free multi-scale navigation through virtual environments. We believe that hands-free navigation, unlike the majority of navigation techniques based on hand motions, has the greatest potential for maximizing the interactivity of virtual environments since navigation modes are of loaded from modal hand gestures to more direct motions of the feet and torso. Not only are the users' hands freed to perform tasks such as modeling, notetaking and object manipulation, but we also believe that foot and torso movements may inherently be more natural for some navigation tasks. The particular interactions that we developed include a leaning technique for moving small and medium distances, a foot-gesture controlled Step WIM that acts as a floor map for moving larger distances, and a viewing technique that enables a user to view a full 360 degrees in only a three-walled semi-immersive environment by subtly amplifying the mapping between their torso rotation and the virtual world. We formatively designed and evaluated our techniques in existing projects related to archaeological reconstructions, free-form modeling, and interior design. In each case, our informal observations have indicated that motions such as walking and leaning are both appropriate for navigation and are effective in cognitively simplifying complex virtual environment interactions since functionality is more evenly distributed across the body.

The development of a device that enables haptic foot interaction for communication over a network is presented. Considering the physical properties of feet we demonstrate that feet are suited for personal, concealed communication over a computer network. First experiments to investigate both the usability and fun of using foot interaction indicate promising results and concrete opportunities for further development.

A new method for researching haptic interaction styles is presented, based on a layered interaction model and a classification of existing devices. The method is illustrated by designing a new foot interaction device. The aim of which is to enhance non-verbal communication over a computer network. A layered protocols interaction model allows to consider all aspects of the haptic communication process: the intention to perform an action, limitations of the human body, and specifications of the communication device and the network. We demonstrate how this model can be used to derive design-guidelines by analyzing and classifying existing communication devices. By designing and evaluating a foot interaction device, we not only demonstrate that feet are suited for personal, concealed communication over a network, but also show the added value of the design-guidelines. Results of user tests provide clues for designing stimuli for foot interaction and indicate applications of foot communication devices.

Unique from other senses, the human haptic system supports two-way communications between humans and interactive systems, enabling bidirectional interaction between users and their surroundings. More specifically, haptic interaction offers an independent sensory channel that the brain can process to further enhance a user's experience in a multimodal environment. Such interaction can speed reaction time and reduce hand--eye coordination errors for computer-related tasks. Many interactive systems use visual and, to a lesser extent, audio cues to present users with information about their surroundings and interactions with objects. Haptic feedback can enhance interactive systems' realism through more natural interaction with objects and the environment. Rupert,1for example, used tactile actuators to provide cues for resolving spatial disorientation in aviation environments when visual cues are absent or misleading. Tan, Lim, and Traylor2designed a haptic car navigation guidance system by leveraging sensory saltation,a spatiotemporal illusion of movement across a person's back. Determining how to best design haptic interfaces is essential for further advancement of such novel haptic devices. An examination of haptic sensory systems and associated cognitive and motor processes should help direct the design of haptic interaction devices. This article surveys the haptics literature and identifies conditions under which haptic interaction displays can enhance human perception and performance. Sidebars present the guiding principles and issues associated with haptic interaction devices as well as haptics design guidelines for multimodal interactive systems.

Haptic feedback has been shown to improve user performance in Graphical User Interface (GUI) targeting tasks in a number of studies. These studies have typically focused on interactions with individual targets, and it is unclear whether the performance increases reported will generalise to the more realistic situation where multiple targets are presented simultaneously. This paper addresses this issue in two ways. Firstly two empirical studies dealing with groups of haptically augmented widgets are presented. These reveal that haptic augmentations of complex widgets can reduce performance, although carefully designed feedback can result in performance improvements. The results of these studies are then used in conjunction with the previous literature to generate general design guidelines for the creation of haptic widgets.

A new method for researching haptic interaction styles is presented, based on a layered interaction model and a classification of existing devices. The method is illustrated by designing a new foot interaction device. The aim of which is to enhance non-verbal communication over a computer network. A layered protocols interaction model allows to consider all aspects of the haptic communication process: the intention to perform an action, limitations of the human body, and specifications of the communication device and the network. We demonstrate how this model can be used to derive design-guidelines by analyzing and classifying existing communication devices. By designing and evaluating a foot interaction device, we not only demonstrate that feet are suited for personal, concealed communication over a network, but also show the added value of the design-guidelines. Results of user tests provide clues for designing stimuli for foot interaction and indicate applications of foot communication devices.

Vibro-tactile displays convey messages by presenting vibration to the user's skin. In recent years, the interest in and application of vibro-tactile displays is growing. Vibratory displays are introduced in mobile devices, desktop applications and even in aircraft [1]. Despite the growing interest, guidelines on the design of vibro-tactile displays are still lacking. Existing guidelines are mainly concerned with passive displays, such as Braille labels on controls, nibs on keyboards and notches on smart cards [2, 3, 4]. In this paper we focus on active displays, either consisting of a single vibrating element (used in for example mobile phones and computer mice) or numerous elements (used in for example active Braille displays and body suits [5, 6]). This paper discusses a first set of guidelines, dealing with the basic vibro-tactile parameters. The set is mainly derived from neurophysiological and psychophysical data. The guidelines indicate the relevant parameters as well as possible pitfalls. As such they can serve as a point of departure for interface designers. Important expansions of the set can come from user evaluation studies and examples of best practices.

In this article we examine earcons, which are audio messages used in the user-computer interface to provide information and feedback to the user about computer entities. (Earcons include messages and functions, as well as states and labels.) We identify some design principles that are common to both visual symbols and auditory messages, and discuss the use of representational and abstract icons and earcons. We give some examples of audio patterns that may be used to design modules for earcons, which then may be assembled into larger groupings called families. The modules are single pitches or rhythmicized sequences of pitches called motives. The families are constructed about related motives that serve to identify a family of related messages. Issues concerned with learning and remembering earcons are discussed.

One important issue for proactive computing is how users control and interact with the systems they will carry and have access to when they are out in the field. One solution is to use multimodal interaction (interaction using different combinations of sensory modalities) to allow people to interact in a range of different ways. This paper discusses gestural interaction as an alternative for input. This is advantageous as it does not require users to look at a display. For output non-speech audio and tactile displays are presented as alternatives to visual displays. The advantages with these types of displays are that they can be unobtrusive and do not require a user's visual attention. The combination of these underutilised senses has much potential to create effective interfaces for proactive systems.

There is a lack of guidelines for designers to use when creating sounds for their interfaces. This paper proposes a set of general guidelines for the creation of earcons based upon six experiments we have performed. Using them a designer will be able to create effective earcons.

This paper describes a novel form of display using tactile output. Tactons, or tactile icons, are structured tactile messages that can be used to communicate message to users non-visually. A range of different parameters can be used to construct Tactons, e.g.: frequency, amplitude, waveform and duration of a tactile pulse, plus body location. Tactons have the potential to improve interaction in a range of different areas, particularly where the visual display is overloaded, limited in size or not available, such as interfaces for blind people or on mobile and wearable devices.

Tactile displays are now becoming available in a form that can be easily used in a user interface. This paper describes a new form of tactile output. Tactons, or tactile icons, are structured, abstract messages that can be used to communicate messages non-visually. A range of different parameters can be used for Tacton construction including: frequency, amplitude and duration of a tactile pulse, plus other parameters such as rhythm and location. Tactons have the potential to improve interaction in a range of different areas, particularly where the visual display is overloaded, limited in size or not available, such as interfaces for blind people or in mobile and wearable devices. This paper describes Tactons, the parameters used to construct them and some possible ways to design them. Examples of where Tactons might prove useful in user interfaces are given.

This paper presents an initial investigation into the use of Tactons, or tactile icons, to present progress information in desktop human-computer interfaces. Progress bars are very common in a wide range of interfaces but have problems. For example, they must compete for screen space and visual attention with other visual tasks such as document editing or web browsing. To address these problems we created a tactile progress indicator, encoding progress information into a series of vibrotactile cues. An experiment comparing the tactile progress indicator to a standard visual one showed a significant improvement in performance and an overall preference for the tactile display. These results suggest that a tactile display is a good way to present such information and this has many potential applications from computer desktops to mobile telephones.

This paper reports two experiments relating to the design of Tactons (or tactile icons). The first experiment investigated perception of vibro-tactile ``roughness'' (created using amplitude modulated sinusoids), and the results indicated that roughness could be used as a parameter for constructing Tactons. The second experiment is the first full evaluation of Tactons, and uses three values of roughness identified in the first experiment, along with three rhythms to create a set of Tactons. The results of this experiment showed that Tactons could be a successful means of communicating information in user interfaces, with an overall recognition rate of 71%, and recognition rates of 93% for rhythm and 80% for roughness.

While the sense of touch is capable of processing complex stimuli, the vibration feedback used in mobile phones is generally very simple. Using more complex vibrotactile messages would enable the communication of more information through phone alerts, however it has been suggested that phone vibration motors are not capable of presenting complex messages. This paper reports a study investigating the use of Tactons (tactile icons), presented using a standard mobile phone vibration motor, to represent mobile phone alerts. The recognition rate of 72% achieved for Tactons encoding two pieces of information is comparable to results achieved in a previous experiment with a high specification transducer, indicating that it is possible to communicate multi-dimensional information in mobile phone alerts. These results will help designers to understand the possibilities offered by standard phone vibration motors for communicating complex information.

Tactile icons (Tactons) are structured vibrotactile messages which can be used for non visual information display. Information is encoded in Tactons by manipulating vibrotactile parameters. This research investigates the possibilities of applying musical techniques to tactile icon design in order to define such parameters. Tactile versions of musical dynamics were created by manipulating the amplitude of vibrations to create increasing, decreasing, and level stimuli and an experiment was carried out to test perception of these stimuli. Identification rates of 92%-100% indicate that these tactile dynamics can be identified and distinguished from each other, and that tactile dynamics could be used in Tacton design.

In this paper, we survey guidance on tactile and haptic interactions provided by various researchers who were not in attendance at GOTHI-05. Its main purpose is to identify potential guidelines that might be incorporated into an international standard on tactile and haptic interaction. This survey also identified a number of controversial areas that will need to be dealt with in developing such a standard. Results are presented in a manner consistent with a companion paper "Initiating Guidance on Tactile and Haptic Interactions", by Fourney and Carter [8].

This work addresses the use of vibrotactile haptic feedback to transmit background information with variable intrusiveness, when recipients are engrossed in a primary visual and/or auditory task. We describe two studies designed to (a) perceptually optimize a set of vibrotactile "icons" and (b) evaluate users' ability to identify them in the presence of varying degrees of workload. Seven icons learned in approximately 3 minutes were each typically identified within 2.5 s and at 95% accuracy in the absence of workload. An extended version of this paper can be found as a technical report at http://www.cs.ubc.ca/labs/spin/.

A new breed of mobile phones has been designed to enable concurrent vibration and audio stimulation, or audio-haptics. This paper aims to share techniques for creating and optimizing audio-haptic effects to enhance the user interface. The authors present audio manipulation techniques specific to the multifunction transducer (MFT) technology. In particular two techniques, the Haptic Inheritance and Synthesis and Matching methods are discussed. These two methods of haptic media generation allow simple creation of vibration content, and also allow for compatibility with non-haptic mobile devices. The authors present preliminary results of an evaluation of 42 participants comparing audio-based haptic user interface (UI) feedback with audio-only feedback. The results show that users were receptive to audio-haptic UI feedback. The results also suggest that audio-haptics seems to enhance the perception of audio quality.

The design of interfaces for automotive information systems is a critical task. In fact, such design must take into account that user is busy in the primary driving task, and any visual distraction determined by telematics systems can cause serious safety problems. To limit such distraction and enhance safety, in this paper we propose a novel multimodal user interface. The key element of the proposal is a new interaction device, named Handy, conceived to exploit the drivers tactile channel to minimize the workload of visual channel. Moreover Handy is suitably integrated with the graphical user interface, which is characterized by a reduced number of choices for each state and has been designed in agreement with the self-revealing approach.

The goal for this research is to study a new class of force feedback applications based on abstract messages we call haptic icons. With the introduction of active haptic displays, a single knob or joystick can be used to control several different, sometimes non-related, functions. The functions associated with these multi-function handles can no longer be identified from one another by position, shape or texture differences. Haptic icons are brief programmed forces applied to a user through a haptic interface conveying an object's or event's state, function or content in a manner similar to visual or auditory icons. This thesis begins with a presentation of several tools that were developed to aid this research. It then describes a series of psychophysical tests designed to obtain the basic perceptual limits for our haptic interface. Knowing these perceptual limits is a prerequisite for proper haptic icon design. We analyzed a set of synthetically constructed haptic icons using Multidimensional Scaling, in order to discover the underlying perceptual processes in identifying different haptic stimuli. Results show that a set of icons constructed by varying the frequency, magnitude and shape of 2-sec, time-invariant waveforms map to two perceptual axes, which differ depending on the signals' frequency range, and suggest that expressive capability is maximized in one frequency subspace. I finish by proposing future work to be done on this area.

We define haptic icons, or ``hapticons'', as brief programmed forces applied to a user through a haptic interface, with the role of communicating a simple idea in manner similar to visual or auditory icons. In this paper we present the design and implementation of an innovative software tool and graphical interface for the creation and editing of hapticons. The tool's features include various methods for creating new icons including direct recording of manual trajectories and creation from a choice of basis waveforms; novel direct-manipulation icon editing mechanisms, integrated playback and convenient storage of icons to file. We discuss some ways in which the tool has aided our research in the area of haptic iconography and present an innovative approach for generating and rendering simple textures on a low degree of freedom haptic device using what we call terrain display.

A haptic phoneme represents the smallest unit of a constructed haptic signal to which a meaning can be assigned. These haptic phonemes can be combined serially or in parallel to form haptic words, or haptic icons, which can hold more elaborate meanings for their users. Here, we use phonemes which consist of brief (<2 seconds) haptic stimuli composed of a simple waveform at a constant frequency and amplitude. Building on previous results showing that a set of 12 such haptic stimuli can be perceptually distinguished, here we test learnability and recall of associations for arbitrarily chosen stimulus-meaning pairs. We found that users could consistently recall an arbitrary association between a haptic stimulus and its assigned arbitrary meaning in a 9-phoneme set, during a 45 minute test period following a reinforced learning stage.

The Guidelines On Tactile and Haptic Interactions Conference (GOTHI-05) is the result of the realization of the need for the International Organization for Standardization (ISO) to standardize guidance on tactile/haptic interactions. This paper reviews existing international standards on tactile/haptic interactions and suggests ways to construct a relevant ISO standard. It proposes potential dimensions and boundaries for a future standard and provides a preliminary collection of draft tactile/haptic interactions guidelines based on available guidance.