The mechanical design of the inverted pendulum cart is rather straightforward. The primary mechanical considerations were the propulsion of the cart itself and the behavior of the pendulum.

Propulsion

The propulsion of the cart is provided by a single DC gearhead motor capable of attaining speeds of 150 rpm at 24V. The motor is connected to a drive shaft via pulleys and a timing belt. The pulleys are in a 1:1 gear ratio to keep the output speed high. An idler is included to lessen the slack found in the timing belt as seen in the image below. The drive shaft, as well as the freely rotating shaft, is connected at either end to a pair of 3" rubber wheels.

Cart Drive System

Pendulum

The pendulum consists of a meter stick with two steel disks, attached to the end opposite the cart, to move the center of mass awa from the cart base. The pendulum is attached to the top of the cartvia a bracket and is connected to a potentiometer which sits in the bracket via a set screw. This allows for the motion of the potentiometer to track the motion of the pendulum. Stops are placed on each side of the bracket limit the angle through which the pendulum can rotate. Rotation is limited since without this limited rotation, the pendulum could reach an angle at which it is impossible to recover or at which the cart would flip over due to the momentum of the pendulum.

Mechanical Parts List

Part	Qty.	Source
24V DC Gearhead Motor	1
Pulley	2	McMaster-Carr
Timing Belt	1	McMaster-Carr
Shafts	2	Machine Shop
3" Rubber Wheels	4
Cart Body	1	Machine Shop
Pendulum Bracket	1	Machine Shop
Meter Stick	1
Pendulum Weights	2	Machine Shop