Mechanical System:
The majority of the mechanical design in this
project was concerned with attaching the stepper motor to the shaft that
controls tilt and the brush motor to the strings that control the telescoping
motion.
The stepper motor was be attached directly
to the rotating shaft that opens and closes the blinds. Two ideas
for connection were considered: a belt and a rigid connection. Connection
by a belt would be the easiest to build, but there are concerns about slipping,
especially with a device as precise as a stepper motor that moves in small
increments. Therefore, it was decided that a rigid connection would
have to be manufactured.
The brush motors were also housed above the
blinds and were rigidly connected to a shaft. This shaft was connected
to the strings that control the telescoping of the blinds. When the
motor turns in one direction, the strings will wrap around the shaft, pulling
the blinds up.
When the shaft moves in the other direction,
the strings are released, allowing the blinds to fall to the desired height.
The brush motor was selected because of its resistance to an external force.
Thus the weight of the blinds on the motor did not cause the shaft to rotate
and the blinds stayed at the desired height.