Arm Twister2

Arm Twister with two belts

After exploring arm twisters with a single timing belt, we thought it would be better to look into the two belt option. An arm twister with two belts would apply more skin stretch and this would be easier to sense while in motion. The challenge is to make a device that it small enough to be worn by a person in motion.

Current Prototype:

The biggest challenge in this design is to find a small motor that is powerful enough to apply the desired skin stretch. After doing much research (see ExploringMotors) we found a motor that satisfied the basic specifications ( <12mm diameter, 15-70 gear ratio, encoder packaged, stall torque greater than 20mNm). Once the motor was found, a CAD model was made based on the motor dimensions. One pulley is attached to the motor and the other pulley is attached to the shaft. The timing belts that go over the pulleys twist the arm in opposite direction. The list of parts ordered for this prototype is listed in PartsList.

Solid Works CAD model:

• 3D View
  

• Side View
  

• Top View