Today the team attempted to use a demultiplexer circuit in order to simplify the haptic motor control scheme. While the idea appeared to be able to dramatically reduce the haptic system size, the idea failed in testing.
One current task is to implement haptic motors into the glove so that users can receive tactile feedback. While the motors pictured below are small, 4 motors are needed per hand and each motor comes with a control board. All of these motors, boards, and wiring add up taking away from the projects limited footprint.
Haptic motor unit
Haptic motor control board, without soldered pins
One idea was to feed the motor control board output into a demultiplexer connected to each of the haptic motors. If the demultiplexer output channel is switched quickly, the slow haptic motor response time would allow all the motors to be controlled by one control board. Just imagine the space savings! Unfortunately, the demultiplexer available from MESS only supplies half the current required by the motors. Further, the demultiplexer's output switching means that each motor only effectively receives one quarter the control board output power. While power use posed an issue, only experimentation would fully determine if the idea was practical or not. The team set up a simple proof of concept demultiplexer circuit (see video below) to alternate giving power to multiple outputs. When the demultiplexer output is switched quickly, all the outputs appear to receive power. Unfortunately, the circuit was not able to sufficiently power the haptic motors. While current gain and saturation circuits can be designed it is determined that doing so would take as much space as the demultiplexer would save. As such, the team is deciding to forgo this idea for the sake of simplicity.
Comments