Bionic Hand v1.1

Custom PCB to mount of the back of the palm of the hand

PCB includes:

- Battery or USB power input & voltage regulation

- Small controller to control movement commands and actuate the motors. I used a tiny pico nano but something like a small ESP32 board could also be suitable

- Several motor drivers (DRV8835DSSR)

- Multiplexer (CD74HC4067SM96) to read potentiometer for each motor. Controller must select which channel to read on the multiplexer using s0-s3. Output is an analog voltage passed to controller ADC

- I2C GPIO extender (SX1509BIULTRT) used to control the enable function of the motor controllers. This is required simply because the controller did not have enough IO, another controller may have more

- The board should have some suitably sized bulk capacitors on the motor inputs. I got a bit stuck here and didn't know what minimum value of capacitance I could use. I wanted to keep the board small and compact (avoiding very large caps). This was one of the final parts to implement.

- I also planned to have another small board on the back side of the thumb with a motor controller for the two motors there. I planned to use flexible (silicone) ribbon cable to link the palm PCB to the thumb PCB. I did not finish the spacing of the connector pads, as well as general finalisation of the PCB spacing and routing

Note: I am predominantly a mechanical engineer, if you find issues feel free to update/fix them and let me know. I can share future PCB versions to add to the project going forward

Thanks!

Mahdi