The purple boards slotted into the pairs of SIL headers are Pololu Stepper motor drivers. Going this route makes replacing a burnt out chip as easy as plugging in a new module. The terminal block ...

It’s based around the ubiquitous Arduino Uno, paired with a motor control and I/O shield for more connectivity ... off-the-shelf ultrasonic transceiver module, and an NRF24L01 module for ...