...the robots' controller are 3-platforms: first are 230V connector with power supplies (12V and 24V) and voltage-controlled-lamps, second has STM32 Nucleo (programming in Arduino IDE), 2 relayes (for pump and solenoid valve), distributed-voltage-board, voltage regulator (5V for logic) and four stepper driver TB6560; third platform are 2 fans and emergency-stop button.

Robot can work "as dry", when picking and placing 3D-printed rings by earlies-programming  motions point-to-point; but it can work with mast+Pixy2, which communicating by UART, stepper motions are controlled by AccelStepper library. Robot have limit switches for finding home position after switch-on. With Pixy2, robot can collect scattered disks. Of course, robot have inverse kinematics, but is very simple thanks to linear first axis.

If you want videos about working robot, all it are available in links section :)