There are many ways to control a robot arm, with the simplest being a sequential list of rotation commands for the motors. But that method is very inefficient when the robot needs to do anything complex in the real world. A more streamlined technique lets the user move the arm as necessary, which sets a “recording” of the movements that the robot can then repeat. We tend to see that in high-end robots, but Mr Innovative built a robot arm with recording capability using very affordable materials.
This uses an input controller that is roughly the same size and shape as the robot arm, so Mr Innovative can manipulate that controller and the arm will mimic the movements like a puppet. The robot arm will also record those movements so it can repeat them later without any direct oversight. The video shows this in action with a demonstration in which the robot picks up small cylindrical objects and places them at the top of chute, where they slide back down for the process to continue indefinitely.
An Arduino Nano board powers the servo motors through a custom driver board to actuate the robot arm. It takes input from the controller, which has rotary potentiometers in the joints where the robot arm has servo motors. Therefore, the values from the potentiometers match the desired angles of the servo motors. The custom driver board has two buttons: one to activate the gripper and one to record to movements. When Mr Innovative holds down the second button, the Arduino will store all the movement commands so that it can repeat them.
Read more about this on: Arduino Blog