Both use 12V steppers from 5.25 inch drives. The right one uses smaller 5V steppers from a small printer. It is not succesfull because the steppers do not deliver enough pull and I could not find a suitable rear wheel. The essence of a simple Jal program to move the robot is shown below. The delay can be varied to find the minimal step interval which can start the robot.
Similar procedures are available for half stepping and for stepping backward.
25 mS delay between steps end loop A more interesting but still very simple robot follows a line on a piece of paper. I use a black line on white paper. The line is approximately 5 mm wide. The robot is placed on the line before it is started. The main problem is to follow a line which bends abruptly.