In this experiment, the car begins to walk, but it is just the simplest movements: going forward and backward and then stopping. This is the first and most important step for car walking. The subsequent experiments are all based on this experiment.
The batteries output 7.2V to the switch module. When you press the button of the switch module, 7.2V will be input to the step-down DC-DC converter module which then outputs 5V after lowering the voltage. 5V is input to the sensor shield to supply for the servo. The MG995 servo at the front is to control the direction the car walks in. In this experiment, the car keeps walking straight forward/backward. The motor driver module is used to drive the two gear motors connected to the rear wheels of the car, which drive the wheels accordingly. Thus, the car begins to walk.
When you press down the button of the switch module, the car starts to go straight. 2 seconds later, it starts to go backwards and then stops after another 2 seconds. If you press down the button for a second time, the car will start to walk again. If you want to change the time the car walks, you can modify the sketch as you like.