First I tried a small H-Bridge with 2.5 A to supply the DC motors with energy. But this type of motor driver was too small at that point the robot tried to turn on spot the motor driver burned out. Then I bought an upgrade for my Big Rob and now I am able to drive around and to turn on the spot without burning the motor driver. I searched for a motor driver with more than 10 A on each motor out. I found a motor driver with a total of 43 A and it could be controlled by a Raspberry Pi. I decided to buy two BTS7960B motor drivers because they are able to supply a total of 43 A which is more than enough for my four dc gear motors.
The picture below shows the two motor drivers and the Raspberry Pi wired and placed on a cardboard inside my Big Rob.
To make is easy for you to find the motor driver BTS7960B I used for my robot I added an Amazon online shop link.
Connecting the BTS7960B motor driver
You need six female-to-female jumper cables to connect the motor driver with the Raspberry Pi. Two cables are needed to supply the logic of the motor driver with 3.3V (VCC and GND). Two wires are needed to activate each H-Bridge with a high signal generated by the Raspberry Pi to set the spinning direction of the DC motor (R_EN / L_EN). The last two female-to-female jumper cables are needed feed the motor driver with a PWM signal to control the speed of DC motors (RPWM/LPWM).
The picture below shows the wiring of the motor driver.
BTS7960B Python program
I had to re-write my Python program I already developed to control some L298N H-Bridges to control the BTS7960B motor driver. That’s make it very easy for the Python control program to import the new BTS7960B Python program as an module and to control the motor driver without changing anything in the control program.
I uploaded the Python program with some inline documentation which describes which GPIO pins are used. This is important for wiring the motor driver.
The wiring of the BTS7960B was strait forward and with all my experience in building robots very easy. The re-use of my already developed Python programs saved me a lot of time and after a few minutes I was able to driver around with the Big Rob and the new motor drivers. It is very cool to have a strong robot with a lot of torque to drive around.