Separate power-source for the motors solved the Rpi brownouts.

Background

I have had problems with my RPi rebooting when I run my motors. And I have been told the raspberry pi is very sensitive to power problems. The hypothesis is that the batteries cannot provide enough current to keep all components running. The

Experimental setup

Today I added a second power source directly connected to the H-bridge to test the hypothesis. I hooked up an a 9 Volt battery on the back of the robot. Not the optimal solution since the single battery will probably quickly run out of juice.

9v battery directly connected to the H-bridge

Results

The robot can drive at full speed without any brownouts. The accurracy of the turning is quite bad. The robot turns slightly when it should be driving forward. It also runs in an arc instead of turning on the spot.

Future Work

Next step is to work on improving the predictability of movements for dead reckoning.

Ideally I should give the robot an relative position in meters and the robot moves to that position or very close. For example: Go 0.5 m forward, turn 30 degrees to the right, Go 0.2 m forward.

One of the motors turns a little stiffer than the other. In order to improve the predictability I will first remove the motors and add some oil to the gears. Hopefully both motors will run better. After that I will do a series of tests to try and use PWM to get similar drive on both motors. When that is done another series of experiments to find the error distributions.