Robot Drifting

[Mark McLeod]

Originally Posted by AsimC

Our team is having trouble with our robot drifting to the right while driving straight. We feel that is because one drill motor is running in reverse. I know there is a way to compensate for in in the programming but im not really sure how to do it. Would the Current Sensors help in programming the motors? Any suggestions or examples of code would be very helpful to us. Thanks alot.

There are lots of ways to handle this.

The right/left drivetrains are rarely 100% balanced, so you should always be able to adjust for it in the code as necessary. Be aware that every time you adjust the drive system (replace a wheel, fix the alignment) you need to revisit the code adjustment.

An easy method is to first assume the difference is linear and adjust the more powerful side down to match the less powerful side as a percentage of full power. These will of course be different for driving forwards and backwards, so add an if statement for that.




e.g.,

stronger side power = current power - (current power/full power * constant)


weaker side power = current power

The simplest way to select constant is:


- Run the robot at full power and note which side lags.
- Pick a value for constant above, put it into the code and run the robot again.
- Repeat until you are driving straight.

Remember that constant doesn't have to be restricted to integers like 1,2,3,..
It can be a #define like "#define CONSTANT 150/100" to get a value of 1.5 without using floating point #'s.