I didn’t explain the diagram, should have done that.
and this only applies when not using the inertial sensor for turns.
The calculation to determine how to turn the robot a given number of degrees uses three parameters (well, and gearing but I’m ignoring that here)
wheel circumference (c)
trackwidth, the distance between the wheels, (t)
wheelbase (b)
The wheelbase is where the difficulty comes in, it may be the distance between the wheel axles, but for a robot that, for example, only drives the front wheels it will be much less.
Usually it will be twice the distance from the robot’s center of rotation to the driven axle, that’s what the blue box in the diagram of the V5 clawbot I posted is trying to illustrate, wheelbase in this case would be set to 40mm.
Here is a drawing of the old cortex era clawbot, it was driving all four wheels and the center of rotation was more or less between the axles.
