Quote:
Originally Posted by gpetilli
Keep in mind that even if the wheels are all spinning at exactly the correct speeds, the force vector they create is a function of the weight on the wheel. If the CG is off or one wheel is lifted off the ground the robot could spin violently.
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I would like to add a clarification to my post above. The amount of torque (and therefor force vector) that a wheel can impart is a function of the traction of the wheel, which is
limited by the weight on that wheel. If the CG is such that the weight is unevenly distributed, one wheel may break traction before the others, changing it's force vector contribution and cause the robot to spin. All this assumes the wheels are spinning at the correct speeds an therefor trying to impart the correct force vector.
As for your wheel velocity correction method, yes it will work (for some time) but will not adapt for changes in the environment or robot. Your range of gains is larger than I have seen in the past, and you might want to look for the root cause. The only time I have had one wheel off that much, we tracked it down to a CIM with a very slightly bent output shaft, which caused the spur gear to over engage the gearbox and load the motor more. Start by looking at your slowest wheel and check your weight distribution. Is the frame planar? With the robot on a flat surface, try sliding a piece of paper under each wheel.