My students and I have been wondering if it is possible to build a drive train that is omnidirectional and can do all the things holonomic drives do, but with only two motors. I was wondering if it could be built using this lineup:

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Is it possible? I can’t test this for another few days. I’m just wondering if my attempts at this are futile or if it is possible.

The short answer is no, that will not work. Look at where the wheels will go when you apply different motor speeds to each side.

The long answer is that the number of control inputs needs to be greater or equal to the number of degrees of freedom that you are controlling.

A standard skid-steer drive has two control inputs (left and right), and two degrees of freedom (translation on the X axis, and rotation around the Z axis). The simplest form holonomic drive, the 3-wheel Kiwi, has three control inputs and three degrees of freedom (translation in X and Y, and rotation in Z). More complex drives have more control inputs, but still usually just 3 degrees of freedom.

It is, however, possible to build a drive train which can translate in both X and Y with only two motors. Doing this will sacrifice rotation in Z. One way is to build a square of omni wheels, with opposing wheels linked to the same motor, which gives you one motor for X and one motor for Y. Depending on your robot, this might be adequate.