Originally Posted by lukevanoort (Post 747925)

In theory, a robot using its mecanum wheels will travel at 71% the speed of one the using normal wheels (assuming both robots are geared the same, and the wheel sizes are the same), because wheel is designed to deliver force at a 45 degree angle to its axis of rotation, and thus some of it is being wasted pointing off in the wrong direction. On the other hand, a mecanum robot can travel forward, sideways and every 2-D vector in between, which provides it the maneuverability to get around obstacles much quicker than skid-steer or Ackerman robots.

In reality, the roller's bearings aren't perfect so a mecanum robot's forward speed tends to be a touch higher than its sideways speed. I don't know the actual difference, and it would be really dependent on loading and the specific wheel's bearings. I suspect if one used decent needle bearings on the rollers, the forward/sideways difference would all but disappear.

Originally Posted by Lil' Lavery (Post 748219)

Actually, Mecanums will travel with the same top speed as a standard wheeled robot, but only apply √2/2 (≈71%) of the force of a standard wheel. The top speed remains exactly the same as a traditional wheel of the same diameter. With reduced force (and thus torque), acceleration and pushing power will decrease though.

Many teams have also been able to balance their forwards and sideways motion through clever programming tricks and closed-loop control systems. It all depends on how well your machine is built, maintained, and programmed.