Friday, May 23, 2014

Why Mechanum Drives Strafe Slower

In this post, Tao will try to explain why a Mechanum drive strafes slower than an X drive.

For X drive mechanics, see AURA's website.

Since the rollers on each pair of parallel wheels are spinning at the speed of the other pair of parallel wheels, they are spinning at 1/root(2) of the speed of the robot.



In a Mechanum drive, the rollers are angled at 45 degrees from the wheel. When the Mechanum drive is strafing, the rollers spin diagonally so that the robot moves at the same speed as the wheels. That means the rollers spin root(2) or 1.4142 times as fast as the robot is traveling.Therefore, the rollers on the X drive only have to spin (1/1.4142)/1.4142 times as fast as the rollers on a mechanum drive, or 1/2 times as fast. The fact that the rollers on a Mechanum drive spin twice as fast as the rollers on an X drive means that the Mechanum drive has more resistance when strafing, making it strafe slower.

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