This is our second year attempting to use mecanum wheels on our robot for sideways motion, we feel like this will increase our speed and ability to pick up balls. However when I download and compiled the sample program “mecanum wheel-basic” and plugged the drive motors into the ports the robot moves forward and backward but when attempting to go sideways it slightly moves sideways but starts to rotate. This rotation is not the same as the rotation as what’s supposed to happen using the right joystick. Could anyone share a similar experience or have suggestions on how to fix this issue?
Mecanums require that every motor be correctly programmed and wired. It is possible to have all motors move forward and strafing be messed up. Attached below is a diagram of the mecanum wheels and how each motor must spin in order to achieve sideways motion. Ensure that your wires are not reversed, and if you are using a 2 wire motor port, make sure it is inserted correctly. This can be frustrating if it doesn’t work, but if you follow the diagram and diagnose the issues you’re having you will be able to make it work.
You should also make sure that your wheels are all facing the correct directions (as in the above picture).
I’ve almost always seen the rollers on a mecanum drive form an X formation like in the picture I’ve attached. My team had an issue where our robot would move forward and sideways properly but would not turn properly which was fixed after we configured the wheels to match the picture.
Also, keep in mind that in a set of four mecanum wheels, there are actually two different types of wheels, and these need to actually be swapped in order to actually change the configuration.[attachment:56c7dd744ccd6][attachment:56c7dd744ccd6][attachment:56c7dd744ccd6][attachment:56c7dd744ccd6]
Another consideration with Mecanum wheels (once they are all mounted properly) is that for optimum control, the center of mass of the robot needs to be very close to the geometric center of the wheelbase. I haven’t personally tried them on a VEX robot, but on an FRC robot at 120 pounds, this has a huge impact on control while driving.
I had this only robot last year. Just give up on them. If I were you, I would use smooth 4" at front and Omani at back. The Omani wheels allow you to turn better while still keeping in the same place.
what’s so bad about mecanums?
They are very slow at what they do, that’s why for this year, a lot of teams who want to strafe are going for X-Drives