We have a 4 motor mecanum drive on our robot, and we are sure that they are attached correctly (the top of the rollers form an X) but when we try to strafe, the front wheels seem to not move and the robot starts to turn. When holding up the robot, the wheels are all turning the right directions at the right speeds. The only time when it works properly is at really low speeds. Our robot is considerably heavy and especially front heavy, but I have tried decreasing the speed of the back wheels as much as to 10% of their usual speed to compensate, but the front wheels are still not moving. Here is my code:
double stick4 = DriveRev * Controller1.Axis4.position();
double stick1 = Controller1.Axis1.position();
(other code)
edrive(stick3,stick4,stick1,10);
// edrive function (this is declared earlier outside of the main usercontrol loop)
// Also we decided to call mecanum drive "edrive" because it sounded nice; it just means mecanum drive
void edrive(double sp3, double sp4, double sp1, double wt = 10){
LF.spin(forward, sp3 + sp4 + sp1, percent);
LB.spin(forward, sp3 - sp4 + sp1, percent);
RF.spin(forward, sp3 - sp4 - sp1, percent);
RB.spin(forward, sp3 + sp4 - sp1, percent);
wait(wt, msec);
}
Does anyone know what the problem could be, and if so, how to fix it?
Do you have them geared beyond a 1:1? because mecanum have a maximum strafe speed and any speed above that just wont work due to not enough torque. it could also just be a not enough torque at all issue, does your robot reach full speed within 3 seconds?
We have a 7:5 gear ratio (the wheels are 7 if thats not the correct notation), and it does reach full speed within 3 seconds. We have been able to get all of the motors to spin and go sideways at full power though, it just requires turning a different amount in relation to the speed as we strafe. We are yet to try the friction and motor watt test, but if anyone knows if the problem is anything else, please tell us. Thank you!
This is just from what I’ve seen, but I dont think you can get Mecanum wheels, just because of how the wheels turn. Anything besides a 1:1 would cause issues I would think.
Heres a link to a previous team thinking about gearing:
Without and accurate knowledge of how much energy the motors are using… you don’t have a way to optimize your changes or tell which changes are needed. Start at the beginning, motor watts & friction.