Problems driving straight.

[Ether]

Originally Posted by Daniel_LaFleur

A really tight or loose roller will cause your robot to veer off

That made me think of an experiment for which I'd be quite interested to see the results.

Take a well-crafted mecanum bot that drives fairly straight without the need for any closed loop control.

Tighten all the rollers on the left-side wheels and see what effect that has on forward-only commands on both carpet and hard flooring.

Do you think it would

a) still drive straight

b) veer to the left

c) veer to the right

d) do different things on carpet vs hard flooring

Give a rationale for your answer.

[Daniel_LaFleur]

Originally Posted by Ether

That made me think of an experiment for which I'd be quite interested to see the results.

Take a well-crafted mecanum bot that drives fairly straight without the need for any closed loop control.

Tighten all the rollers on the left-side wheels and see what effect that has on forward-only commands on both carpet and hard flooring.

Do you think it would

a) still drive straight

b) veer to the left

c) veer to the right

d) do different things on carpet vs hard flooring

Give a rationale for your answer.

I'd like to see that experiment as well.

My guess would be a slight turn to the right ("C") as the vector addition on the left side (both straight forward) would be greater than the vector addition on the right side (1 @ 45 degrees right plus 1 at 45 degrees left). I'm just not sure if it would be enough of a difference to cause it to turn.

My post before was for a single mecanum wheel roller set to be tight (or significantly different from the others).

[seg9585]

Originally Posted by Ether

That made me think of an experiment for which I'd be quite interested to see the results.

Take a well-crafted mecanum bot that drives fairly straight without the need for any closed loop control.

Tighten all the rollers on the left-side wheels and see what effect that has on forward-only commands on both carpet and hard flooring.

Do you think it would

a) still drive straight

b) veer to the left

c) veer to the right

d) do different things on carpet vs hard flooring

Give a rationale for your answer.

I'm going to say the robot will veer to the right. Even when driving straight the mecanums should inevitably experience a little bit of slip with rollers. Preventing the rollers from moving will prevent this slip, so you effectively get more forward movement per wheel rotation on the left compared to the right.

I'm envisioning a person walking on an inclined sidewalk which is half covered in snow, and half dry. One foot on the pavement, the other in the snow. The foot in snow will "slip" back a bit with every step, but the foot on pavement gives you the full stride.

[Racer26]

Originally Posted by seg9585

I'm going to say the robot will veer to the right. Even when driving straight the mecanums should inevitably experience a little bit of slip with rollers. Preventing the rollers from moving will prevent this slip, so you effectively get more forward movement per wheel rotation on the left compared to the right.

I'm envisioning a person walking on an inclined sidewalk which is half covered in snow, and half dry. One foot on the pavement, the other in the snow. The foot in snow will "slip" back a bit with every step, but the foot on pavement gives you the full stride.

I'd be inclined to agree. I could also see a possibility for a performance difference between hard floors like tile or concrete and softer ones like carpet. I would think the locked roller side would get even more traction on carpet than on the hard floor and make the effect even more pronounced.

[IronicDeadBird]

Originally Posted by Eloy1073

An Xbox afterglow controller.

I was going to provide you the link to the calibration process but school internet blocks sites that are related to gaming. Just google Xbox Afterglow controller calibration and it should be the first link.