Robot can't rotate, CIMS stop working !

[cilginbilgin]

We have almost finished our robot and started testing it. When we tried to turn, the robot doesn't move, but when we try to drive straight, it works well. We believe that the CIMs stop working since there is a red light on the power distribution board.

Also the CIM that we used for the ball lifter stops with a clicking sound and stays like that for a couple of seconds and starts working again. There is again a red light on the power distribution board in this case too.

However, when we work with a totally full battery (13.50 volts) the CIMs work a lot better and longer.

There is no mistake with the code so we believe the cause of the problem is low voltage.

What should we do, what might be the reason ?

[Jon Stratis]

What is your drive train setup? If you have a 4-wheel drive with traction wheels, it won't be able to turn very easily (especially if you only have 2 CIMs on your drive train!), and you could be stalling the motors. When they stall, they draw enough current to trip the circuit breakers, which is probably the clicking you hear (they reset, then trip again, then reset, etc).

For your ball lifter, is there any friction in the system? If something is out of alignment, you could be making that CIM motor work a lot harder than you expect, and it too could be tripping the circuit breaker.

Also, check to ensure your frame is electrically isolated - there should be an extremely high resistance between the input terminals and the frame. If not, then you have a short somewhere that could also be causing problems.

[Ether]

Originally Posted by cilginbilgin

We have almost finished our robot and started testing it. When we tried to turn, the robot doesn't move, but when we try to drive straight, it works well. We believe that the CIMs stop working since there is a red light on the power distribution board.

Also the CIM that we used for the ball lifter stops with a clicking sound and stays like that for a couple of seconds and starts working again. There is again a red light on the power distribution board in this case too.

However, when we work with a totally full battery (13.50 volts) the CIMs work a lot better and longer.

There is no mistake with the code so we believe the cause of the problem is low voltage.

What should we do, what might be the reason ?

Tell us about your drivetrain:

Gear ratios (including chain & sprocket gearing)?

skid steer? 4 wheels or 6? drop center? narrow or wide wheelbase? What type or wheels?

[billbo911]

Never mind, already asked above. Man, I type too slow.

The red lights on the PDB right under the wire terminals indicate an open, or missing, fuse/breaker.
In your case, it sounds like you are in an over current situation on the drives when you try to turn.
What drive train configuration are you using. How many motors per side?

As for the shooter, how is it powered and what configuration do you have.

All this may be attributed to binding. Is that a possibility?

[cilginbilgin]

We are using a 4x4 drive with 2 CIMs only. The gear ratio is 2 (the one on the wheel is bigger). The drive train is 27 by 37 inches. Tank drive.

The cables that we use cause a huge tension on the shaft of the CIM.
We checked the frame, there are no shortcuts.

[EricH]

I'd be inclined to say you're tripping breakers. 4WD long robots tend to either bounce like crazy or trip breakers when turning if they have medium/high traction wheels; this one is a breaker-tripper. And breakers tripping have a distinct clicking sound.

Another pair of motors in the drive, properly geared to match the existing CIMs, would help the breaker tripping by splitting the mechanical load between two motors on each side (and electrical load, too). Also, you may need a different ratio in the drivetrain; say more like a 3:1 or 4:1 than a 2:1.

[billbo911]

Originally Posted by cilginbilgin

We are using a 4x4 drive with 2 CIMs only. The gear ratio is 2 (the one on the wheel is bigger). The drive train is 27 by 37 inches. Tank drive.

The cables that we use cause a huge tension on the shaft of the CIM.
We checked the frame, there are no shortcuts.

Sounds like basically a 4 wheel tank drive with 1 CIM per side on a full size frame. Belt tension is excessively high. 2:1 gear ratio.
I think you just identified the problem.

The gear ration is too low. One motor per side in tank drive mode is not enough for that gear ratio. 12:1 might be fine in that configuration.

[MrForbes]

Charge the battery....'

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