4 Motor Tank Drive Problem

[nickcvet89]

So yesterday we encountered a problem with our tank drive program. Last year we used only 2 motors for driving last year, this year we are using 4 motors instead. In the default code i replaced the arcade drive with tank drive and added the close vi in finish. Everything worked fine on our past year robot with 2 motors but when i replaced the open 2 motor vi with an open 4 motor vi we had some issues. The robot drives with the open 4 motor but only 2 of the motors work, one from each side. We have a victor for each motor but only 2 of the victors are receiving signal. The robot is driving but only 2 of the motors are active we would like to get all of the motors working. If anyone has any ideas on how to fix this issue please post. Thanks

[Alan Anderson]

I will suggest two things. First, make absolutely certain that the PWM channels you're specifying in the Open 4 Motor are the ones connected to your speed controllers. Second, try reseating the PWM connectors in the Victors; they are notoriously difficult to get right without lots of practice.

[dotbran]

Why would you need four motors for tank drive?

[pSYeNCe]

Originally Posted by dotbran

Why would you need four motors for tank drive?

Just for more power, I would imagine.

As for the actual problem, I agree that you should double check the PWMs in the program and check the physical connectors. We are using Jaguars for the same purpose without issue.

If your PWMs in the program are correct, I would think it's a hardware problem.

[dotbran]

Originally Posted by pSYeNCe

Just for more power, I would imagine.

That makes sense.

In that case, how about just doing two instances of tank drive (one for front, one for back) and setting everything to control both in parallel?

Or, are you sharing each pair of motors with each pair (L/R) of wheels?

[pSYeNCe]

Originally Posted by dotbran

In that case, how about just doing two instances of tank drive (one for front, one for back) and setting everything to control both in parallel?

Hmm, I don't see any reason why not. I'd say try that, and if that doesn't work and you're sure of the PWMs then you definitely have a hardware problem.

[Alan Anderson]

Originally Posted by dotbran

In that case, how about just doing two instances of tank drive (one for front, one for back) and setting everything to control both in parallel?

If the Open 4 Motor isn't working, two Open 2 Motors with the same four PWMs wouldn't open either.

Or, are you sharing each pair of motors with each pair (L/R) of wheels?

That is the typical way to do it, with two motors on each gearbox.

[Josh987]

Make sure you open the 4 motors in "begin" and that it is referenced properly in "teleop", "partial tasks", and "end" vi's. Also when running the code check on the drivers station to see if the PWM's are being sent a signal.