Moving Only the Back Wheels

[AquaMorph]

This year my team is having FIRST wheels in the back and omni wheels in the front. Each wheel has its own gear box and CIM. We are driving the robot with the 4 motor arcade drive. I want to program a special mode where only the back motors move. Is there a way to do this?

[Alan Anderson]

I can think of three ways to do it. One is probably more complicated and hackish than anyone should try. One involves completely ignoring the "Drive" functions and building your own out of regular Motor VIs.

The one that I'd actually try implementing myself is something like this:

Open each drive motor separately. Pass the motors' RefNums into an Open 4 Motor Drive function that's been set to the "existing motor" variant. Pass the rear motors's RefNums into a similar Open 2 Motor Drive function. Now you can choose to invoke the Arcade Drive function of either the 4-motor or the 2-motor Drive set. You'll have to disable the safety on the one you're not actively controlling.


I'm curious -- why do you want to do this?

[AquaMorph]

Originally Posted by Alan Anderson

I can think of three ways to do it. One is probably more complicated and hackish than anyone should try. One involves completely ignoring the "Drive" functions and building your own out of regular Motor VIs.

The one that I'd actually try implementing myself is something like this:

Open each drive motor separately. Pass the motors' RefNums into an Open 4 Motor Drive function that's been set to the "existing motor" variant. Pass the rear motors's RefNums into a similar Open 2 Motor Drive function. Now you can choose to invoke the Arcade Drive function of either the 4-motor or the 2-motor Drive set. You'll have to disable the safety on the one you're not actively controlling.


I'm curious -- why do you want to do this?

Yeah I was think something along the lines of your third idea. We would like to do this to give our robot a better fine turning ability for aiming.

[Ether]

Originally Posted by AquaMorph

We would like to do this to give our robot a better fine turning ability for aiming.

How did that work out for you? Did you actually get better fine turning ability with only 2 wheels powered?

[AquaMorph]

Originally Posted by Ether

How did that work out for you? Did you actually get better fine turning ability with only 2 wheels powered?

I tried the last method and now the robot will not drive at all. I guess the normal four wheel drive will have to do.

[DonRotolo]

Originally Posted by AquaMorph

I tried the last method and now the robot will not drive at all. I guess the normal four wheel drive will have to do.

Giving up that easily?

[AquaMorph]

Originally Posted by DonRotolo

Giving up that easily?

Well I have more important things I have to program.