Encoders on Drive Motors?

[cdizzle]

Originally Posted by DonRotolo

Get the mechanical guys to fix the problem. Otherwise you will be always reducing power to one side to compensate for the drivetrain problem. With the drive motors disconnected, you will find that one side of the drivetrain requires more effort to move than the other.

I pretty much am the mechanical guy, so what could be the root cause of the problem mechanically? The robot is just a chassis right now, so there isn't much on it except for the motors, wheels and the electronics board.

[Ether]

Originally Posted by cdizzle

I pretty much am the mechanical guy, so what could be the root cause of the problem mechanically?

Chains too tight, gearboxes assembled improperly, bearings binding, wheels misaligned, motor manufacturing tolerances.

Try swapping parts side-to-side until the problem changes sides.

Motors, gearboxes, motor controllers, wheels, you get the idea.

Start with the easiest parts and work your way down the list.

[Greg McKaskle]

Put it on blocks and see if you can determine if any of the wheels rotate less well then others.

Determine if the frame is warped.

With it on blocks, mark the wheels and set the speed controllers to the same value and do a visual encoder to see if it is the drive wheels or speed controllers that are doing it. Is it only at high speeds, or all the time?

To add encoders, there is at least one example that will get you started, and if nothing else, it will help with diagnosis and measurement of the difference between sides. To find the example, you can do it from the Getting Started window/Support, or you can go to the Help menu/Find Examples and look in the FRC/Robot and Motor section.

Greg McKaskle

[Alan Anderson]

A six-wheel drive base will tend to go in whatever direction the frame wants it to when the motors are driven with approximately the same power. I'd definitely look for warping or binding somewhere.

However, I'd also double-check the software to make sure the speed controllers being defined in the code match the ones physically installed. If you're using Talons, you must select Talon from the menu at the bottom of the Open 2 Motor Drive function. If you use (e.g.) Victors while telling the software you're using Jaguars, you'll get asymmetry in motor speeds.

[Greg McKaskle]

It may also be useful to calibrate the speed controllers. New ones shouldn't need this, but older repurposed ones may have different calibrations.

Greg McKaskle

[cdizzle]

Thanks for the help! I'll try debugging it tomorrow.