[DiffDriveController] Add velocity limits for individual wheels

[arslogavitabrevis]

Pull request for feature request #470

[bmagyar]

Could you please add some testing too?

[arslogavitabrevis]

I just had a look at the test that are already there.

I think I should bring the code added to the update function and the code that I will have add to the on_configure function for the test to be working well in a subclass like if was done for the speed_limiter to keep it clean. Do you think I should create a new class wheel_speed_limiter or should I enhance the actual speed_limiter class with the wheel limit feature?

[destogl]

Can we somehow use the pre-defined structure for joint limits to declare and read the parameters? (see JointLimitsParam class

Can this limiter be useful for other controllers?

A year ago we were working on a "SimpleJointLimiter" that would be in the same package as above limiter and reusable across controllers and other packages.

[mergify]

This pull request is in conflict. Could you fix it @arslogavitabrevis?

[arslogavitabrevis]

Yes I think it would be interesting to use the JointLimitsParam. I will try use it.

Do you think I could pause this pull request in the meantime?

[mergify]

This pull request is in conflict. Could you fix it @arslogavitabrevis?

[christophfroehlich]

As we have now the possibility to parse the URDF directly, it make sense to use the velocity limits directly from the wheel joints. see #949 for an example.