make controller brake like steering does

[irapha]

Whenever steering wants to brake, it just sets the pose.brake = True.

When controller wants to brake, it also sets velocity to be negative.

This issue includes:

• [ ] verifying that car_interface is properly braking when pose.brake is set, and velocity is null.
• [ ] making controller's brake interface better, by having a dedicated "brake" button, that sets pose.brake to true. AKA: I don't want to have to reverse in order to brake the car :)

[coletaylor788]

@iRapha The controller node should have a brake button that sets brake = True and sets velocity = 0. I think the reason we were having to use reverse to brake is because we were actually setting velocity. Since there aren't any brakes on the car and we were setting acceleration to 0, it would just coast to a stop. Let me know if I am missing something.

[irapha]

So I agree with you that's how things should be working, but I think that we need to handle setting the velocity in car_interface.

controller and steering should not care about the hardware details. They should be able to just set brake = True and the details about whether we have breaks and are activating those or we don't have brakes and have to set vel=-maxspeed. Handling this should happen in car_interface.

The first part of the above paragraph seems to be the way things work currently, given this.

So this issue is just a matter of making sure that car_interface is translating a "break" message into setting velocity=-maxspeed, which is doesn't seem to currently do.

Then one day when we get brakes ( #79 ) we can make car_interface just activate those.

Furthermore, the readme does not include what button is the break button.

Then we just need to test that braking works in general (from controller, by pressing brake button, and from steering by sending brake=True pose message).