Add support for main brush, side brush, and vacuum motors

[jacobperron]

Add subscribers to listen for the three different motor commands.

[ghost]

Is this still in the works?

[jacobperron]

@zserlin1 I haven't had time to work on this. There was some work done on this a while ago (#36), perhaps I'll get to it one weekend. In the meantime, PRs always welcome :)

To make the API more clear for developers, I think using a custom message for controlling the motors would be good. A proposal for ca_msgs/MotorSetpoint:

    # For the main and side brush motors, provide a duty cycle in the range [-1, 1]
    # The range of acceptable values for the vacuum motor is [0, 1]
    float32 duty_cycle

[nnarain]

Hi. I was looking into adding a command topic for the vacuum motor. See nnarain@d221878

Currently implemented as a std_msgs/Float32. Would create_msgs/MotorSetPoint be preferable?

[vinnnyr]

I would prefer a create_msgs/MotorSetPoint since std_msgs is in theory deprecated

[nnarain]

Was not aware of that. Thanks!

[jacobperron]

Yes, I am also in favor of a semantically meaning message (e.g. like create_msgs/MotorSetPoint).

[AdronTech]

Would it also be possible to merge this into the foxy branch?

[jacobperron]

Here's a port for Foxy: #97