FarmDogg Rover Pixhawk to actuated braking

Posted by Melissa Brandao on July 19, 2015 at 9:43am

hi all, 

so we're getting close with getting the pixhawk installed in the FarmDogg (this week) and we're working through some of the issues related to braking and steering. Braking in particular, we've entirely replaced the mechanical brakes with actuated brakes but integration with the pixhawk we're not entirely sure how that's going to work. Does anyone have any insight into pixhawk to rover braking integration? 

Melissa

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Replies

  • MikeRover July 23, 2015 at 5:06am

    The braking built into Rover is meant for ESC-controlled vehicles and relies on the ESC itself to provide braking.

     

    One option is to set the limits of your motor controller such that "negative" values are ignored, and run a second big servo off the same channel pulling on the brake via a cable. When the throttle is high, the servo will let the cable go slack, and the motor controller will provide power. When the throttle is low (braking) the brake cable gets pulled and the motor cuts out.

     

    If your brakes are controlled by some sort of PWM trigger, then it's even simpler - configure that to do nothing until the PWM signal goes "negative".

     

    Regardless, you only have one channel that drives both accelerator and brake.

  • Developer
    Grant Morphett July 22, 2015 at 5:41pm

    Currently braking is controlled through the Electronic Speed Controller (ESC) if it supports braking.  If you search for braking on the parameters page:

    http://rover.ardupilot.com/wiki/apmrover2-parameters/

    You will see we have 2 parameters that apply to braking when cornering or if going faster then desired.  Apart from that there isn't any automatic breaking control.

    I'm going to guess you want to control the braking via a PWM channel to the actuator controller?  We don't support this currently but its code so anything can be done.  The question is what scenario's should we apply the brakes in?  Just the ones described above?  Or are there others?

    Thanks, Grant.

    Thanks, Grant.

    • Melissa Brandao > Grant Morphett July 24, 2015 at 8:21am

      Thank you Mike and Grant,

      We're in the midst of getting the actuators on the brakes installed today so over the weekend we should be able to have determined (wish us luck!--big day next Wed!) I'll let you know what we came up with. Since we want both rider and riderless mode we're thinking that we'll just let the regen be the brakes for riderless mode.

      Best

      Melissa

  • Matthew Reimer July 19, 2015 at 12:07pm

    I've hooked up pixhawk a couple of different ways to control my tractor, some methods have worked better than others. If you give me some more details I can make a suggestion.  What do you mean by actuated brakes? What sort of braking system is it, how does the operator interface with it now?  Any kind of pictures you can provide will likely be helpful.

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