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Drone Rescue — Parallax Forums

Drone Rescue

geo_leemangeo_leeman Posts: 190
in Robotics
Hey guys,

I've had a look around at the various drone rescue (i.e. parachute) systems, such as those from MARS. I'm thinking of a similar design, but with an ESC feedthrough for each motor. In the even the parachute is needed, we would ground the ESC signal wires to stop the rotors to reduce the chance of the parachute getting shredded. I was wondering if there were any thoughts about using a transistor and pull-downs to stop the motors? I haven't had a good play with the ESCs yet, but given what I've read, it seems like that could be a reasonable solution.

For the curious, I'm thinking of deploying a parachute when these conditions are met:
1) System is activated with an AUX channel on the remote (done at takeoff to get a zero pressure for the ground level).
2) Vehicle is above 5-10m so parachute has time to do something.
3) Vehicle is in free fall (accelerometer detection) or rotation about any axis is greater than a threshold TBD.

Comments

  • Kyle M.Kyle M. Posts: 112
    The flight controller hardware is capable of two-way communication with the ESCs (but there's no firmware for that yet on the FC side), and the xRotor ESCs are set up/enabled to actively brake, and can be reversed via software, so there may be some options from that direction as well, though I haven't put much thought into it.
  • geo_leemangeo_leeman Posts: 190
    As a generalized solution do you have any issues with pulling the ESC signal low? I'm thinking this will be a separate unit to be attached to any copter and maybe just a software mod to the ELEV8.... I kind of like the emergency system being totally separate come to think about it.
  • Kyle M.Kyle M. Posts: 112
    geo_leeman wrote: »
    As a generalized solution do you have any issues with pulling the ESC signal low? I'm thinking this will be a separate unit to be attached to any copter and maybe just a software mod to the ELEV8.... I kind of like the emergency system being totally separate come to think about it.

    Sorry just seeing this now. Can you explain a little more about what you mean by this (I know what you mean by pulling the signal low)? Do you mean do we have issues of that happening unintentionally when we don't want it to? Or do we do ever do it intentionally? Or something else?
  • JasonDorieJasonDorie Posts: 1,930
    Servos typically require continuous refreshing of signals, so that's what the FC outputs. Changes would be required to the assembly Servo32HiRes driver to force the motor / ESC lines to stay low. Alternately, if you're going into a shutdown condition anyway, you could just shut down the Servo cog, set the pins as outputs on the main core, and zero their output values. It would accomplish the same thing.
  • geo_leemangeo_leeman Posts: 190
    Hey guys - what I'm thinking is a totally independent unit (that could be used on any quad) - basically either pass the ESC signal from the FC or not and just tie it low in the parachute deployed condition. I'm traveling again this week (and moving to Boulder over the holidays), but hopefully can setup a little demo around the new year and try it out.
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