April 24, 2016

Jumping Leg

After 2 days of debugging (and only partially fixing) a mysterious SPI communication bug that appeared out of nowhere, here's a jumping leg:

A few things to note:
  - This is with current limited to 40 amps on the motor side.  For more current, I'll need to a smaller phase current shunt.  The current limit definitely gets saturated here.  The boards and motor can't handle that current continuously without real cooling, but seems to handle it just fine in bursts.
 - The linear bench supply powering things got pretty sad here.  You can hear/see it click into constant current mode, which certainly doesn't help jumping performance, and see the voltage spike as the leg lands and motors regen.  Needs more battery.
- This is at 12V, not the maximum 24-ish the controller's can handle.  Also, at peak motor power, the supply sags to ~8V, which may significantly affect jumping performance.

GIF infinite loop mode:


  1. Hi,Ben Katz

    I'm doing the same job as you. It's nice to see the work you're sharing.
    My robot called XDog: Small and Low-cost Four Legged Robot

    XDog need improved, but next month I'm going to go to work, four-legged robot can only play in the amateur.

    Look forward to your future work.

    Wang Xingxing China