VESC for robotics

Support for creating custom user applications on the VESC.
dpetrillo
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Joined: 24 Dec 2015, 01:47
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Re: VESC for robotics

Postby dpetrillo » 25 Jan 2016, 21:49


erwincoumans
Posts: 25
Joined: 16 Dec 2015, 02:16
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Re: VESC for robotics

Postby erwincoumans » 31 Jan 2016, 16:39


itman496
Posts: 15
Joined: 28 Jan 2016, 09:41
Location: NJ, USA
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Re: VESC for robotics

Postby itman496 » 31 Jan 2016, 22:27

How does it work for you? How much torque do you get? How hot does everything get when holding itself still? Any issues with power supply?

To control using step/dir control maybe I can adapt grbl or something to use uart instead of step/dir.. unsure.

madcowswe
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Joined: 08 Jan 2016, 15:37
Location: San Jose
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Re: VESC for robotics

Postby madcowswe » 18 Apr 2016, 22:43


pf26
Posts: 310
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Location: FR Valence
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Re: VESC for robotics

Postby pf26 » 20 Apr 2016, 10:35

I am also using a Vesc for automation, where accurate and fast dynamic position control is required. Positions are sent over CAN bus at 200 Hz from another board. It works : .
But it is difficult to tune the position PID. I have to use a large Integrator value, and this causes large errors (+/-25 electrical degres) upon speed reversal. Increasing proportional gain makes it more jerky.
My understanding with the current VESC implementation, I have :
- position PID loop at 10kHz (not 100% sure)
- encoder (AMT103) with 8192 counts, giving only a few counts per kHz at low speed
- set_position routine at 200Hz (I could increase this, but not much because the CAN bus is heavily used for many sensors also)
With very low inertia and powerful motor, the PID loop can reach the set position very fast. But then it will stop until next position request arrive. This makes the movement jerky and currents spikes in both directions.
I think precise and fast servo control require at least to set both position and speed to next position. Then we could do some trajectory plannig as described here for instance :

I will try to implement this on Vesc.


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