Multi-turn position control

Discussions regarding the Field Oriented Control (FOC) implementation on the VESC.
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raess
Posts: 6
Joined: 02 Apr 2018, 22:32
Location: sweden
Contact:

Multi-turn position control

Postby raess » 08 Oct 2018, 22:28

So we made a a couple of changes in the FW to handle multi-turn position control.
The modified FW is based on 3.33, Which was working quite nice for us.

we do no longer compute shorted angles , we use full revolutions.
The encoder position still remains degrees. For example one can control 0-2160degress for a 6:1 gearbox and the output is 360degress on output.
we added a command in the FW: COMM_SET_POS_CUMULATIVE.
plot2.jpg
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(vesc-tool also need to be updated)


we also updated Pyvesc and Ros driver for this new command.

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video on actuator running ros and position control:
https://www.youtube.com/watch?v=lDOAy9ZJrX0



One problem we are still facing is how one could control the ERPM for the position control. Increasing switching frequency also increases the ERPM for the position control. Which switching frequency is recommend/max for 4.12? running 20kHz gives around 7500ERPM, 40kHz gives around 10500ERPM, 45 gives around 17500ERPM.


If anyone is interested, just give me a shout!

raess
Posts: 6
Joined: 02 Apr 2018, 22:32
Location: sweden
Contact:

Re: Multi-turn position control

Postby raess » 10 Oct 2018, 12:23

So we need some help, for example, how is the ERPM used in the actual foc position controller? and how could the ERPM be changed at motor running time?

raess
Posts: 6
Joined: 02 Apr 2018, 22:32
Location: sweden
Contact:

Re: Multi-turn position control

Postby raess » 14 Oct 2018, 22:16

We are working hard this weekend to implement a cascaded style position, velocity and current control loop in the VESC firmware. Now we can control multi-turn positions with speed settings. Nice!

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nero76
Posts: 1
Joined: 15 Oct 2018, 07:29
Location: Germany
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Re: Multi-turn position control

Postby nero76 » 15 Oct 2018, 07:32

We made a simulator for this new multi-turn cascade position control so everyone can see how this modified VESC firmware works ( ) - Happy controlling :-)

raess
Posts: 6
Joined: 02 Apr 2018, 22:32
Location: sweden
Contact:

Re: Multi-turn position control

Postby raess » 15 Oct 2018, 22:50

Some motion testing with new firmware over ROS.
https://youtu.be/iflbHGTBwwo


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