VESC for VR treadmill

Support for creating custom user applications on the VESC.
pathbender
Posts: 3
Joined: 23 Dec 2017, 20:26
Location: Hannover

VESC for VR treadmill

Postby pathbender » 23 Dec 2017, 20:32

We want to controll two VESC via external CAN bus to run two brushless 6374 motors on our VR treadmill with independent speeds each. (For better understanding, the first motor is driving the treadmill belt, the second motor is rotating the ball grid array on top of the belt.)
Now, the question about this is: Is it possible to use the PID speed controll via external CAN bus for both motors?
In other words: Is CAN bus controll offering the same possibilities like (for example) PPM controll in which the PID speed controll is possible?
Any help is highly appreciated!
Sincerely
Frank
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rew
Posts: 943
Joined: 25 Mar 2016, 12:29
Location: Delft, Netherlands.

Re: VESC for VR treadmill

Postby rew » 23 Dec 2017, 23:48

You do NOT want to tell both motors to do the same speed. Any minor error will cause the motors to fight each other.

With PWM control, you get a slightly better situation. The effective resistance of the motors will allow them to adjust a bit to small errors. Still it is quite possible that one motor will be powering everything AND the other motor.

You can set the speed on one VESC and then read off the current it is providing to the motor. Then command the other motor to do the same. Maybe the setting: "Slave to other VESC" already does this.

pathbender
Posts: 3
Joined: 23 Dec 2017, 20:26
Location: Hannover

Re: VESC for VR treadmill

Postby pathbender » 24 Dec 2017, 12:18

...maybe the question was not clear enough. Another try: For example: The belt drive (not visible in the picture) may go full forward while the ball grid array drive is running slow speed in reverse direction. There is no mechanical connection between the motors, the motors do not "fight each other".

Both motors have to run completely independend speeds and directions but they need to keep the actual speed exactly at set point, no matter which load (=torque) is present. This is why we need PID speed controll. The speed set points are send via CAN bus seperately to each VESC and each VESC got its own CAN ID number.

"Slave to other VESC" is for sure not what we need.

Again the Question: Is it possible to have PID speed controll using CAN bus communication and send each motor his own independent speed. How to configure the VESCs for this purpose?

Sincerely
Frank

pf26
Posts: 309
Joined: 28 Mar 2016, 14:37
Location: FR Valence

Re: VESC for VR treadmill

Postby pf26 » 28 Dec 2017, 17:53

Yes it is (possible).
You need to firstly connect each VESC to the VESC tool and set a unique CAN ID for each VESC.
Now you connect both VESCs on the same CAN bus and send specific commands to each VESC using its CAN ID parameter.

pathbender
Posts: 3
Joined: 23 Dec 2017, 20:26
Location: Hannover

Re: VESC for VR treadmill

Postby pathbender » 28 Dec 2017, 18:00

pf26 wrote:Yes it is (possible).
You need to firstly connect each VESC to the VESC tool and set a unique CAN ID for each VESC.
Now you connect both VESCs on the same CAN bus and send specific commands to each VESC using its CAN ID parameter.


Dear pf26
...and just by doing this the PID speed controll is enabled automatically?? There is no need to chosse particular settings in the app tab (for example)?
Sincerely
Frank


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