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ERPM settings restrict carving speed on outer wheel. Poor user experience.

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Paul15578
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ERPM settings restrict carving speed on outer wheel. Poor user experience.

Hey Guys

I am mucking around with setting max ERPM to say the equivalent of 20kmh which works great

But when I carve at 20kmh, the outer wheel that would usually spin faster than the inner remains restricted to 20kmh.

So I believe that usually the wheel is allowed to speed up to cover the greater distance of the carve curve. 

But in this instance the VESC is very good at not allowing it to go over that speed. 

Is there any way to allow one wheel to spin a % faster than the set ERPM limit? Or could this be a good feature to ask Benjamin to implement?

Thanks for your comments

Regards

Paul

 

 

 

 

 

Paul15578
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Or thinking further about it - have a checkbox in vesctool to allow the MAX ERPM setting in reality set the AVERAGE ERPM of the two motors.
 

I will post in feature requests

Roger Wolff
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IIRC there is a setting that allows you to specify whether or not the VESC should actively brake or not to stay below the max ERPM. If you turn that off you should get what you want... 

Paul15578
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Hi Roger

Are you talking about a cruise control setting?

I am talking about ERPM (speed) limiting in normal current control mode. Usually the outer wheel can speed up to whatever speed it likes in a carve which is unrestricted carving. 
But in say 15kmh speed restricted mode, the vescs are constantly stopping the outer wheel that is trying to speed up during a carve from speeding up, so then it feels like it is really restricted to a point where carving is a terrible feeling. 

If the average of the wheels was the ERPM setting this wouldnt be the feeling felt I  believe.

Regards

Paul

Roger Wolff
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I just checked. There is no such setting for RPM that I thought here was. At least it's not here in the june 2017 version of vesc_tool that I have here.

 

PXSS
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That's a feature that was on BLDC tool but is missing from VESC Tool

benjamin
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That setting should be on the PID controller page, and is called allow braking. You can give it a try.

Paul15578
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Hi Benjamin, 
Thanks for the response.

Could you please explain the "Allow braking" option. 
If it is disabled is there no braking available ever when ERPM limiting? 
Or does that mean that the vesc never "automatically" applies brakes to keep the speed from going over?

Currently it feels as though it applies braking when carving, but my friend reckons it rolls faster than its speed limit set down a hill, so it mustnt be applying braking to one wheel (the outer wheel) during a carve. 

Could you please clarify as the help box doesnt. 

Cheers

Paul

 

Paul15578
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Tested the setting with the "Allow braking" on false. I can carve smoothly when rolling down a hill over the set ERPM without restriction, but as soon as the board is controlling the speed, then an unwanted restriction occurs between the two motors when carving. It feels like active braking on one side and then on the other side as I carve. I am not sure what the restriction is or why its there as its not there when under full acceleration and carving "overspeed" down a hill. 

Ackmaniac
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Problem here is that the PID controller isn't involved because the limit is max ERPM and not the PID speed.
Both wheels work independent when it comes to max speed.
To solve the problem they would need the information about the other controllers speed to adjust itself compared to the average speed of all motors.
Sounds doable for 2 motors but will get tricky for more motors like 4wd. And without a PID it could result in a jerky ride when one of the wheels slip because each motors speed influences the power output of all other motors instantly. A max offset might help in that case.
Definitely a interesting topic.