Motor stuttering when accelerating too fast

True. I never really go full throttle from dead stop, I was just bothered that it happens.

I just did calibration on both motors (with pulleys and wheels on) and got this.

106/906 on front motor 110/909 on back motor

Seems accurate to what I had before right?

Is it buttery smooth when you ease the throttle from a dead stop, no cogging?

Yep! (10 chars),

Small vid: @chaka

1 Like

Thatā€™s how it shoul be. :slight_smile:

1 Like

Thank you both, Im content with how itā€™s currently running. :slight_smile:

1 Like

You can adjust the startup boost between 0.01 to 0.1 in steps of 0.01 - I would suggest starting lower than 0.05 and going up past it to see if you find a sweet spot.

That is the only way to fine tune the start torque based on your weight.

Changing the other motor parameters wont do much.

Also; The shuddering effect will be amplified with a diagonal drive system. Dual drive will have less studdering as the truck wonā€™t be able to see-saw

Also; There is a chance your sensors are not working, I would disable the sensor mode and see what happens.

1 Like

I donā€™t think the startup boost actually does anything (at .01-.05 duty cycle) in my setup given that itā€™s a sensorless value and my hybrid setup runs sensored until 2000erpm. I changed it from .01 to .05 to see if it would help, but it made 0 difference.

I know one of the chances i made helped the stutter a lot (though it still happens), but i havenā€™t tracked down which change it was. I do suspect that it was losing the motor max. Throttling to 60A per motor from dead stop may have caused it to freak out.

Yeahā€¦ to much current in your motor is never really a great ideaā€¦

Maybe Need to turn sensor mode off to get start boost working.

It definitely works though.

You could also try adjusting your phase advance. Setting it to 1.0 gives no phase advance and setting it to 0.0 gives 30 degrees (maximum) phase advance.

oh im sure it does something just probably not on sensored/hybrid :slight_smile: I love my smooth start from dead stop too much to turn sensors off. I love in SF and it really helps with all the hills since itā€™s hard to kick start upwards.

@chaka Could you explain what phase advance does exactly?

Ok I was able to replicate what you are experiencing. If you want to make the vesc foolproof you will need to lower the ramping, max current ramp step (at 1 khz) to .004 This has given me good results.

Remember the multiplier bug still exists so you will need to input .0004 to get the right setting. This will give the motor enough time to rotate and allow the processor to log position before applying heavy loading. You may lose a little snap on the throttle response. Since you are using the canbus and there is a processor lag the slave may still cog so you may want to split your ppm signal wire and run each VESC independent.

The best solution if you want raw performance is to ease the throttle and only go full throttle when you get at least a partial revolution.

1 Like

Thanks chaka! Does the change have to be in a multiple of 10? what if i were to try somewhere in between .04 and .004?

Probably, this seems to be an issue with processor speed. you could also reduce the deadband from 15 to 10 in the ppm menu, be careful if your transmitter strays to far from 50% at dead stick. this should give the processor a little more time.

itā€™s already at .10 :slight_smile: I might just leave the settings as they are and not full throttle too fast too often. Thanks again for all your help.

Thank you! Trouble shooting other riders systems is what gives me more experience and a greater understanding of the VESC.

5 Likes

Hey @chaka,

Did some more testing today and Iā€™ve completely eliminated the issue. I noticed that the same kind of ā€˜coggingā€™ would happen when I broke very hard (just as how I started hard). I have a strong feeling that it has something to do with me running ā€˜current modeā€™ instead of ā€˜current no reverse with brakeā€™. Here are the changes Iā€™ve made since.

Motor Max: 45 (I wasnā€™t happy with my acceleration) Battery Max: 35 (I know youā€™re not a fan of this but I promise Iā€™ll keep an eye on my heat :slight_smile:) Motor Regen (min): 45 Sensorless eRPM: 6000 Max Current Ramp Gain: 0.02 (half of default) PPM mode: Current no reverse with brake Startup Boost: 0.01 Integrator Limit: 120 (re-ran detection a couple times and got 120 average) BEMF Coupling: 850 (got about 860-870 after re-running detection) Turned off traction control Added ferrite ring on sensor wires

A separate issue I noticed was that my slave VESC, front motor, would sometimes fail to respond, or have a delayed response, which meant that I would suddenly get a boost to braking/accelerating a second or two after I throttle the respective direction. I had a feeling this may be due to the long sensor wires sitting right next to the motor phase wires. This is why I added a ferrite ring to the sensor wires closer to the slave VESC.

2 Likes

Hi,

Recently i purchased an Enertion Dual Raptor and iā€™m having the same problem as Jinra in the beginning. When i want to start riding the board from a dead stop or uphill, it stutters until i give more throttle of if i push it a bit up to speed first. It does the same when i give full throttle immediately. The rest is working perfectly. I followed the steps mentioned in the steps above but nothing workedā€¦ Any advice from anyone? Thanks!

Down here you can see my settings.

thatā€™s actually because you have unsensored motors. you have to kick off first then throttle. itā€™s different than the issue i was having

I see. Well i tried to put into sensor mode but then the motors did not do anything anymore. They simply did not respond to the remote, while the vescā€™s were receiving the signal.

The motors are unsensored, they wonā€™t work in sensored mode. You have to hit get sensored motors if you want to start from dead stop