Profile of the trapezoidal move - position control using FOC

[msingh]

Can someone help me understand the profile of the trapezoidal move? for example if I would like to make a movement of 10 radiance in 10 seconds using the MC_ProgramPositionCommandMotor1 how much of the 10 seconds will be acceleration, constant velocity and deceleration? and can this profile be changed? Ideally i would like to achieve 1/6 accelleration 4/6 constant velocity and 1/6 deceleration, is this even possible? is there somewhere in the code where I can specify this?

[GMA]

Hello,

There is a Position Control Application note:

https://www.st.com/resource/en/application_note/an5464-position-control-of-a-threephase-permanent-magnet-motor-using-xcubemcsdk-or-xcubemcsdkful-stmicroelectronics.pdf

Best regards.

GMA

[msingh]

Dear @GMA​,

Thanks for your reply, I've had a look at this document however I am struggling to find the answer to my question. I have based my question considering the attached graph, if time at D is 10 seconds what would be the time at B and C?

Thanks in advance

Kind Regards

Manpreet Singh

[GMA]

Hello,

Page 7/22:

• total duration DeltaT =  fDuration parameter = 9A then A=fDuration/9 with B=3A
• cruise= l =Deltat/3

Best regards.

GMA

[jartim · Accepted solution]

The code you need to modify is the function TC_MoveCommand in trajectory_ctrl.c. This function currently divides the movement into 9 steps, 3 acceleration, 3 cruise and 3 deceleration. It shouldn't be too difficult to change this to meet your 1-4-1 requirement.

[msingh]

Thanks for your reply this is definitely helpful.

[msingh]

Hi, it looks like it is not as straightforward as we thought, I have made the change as below and I am indeed seeing this change taking effect if I monitor the speed of the motor however the position reached is not as requested by the function. I am using Motor pilot to plot the graphs and below is the result of some tests I have done. Do you think I need to make any additional changes to the code? I have tried to scale the requested position by the error but still no luck to achieve the requested position, I have also tried tuning the PIDs again but didn't help.

[jartim]

Hi, not quite what I was thinking 🙂 I think you should have reduced the number of pHandle->SubStep to an array of 6 (1+4+1) and the SubStepDuration should be the total duration divided by 6 (instead of 9).

[jartim]

Having said that, I've just looked at the trajectory code, and it may be a bit more complicated than that.

You would have to experiment a little there.