On Sat, 23 Nov 2019 10:15:53 +0000
Herzog Raoul <[email protected]> wrote:

> dear Nicklas,
> 
> there is no feedback control loop in OpenCN.
> Feedback and Feedforward is only inside the drives.

Agree, OpenCN only need to know the limitations. This could also be the case 
for LinuxCNC depending on configuration though this motion planning is as I 
understand better in OpenCN since it know more about the limitations, motor 
model/equations.

> We use TSD80E drives from the manufacturer Triamec 
> (https://www.triamec.com/de/triamec-servo-drives.html).
> The sampling frequency for the PWM, current control loop and position control 
> loop is 100 kHz !
> The setpoint values coming from EtherCat at a rate of 10 kHz are fine 
> interpolated in the drive and upsampled to 100 kHz.

Could be good to know about.

> One remark regarding our feedrate planning.
> At any time, at least one of the constraints is "active", meaning that either 
> the max jerk is delivered, or the max acceleration, or the max speed.

Or at position. If the corners fit this should be the case, have done this then 
jerk could be changed instantly, CANopen standard 402 have a few other smoother 
curves. No or less feedforward will also add more smoothness especially with 
low gains.

> Sometimes this is called "Bangbang", maybe a misleading term since there are 
> no jumps in acceleration.
> Time optimality automatically leads to this "Bangbang" property.

Bang control I tried, loud bang and inverter broken.


Regards Nicklas Karlsson


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