TMCM-163 - permanent brake

[fritz194]

For our application - we need to brake the motor in stopped mode.
This should be quite easy with a generic BDLC controller.
Somehow it looks like such feature is not implemented in the actual firmware.
Is there a trick using normal parameter to accomplish that ?
ROL or ROR with speed 0 or similar ?
On playing around with the TMCM160 software - I have seen situations with active coil current
and motor stalled.
Suggestions ?

[M.Jankowiak (TRINAMIC)]

Use the parameter 149 "Hard stop flag" : Set (1) to break motor hard, if velocity
is below or equal active break velocity (see parameter 7).

[fritz194]

Thanks,

I tried the hard stop flag in earlier tests and it didn´t work as expected - was some other issue probably
no _IT WORKS_

[fritz194]

With the hard stop flag set - I got "passive" brake - means motor coils shortened,
As I can see with the TMCM-160 tool - the controller knows the position in stopped mode with flag set.
So if I turn the motor against the "passive" brake, the controller "sees" how the target position changes due
to the hall sensors.
So it should be possible to implement an passive/active break which tries to keep the stop position.
(is there a wishlist ?)

[TRINAMIC_BD]

For now, you can use the positioning feature to always position the motor back to the desired position. However, it becomes switched off, once the target is reached, unless you set MVP_target_reached_distance to zero. The feature of position stabiliztation works very nicely with an encoder module, like TMCM-170.

[fritz194]

If you can control/limit the phase currents of the motor - it should be possible to apply a stop current which increases the stopped torque momentum.
This should be enough to handle a constant load.
With a varying momentum in stop condition - an encoder might be useful.
So we have to do our own thing to support that...
From hardware point of view - the 163´ module should be able to do that.

rgds.

[fritz194]

Finally, I found a perfect solution by modifying the current limit parameter depending on actual position.
I send a position command - which can´t be completed due to limited motor current.
Same with acceleration ramps or whatever - just modify current limit depending on actual position.
As long as you have a constant load this will work out.
In our setup the motor speed is controlled by the load and the current limit - target speed is some hypothetical value only.
To overcome minor but potential step-loss in the absence of an encoder - I recalibrate the position at a determined position with a proximity switch we need anyway.

[TRINAMIC_BD]

Thanks for posting your solution!