loop error deadband SBL1360; I want to used closed loop control with analogue feedback to find position, then stop and apply brake

6 years 3 months ago #29529475 by kitepowersolutions
I have a SBL 1360 connected to a maxon motor with integrated power off brake which in turn is connected to a mechanical load with position feedback coming from a potentiometer. I wish to release brake, move to a new position and then re engage brake so that I can hold the mechanical load on the brake.

The problem I have is that although the system can effectively track the postion from my input commands, when the location is reached it never quite gets over the finnish line (probably due to the nature of the feedback) and there is always a tiny bit of correction going on; subsequently the motor remains turned on and the brake can never apply.

What I believe I need to do is set a deadband in the 'loop error' to eliminate these small corrections. Unfortunately I can find no option for doing this in ROBORUN+.

Any Ideas what I might do? (other than using a external controller for position and running in open loop speed mode)

Please Log in or Create an account to join the conversation.

6 years 3 months ago #29529476 by roboteq
There is no such configuration setting available.

You will need to write a small script that will switch the controller to open loop whenever the conditions you set are met. For example, a given error threshold for a given amount of time.

Please Log in or Create an account to join the conversation.

6 years 3 months ago #29529521 by dimracer
I have a raser like question. SBL1360 produce oscillations at the null setpoint when it is in closed loop speed mode and hallsensor being the feedback sensor. The same effect can be observed in case of closed loop position mode. I think the reason of this oscillations is discrete kind of the hallsensor. Usually as I know this type of oscillations are removed be means of deadband. How can we suppres this oscillations in this case?

Please Log in or Create an account to join the conversation.

6 years 3 months ago #29529532 by Griffin Baker
In the closed loop position mode, you can adjust the integrator limit %, so that as the errors accumulated become large over time, the integrator will limit the % of the output. This will help reduce the oscillations.

In the speed mode, you do not want to change this value, since it relies on this value. In speed mode, make sure to adjust the I gain over the P gain. Start with a low I gain first and then increase until the speed is almost reached without oscillations. Then add a little bit if D gain to provide an extra boost to get to desired speed. Not required, but it may be needed.

Then add in small amounts of P gain so that the speed desired is achieved.

Please Log in or Create an account to join the conversation.

6 years 3 months ago - 6 years 3 months ago #29529547 by dimracer
I tried to change P, I and D gains. But oscillations are observed even at the smallest P and I gains. I suppose the speed calculating algoritm to be the reason. Every tick of the hall sensor counter while changing direction shows the permanently big calculated speed change. It produce in turn big loop error jog wich couse a big setpoint change. The second reason, I think, is permanently big speed jog at the start up, because the power invertor in trapecoidal control can't smoothly change speed as opposite to sinusodal PWM. So, I think, the only method to remove this type of oscillations is feedback deadband insertion. Are there any ways to do it in sbl1360?

Please Log in or Create an account to join the conversation.

Moderators: tonysantoni
Time to create page: 0.107 seconds