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Topic-icon Torque Mode - slow response time!

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4 years 4 months ago - 4 years 4 months ago #29530982 by fred.o
Hello,

for my project I am trying to use the closed torque mode for directly controlling the generated force.
Controller is an hbl2360 with 2 bldc motors.

I need to directly set the force (or current), so i chose the closed torque mode and tweaked the parameters to a clean response. But sadly, this response is much slower than the open loop speed mode. Ive attached to images of the measured current. (p=0.1; i=3; d=0, It doesnt get faster with other parameters)

It seems that the current in closed torque mode rises rapidly at first and then goes linear to the desired value. Isnt it possibly to controll the current much faster than that. In open loop speed mode it seems to be working fine.
Any ideas to get a fast current control working?

Open Loop (around 20ms)



Closed Torque Mode (around 50ms)

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4 years 4 months ago #29530983 by TechSupport
There are more specifics required for any closed loop mode. It may be likely there are some other parameters you have not tried adjust.

Speed and acceleration, position velocity.

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4 years 4 months ago #29530985 by fred.o
Thanks, I will try them tommorrow. But are they relevant even if the motors are mechanical blocked to get these current measurements?

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4 years 4 months ago - 4 years 4 months ago #29530986 by TechSupport
The torque mode is trying to get to a current value, and maintain it. The parameters in the PID and your speed and acceleration all work together to do this. Getting to the amps value desired is one thing, but speed is another.

Changing one parameter will have an effect on the other parameters as you continually adjust. Adding more I gain will help, but that is only one aspect. Adjusting your speed and acceleration values will also have an impact.

Increasing your I gain will certainly help out in getting to the desired amps faster as it will cause the change over in command response to work faster(motor power will get to +1000(100% output) faster.

From my testing, adjusting to a higher I gain and adjusting the speed and acceleration parameters had an impact on how fast or slow it got to the desired amp value. The amp value remember is based on the motor amps calculated value and not the battery amps.

See page 28 and 29 of the user manual for more information about the battery amps vs motor amps.

To get a quick change over in command, I set a lower max speed rpm and a high accel and decel value. The max speed/accel or decel + the PID values will be the change of time the controller to get to desired amps and maintain it.

If you use 10 for max speed, and 50,000 for accel and decel, then the change over should be rather close to instantaneous. If you want a slower ramp, then you set a higher max speed and a lower accel and decel.
The following user(s) said Thank You: fred.o

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4 years 4 months ago #29530988 by fred.o
Thank you very much. With your settings I got a response time from around 2-3 ms.

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