How to increase torque saturation threshold on ETH robots

[hu-yue]

Hi,
I would like to increase the threshold of torque saturation of iCubHeidelberg01. Where exactly should this be done?
There is a "TorqueMax" in the configuration xml files under the mechanicals folder, is this the right parameter to change?
Thanks!

[DanielePucci]

@randaz81

[hu-yue]

I tried to increase the TorqueMax and restarted the robot but it seems that nothing changed.

During the balancing on left leg I've seen that on the left leg the hip roll goes in hw fault for torque saturation around 25, and in fact, in the file TorqueMax was on 24. But Even if I increased it to 50 and relaunched everything, it again saturated around the same value.

[traversaro]

I checked the source code (https://github.com/robotology/icub-main/blame/f10921a6889ff19ead17e123672ad6f37892565a/src/libraries/icubmod/embObjMotionControl/embObjMotionControl.cpp#L1383) and apparently (as far I can see) TorqueMax is the right parameter. Perhaps @barbalberto knows something more.

[DanielePucci]

@hu-yue may you try to do the same test with a lower saturation limit?

[barbalberto]

The TorqueMax related to the reading of values, but is not related to the maximum torque the motor can produce.
Can you post the output of the robotinterface to see the exact error message?

[hu-yue]

Ok, I tried with the following limits:

• 50, the saturation warning was again on 24. In this case, the warning appeared several times before the joint went to hw fault.
• 24 (default that was in the file), saturation on 24. In this case, the warning appeared and the joint went immediately on hw fault.
• 20, saturation on 20. As the first case, also in this case the warning appeared several times before hw fault.

The exact warning we get is:

embObjMotionControl::updateMeasure() torque measure saturated to +20.0000 on joint 1, count: 1198

The errors following this are:

from BOARD 6, src LOCAL, adr 0, time 284s 770m 577u: (code 0x0200000c, par16 0x0001 par64 0x0000000100020000) -> MC: generic motor error (see 64 bit mask parameter) + INFO = NO MORE

Unable to set the control mode of board 6 joint 1 in HW_FAULT

The experiment is the one described in my previous comment, the joint that goes on hw fault is left hip roll.

[ale-git]

The reported error is a I2T limit fault, i.e. the motor is absorbing too much current - it is a thermal protection.

[hu-yue]

Is this a new feature? It never happened before

[DanielePucci]

So, they are two different problems:

• the saturation cannot be increased above 24, but it can be decreased. This is being investigated;
• the joint runs into HF because of the - incomprehensible - error @marcoaccame @ale-git

from BOARD 6, src LOCAL, adr 0, time 284s 770m 577u: (code 0x0200000c, par16 0x0001 par64 0x0000000100020000) -> MC: generic motor error (see 64 bit mask parameter) + INFO = NO MORE

As for the first, the warning message is

embObjMotionControl::updateMeasure() torque measure saturated to +20.0000 on joint 1, count: 1198

but the joint 1 may be that of any part, e.g. that of the ankle. @hu-yue, may you increase the limit of all the joints' leg? Also, @barbalberto has just added the info on the part, so if you can update icub-main before testing again it would be great :)

[ale-git]

No, it is a protection that has always been implemented in the motor board... have you ever tried the same task with the other leg? Maybe some hardware problem in the motor has arised.

[DanielePucci]

In light of the above, @hu-yue, can you open other two issues on icub-support, e.g. Weird hardware fault, and Impossibility of increasing torque saturation threshold above 24?

[hu-yue]

I never tried with the other leg. I cannot exclude the possibility of motor problems, lately the robot has been used much more than before.

@DanielePucci I will open another issue for the hw fault.

[barbalberto]

The correct way to change the torque measure saturation threashold is to modify the value
TorqueMax in the config file under
robotname/hardware/mechanicals/part*.xml

[DanielePucci]

Are we sure that the parameter TorqueMax should be under mechanicals? It is not really clear to me why a torque is considered as a mechanical part.

[iron76]

I would say that the maximum torque is related to the overall mechanical structure of the joint group. This includes the motor but also the motor shaft, the bearings and other optional components such as the tendons. If TorqueMax refers only to motors than it should go in the motorSpecs folder.

[francesco-romano]

cc @marcoaccame
What about the EMS number representation?