Robotology
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Hello, Sorry for bother you again! We have recently started working again with Let's say we want our robot to receive some kinesthetic demonstrations, like in this or this video. We are looking for a complaint behaviour in robot's arms, with gravity compensation, in order for a teacher to move the arms easily. Based on the discussion here and also demoForceImitation, I am setting the following for the first 5 joints in one arm of the robot in my code: It does give the feeling when moving robot's arm same as running the I am not sure about the usage of The modules are running through this part of start up xml application (with no port to connect manual or by the app): Lastly, I could not find what was mentioned here as useful for our propose (the |
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Replies: 3 comments 22 replies
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Hi @paliasgh Regarding the following lines you posted above iimp->setImpedance(j,0.2,0.02);
imod->setControlMode(j, VOCAB_CM_TORQUE); //maybe not needed?
iint->setInteractionMode(j,VOCAB_IM_COMPLIANT);Please, consider the table I provided a long time ago, which states that the interaction mode doesn't go along with the torque control mode. Thus, either you enable the torque control mode or the position control mode; for the latter, you have two interaction modes available: stiff and compliant. If you want to perform kinesthetic teaching, you should enable the torque control mode.
Difficult to judge. It may depend on several factors, including the status of the robot.
You don't have to interact with these two modules. When your code changes the control modes, then they will kick in under the hood.
Correct 👍🏻
It's a quite old piece of SW that grew wildly as a monolithic general-purpose motor component. For the second operation, there are suitable RPC commands that you'll find documented:
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IMG_3239.movHi @pattacini , thank you very much. I now see your point and can understand the table. I see that for Kinesthetic teaching
The video attached here is for after running only imod->setControlMode(0, VOCAB_CM_TORQUE);on joints 0 to 4 in the left arm of the robot. P.S. I just discovered that changing the control mode of any joint in robot's arm to torque control mode, either through
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Hi @pattacini , thank you so much! Searching for ports with I also tested if some relevant ports actually publish any output: (The first one gave no output, the other two were publishing data.) |
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Thanks for the test @paliasgh 👍🏻
You may also consider attaching here a file containing the output of |
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Hi @pattacini , thanks for looking into the issue!
Here is the |
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There is also something unusual regarding IMG_3274.movIn fact, the main joints stay in idle mode (I can switch them back to position control though) and some others give fault as you can see in the screenshot below.
This means, every time we want to restart |
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Hi @paliasgh I deem that we would need at this point to open a proper support ticket at https://github.com/robotology/icub-tech-support/issues detailing the problems clearly. Would you mind doing it? Copying and pasting should be sufficient. In this regard, I realized that browsing Sorry for bothering you with yet another log session! |
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Hello again @pattacini, Now that the issue discussed here is resolved, I wanted to bother again regrading this topic. Thanks in advance for you help! When
However, moving any of the robot's arm still is not easy. I mean, it is super hard to move the arm of the robot as seen in the video you mentioned because some of the joints (mostly Joint 0) feel very heavy. In fact, setting the joints in Idle mode makes them easier to move compared to Torque control mode! I can feel something is happening there (maybe due to IMG_4635.MOVJust to remind you, what we are looking for is to simply let the robot go through some actions (receive kinesthetic demonstrations) pretty much like the video mentioned above. |
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Hi @paliasgh, hope to find you well. We would like to inform you that in the past days we worked on this activity and, in particular, we fixed the head IMU reference frame in the urdf. I attach here some references:
This fix affects all the iCubs >= V2_5, so also your iCubWaterloo01. In order to use the proper urdf, you can Please, let us know if now it works correctly. Martina |
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Hello @martinaxgloria, Thanks a lot! It seems to be working. I could replicate what you demonstrated in your video. However, there are still some issues. gravityCompensation seems to be working well only for Joint 1 (and maybe 2). In the video below, I first test moving mostly Joint 1 and 2. The robot holds its arm okay and moving its arm is easy. When I try to move the arm like in the next video, I can not. The arm is in fact very stiff in that direction (Joint 0: shoulder pitch). Can you test something like that in our robot? Testing video: 1.2.movImpossible movement: 2.mov |
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Hi @paliasgh, this is a very odd behavior. Moreover, we found an issue with the frame of the FT sensors mounted on the arms of the robot, so we are currently working on that. This could be related to your issue. We will keep you updated! Martina |
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Hello @martinaxgloria , I hope you are doing great! Is there, by any chance, any update on this? Thanks! |
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Hi @paliasgh, sorry for the late reply. As said in the last comment, we found a bug in the frames of the FT sensors of the arms: in particular, all the iCub with version >=2.5 (so, also yours), have the reference frames wrongly defined inside the simulation model, so the error is basically in the urdf. We found a workaround to properly visualize the right measurements on RVIZ, but unfortunately We are going to understand how and when to plan this activity. We will update you as soon as we have some news. Thank you, |
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Hi @paliasgh
Regarding the following lines you posted above
Please, consider the table I provided a long time ago, which states that the interaction mode doesn't go along with the torque control mode. Thus, either you enable the torque control mode or the position control mode; for the latter, you have two interaction modes available: stiff and compliant.
If you want to perform kinesthetic teaching, you should enable the torque control mode.