Finger control modes change for all the fingers at the same time

[PasMarra]

torque_mode_finger.mp4

Changing control mode for a finger causes the same change also for the other fingers.

[traversaro]

Back when me and @Nicogene designed the coupling support in Gazebo, that was indeed the intended behavior, see

gz-sim-yarp-plugins/plugins/controlboard/src/ControlBoardData.cpp

Lines 89 to 102 in 1372014

	// If there is coupling let's check if we have to change the interaction mode for all the coupled joints
	if (this->ijointcoupling)
	{
	// If the joint is coupled, we have to change the interaction mode for all the coupled joints
	if(std::find(coupledActuatedAxes.begin(), coupledActuatedAxes.end(), j) != coupledActuatedAxes.end())
	{
	for (auto& actuatedAxis : coupledActuatedAxes)
	{
	this->actuatedAxes.at(actuatedAxis).commonJointProperties.controlMode = desired_mode;
	}
	for (auto& physicalJoint : coupledPhysicalJoints)
	{
	this->physicalJoints.at(physicalJoint).commonJointProperties.controlMode = desired_mode;
	}

. This was done for starting with a simple implementation, but we can always change it if it make sense to have some different behavior. Just to understand, which behavior do you would expect instead? Is there any physical robot that uses YARP interface that is actually implementing the behavior that you expect?

Taking a step back, please note that at the moment the torque control mode is not supported for coupled joints, see #247 for more details. Can you explain what you would like to achieve in controlling in torque control the hands? As far as I know, torque control mode is not supported in any hand of iCub or ergoCub robots.

[PasMarra]

which behavior do you would expect instead?

Considering the index_oc as an example, when changing its control mode i would expect the change to affect only this motor and the joints it moves, i.e. index_prox and index_dist.

Is there any physical robot that uses YARP interface that is actually implementing the behavior that you expect?

I haven't performed any test on the real robots, so I don't have an answer for that.

Can you explain what you would like to achieve in controlling in torque control the hands?

I need the torque control mode for the hands because I'd like to implement a force control for the fingers.

[traversaro]

which behavior do you would expect instead?

Considering the index_oc as an example, when changing its control mode i would expect the change to affect only this motor and the joints it moves, i.e. index_prox and index_dist.

The problem is that at the moment the coupling interface does not provide any way to expose "subgroups" in the coupling, to understand which "actuated axis" are related to which "physical joints" (let's try to stick to this nomenclature we use to avoid ambiguity, thanks). The possible way to solve this is to either expose somehow this information in the IJointCoupling interface or another interface and then modify the ergocub hand coupling to expose this info, or write a piece of code that queries the coupling to automatically extract this info given the existing interface (for example, by "moving" the "physical joints" position and check which "actuated axis" position changes, and vice-versa).

This is doable, but I doubt there is anyone on AMI or iCubTech side that is available to work on this, especially if this does not reflect the behaviour of a real robot, however I would be happy to help anyone on HSP side that is willing to work on this.

Can you explain what you would like to achieve in controlling in torque control the hands?

I need the torque control mode for the hands because I'd like to implement a force control for the fingers.

Just in simulation or you plan to eventually use the force control on the real robot? I am not sure if the real ergocub hand (and firmware infrastructure) supports that.

[PasMarra]

I would be happy to help anyone on HSP side that is willing to work on this.

Thank you. As for now, I don't know if there is someone available for that on HSP side.

Just in simulation or you plan to eventually use the force control on the real robot?

For the time being, I was planning to use it in simulation, but I eventually want to transfer everything on the real robot.

I am not sure if the real ergocub hand (and firmware infrastructure) supports that.

Yes, actually it is probably not available yet on the real robot either.