Sampling eye-head coordination in the iCub search space

[ashrafzia]

Hi Guys,

Am new to iCub. Please ignore any silly mistakes.

Am trying to sample joint values of eye-hand coordination in the iCub simulator.

Previously, i defined a position in the iCubs search space using the cartesian coordinate system, reach their using the right arm and when given the same x,y and z coordinates to the fixation point i can look at it and the head adjusts automatically.

Now, i want to record all values i.e joint angles of the right arm + wrist (7 values), pan, tilt and vergence of the eyes (3 values) plus pitch,roll and yaw of neck (3 values) when given a position (x,y,z coordinates) in the search space which is iteratively updated, so 3 values for the coordinates.
Total ( 7 + 6 + 3 = 16 )

I have the following script to run my program:

#!/bin/sh
gnome-terminal --profile="Default" --tab -t "YarpServer" -e "bash -c \"yarp conf --clean; && yarp server; exec bash\"" \
--tab -t "iCubSimulator" -e "bash -c \"sleep 2 && iCub_SIM; exec bash\"" \
--tab -t "simCartesianController" -e " bash -c \"sleep 3 && simCartesianControl; exec bash\"" \
--tab -t "right_arm Controller" -e "bash -c \"sleep 4 && iKinCartesianSolver --context simCartesianControl --part right_arm; exec bash\"" \
--tab -t "iKinGazeCtrl" -e "bash -c \"sleep 2 && iKinGazeCtrl --from configSim.ini; exec bash\"" \
--tab

I can see the arm configuration when i move to a particular location, in a terminal which i have associated with the right_arm as:

Target rxPose   [m] = -0.400000 -0.400000    0.800000   -0.350747   -0.897678   -0.266741    1.314759
  Target txPose   [m] = -0.220152   -0.006505    0.342514    0.463208   -0.884254    0.059442    1.978500
Target txJoints [deg] = -95.000000   23.780724   61.731054   82.149945   40.205303  -11.674962   6.022538
  norm(rxPose-txPose) = pos [m]: 0.629664
                        ang [*]: 1.09984
    computed in   [s] = 0.042202

Question 1: How can i access or store the above joint angles? that are opened in a separate terminal.

Question 2: What if i define a starting point and a final point in the search space for the arm to move around and that should be followed by the head (eyes+neck)?

Question 3: If the given points are unreachable then what value will be stored?

I have been using the following functions previously:
getPose() -> getting initial configuration of arm
gotoPoseSync() -> moving to a particular location in space along with the acknowledgement.
getFixationPoint() and lookAtFixationPoint() -> for the eyes.

Any guideline or comments if i am going in the right direction?

Thank you

[pattacini]

Hi @ashrafzia

Let me suggest you to use yarpmanager to launch modules: it's much handier than relying on dedicated scripts.

Answer 1

• You can access robot joints (e.g. neck, eyes, arm ...) through the yarp::dev::IEncoders motor interface. See this tutorial to find out more.
• You can easily log and store joints values as they change throughout your experiments relying on yarpdatadumper.

Answer 2

Perhaps I didn't catch your exact point, but the Cartesian space (what you call the "search space") is common to both the Cartesian controller of the arm and the Gaze controller; therefore, you can provide them with the same targets and, as result, the head and the eyes will somehow follow the arm movements.

Answer 3

Arm and Gaze controllers do employ nonlinear optimization underneath that intrinsically deals with unfeasible goals. Thus, if you ask to attain out-of-reach targets, the optimizer will instruct the controller to move to the closest point still reachable.

[ashrafzia]

Hi @pattacini

Thanks for your reply and guidance.

I launched the yarpmanager but could not able to run sample application. I copied the template iCub_Simulator_Startup and saved as my application file because it consists of all the required modules that am going to use.

I get the following error:
[ERR] (iCub_Simulator_Startup) cannot initialize broker. : console does not exist. check yarprun is running as server.

I started yarprun as yarprun --server /SERVERPORT, where can i find the serverport? refreshed application in yarpmanager and finally restarted yarpmanager but still same error.

I also tried yarpmanager-console, issued the comman list app, no applications are showing and list mod, list res etc aren't displaying any result.

I am using a pre-compiled installation. Would that be an issue?

[pattacini]

The xml of the application you want to launch via yarpmanager needs to contain the references to the yarprun nodes where those modules composing the application are meant to run.

In a very minimal setting where you launch every module on your local machine, you could do the following:

1. run yarprun --server /my-pc on your machine.
2. fill in the node tag in the xml file with my-pc.
3. run yarpmanager and open the modified xml file.

In the same scenario, you can profitably rely on the following shortcut, skipping the first step:

1. fill in the node tag in the xml file with localhost.
2. run yarpmanager and open the modified xml file.

Either way, you should be ready to run the application at this point.

If you will still have problems with yarpmanager, to keep this issue on track, please open up a dedicated ticket here: https://github.com/robotology/yarp/issues.

[ashrafzia]

Thank you @pattacini

I have managed to successfully run the module, but the yarpdatadumper_recording_example isn't working. Here is the new issue.

Even if i manage to run data dumper the values for connected elements like head, torso, rightArm will be recorded but how can i track values for (Pan, Tilt and Vergence) of the eyes?

Could it be done the same way as other elements?

[pattacini]

The head part encapsulates both the neck and the eyes encoders according to the following format:

neck	neck	neck	eyes	eyes	eyes
tilt	roll	pan	tilt	pan	ver
neck_pitch	neck_roll	neck_yaw	eyes_tilt	eyes_version	eyes_vergence

The last line refers to the axis names used in the software, as defined in http://wiki.icub.org/wiki/ICub_joints.

[pattacini]

Closing; feel free to reopen if needed.

[traversaro]

I would add to the table of @pattacini that the axis names used in the iCub software (for example the names returned by the IAxisInfo interface or the one used in URDF/SDF files) are [1] :

neck	neck	neck	eyes	eyes	eyes
neck_pitch	neck_roll	neck_yaw	eyes_tilt	eyes_version	eyes_vergence

@pattacini I took the freedom of adding this line to your table.

[1] : http://wiki.icub.org/wiki/ICub_joints#Head_2.0

[pattacini]

Great 👍