- 1 "Hand"Some
- 2 Concept and Proposed Demo
- 3 Concept and Task Distribution
We would like to implement impedance behaviours coupling both the hands, hence the bad pun on the name. We would work under the Force Control group and share tools and code with everyone.
You are more than welcome to hack with Us! :D So far, we are YARP and iCub Noobs so any assistance the Wise Ones can give is greatly appreciated.
Participants (so far) :
* Naveen Kuppuswamy "Naveenone" * Cristiano Alessandro "!Alessandro" * Arne Nordmann "North-Man" * Gauss Lee "The Gaussian" * Paolo Tommasino "Pa"O"lo" * Jiuguang Wang "G1"
Concept and Proposed Demo
We believe that the ideal impressive demo should always involve alcohol service, and thus we would like to demonstrate some simple two handed grasp and user directed manipulation of trays with drinks or individual alcohol bottles. Additional tricks can be manipulating objects of various sizes and compliance by playing around with the coupling stiffnes or even adding a cartesian impedance constraint to fit service robot scenarios like serving drinks (keeping bottle upright in cartesian space to compensate for user drunkenness).
Update on Demo
Demo has been scaled down to accomodate for our procrastination. It would involve something like multi-arm coordinated holding of an object like a box..The Control would be demonstrated in both modes (joint space force control, and joint space impedance control) and the user should be able to interact with any one of the arms of the robot.
Concept and Task Distribution
Upon realising the theoritical and practical difficulties in this task we have decided to eat a bit of humble pie and appraoch the task conservatively. We have decided to partition the task as follows :
Phases of the task/demo
Phase 1 : Approach of Object
An assumed object in front of the robot is approached using Joint Impedance Position Control
Phase 2 : Cartesian Impedance Control (Fake and Real)
Object is held by arms using Cartesian Spatial Impedance. This is done is 2 ways:
a. 'Real Cartesian Impedance Control
A Virtual spring assumption is made which generates desired Forces at end effector, and this is converted to desired joint level torques. This can also be called Joint Space Force Control
b. Fake Cartesial Impedance Control
A imaginary line is taken between the arms and the Arms are commanded to maintain their end effectors on this virtual line exerting pressure on a virtual region smaller than the object. This is then sent to a joint level Impedance position control scheme. This can also be called Joint Space Impedance Position Control
To test Phase 2 we will focus on single arm experiments first, wherein, an imaginary point is assumed to be the target of the desired impedance and that is used to test the arm control.