Whole Body Manipulation
Fumihiko Asano, Dr. Eng.

Abstract
 Recently, powerful and skillful robotic systems for human power assist and cooperation have been expected widely. Unlike present industrial robotic manipulators, such human-friendly robots should interact with us humans using not only the end-effector but also whole arm and body surfaces skillfully in dynamic environment and various situations. Based on the observation, we have studied modeling and bio-mimetic control of a 3d 8-dof whole arm dynamic cooperative manipulation system using sensitive skin for a sphere object. The control law is designed based on integration of voluntary and reflex movement considering the system's redundancy. The voluntary task for holding objects is considered as an impedance control at the four contact points with the object using the contact force information of the sensitive skin, and reflection is introduced as a regulation problem of the direction between the points of end-effectors and elbows. The solution for control is formulated and derived from the optimal control point of view. We then extend the control law to the case using the body link and modify the control functions in order to adapt external forces of various directions. The validity of the proposed method is investigated by numerical simulations.


Keywords
 Bio-mimetic control, Cooperative control, Whole arm manipulation (WAM), Whole body manipulation (WBM), Redundancy, Voluntary movement, Reflex, Combined motion, Sensitive skin, Impedance control


Our approach
 Generally, cooperative manipulation requires the simultaneous control of both the object's position and the internal force. In our approach, however, we propose novel design technique for dynamic cooperative manipulation using whole arm surface, and mainly treat task distribution for stable grasping. To hold a big and heavy object softly and safely, human can realize multi-point soft interaction between the arms and the object, in addition, by combining voluntary movement and reflex, human can reduce the influence from external disturbances and solve the redundant dof problem at task level within real-time. Based on these bio-mimetic studies, in this research, we propose a control law by integrating voluntary movement and reflex considering the system's redundancy. The voluntary task for holding the object is realized by a whole arm's impedance control at the four contact points with the object using the contact force information of the sensitive skin. The reflex is introduced as a regulation problem of the direction between the points of end-effectors and elbows in order to determine the robotic system's posture uniquely and grasp the object safely without dropping. The solution for the combined motion control is formulated and derived from the optimization point of view by introducing a criterion function. In our simulation studies, we first investigate the control effect in the presence of external forces and propose an adjustment of the reflex to make the system robust. Secondly, we consider a realization of robust and various dynamic manipulation using not only the whole arm but also the interaction between the body and the object. In this case we further adjust the voluntary function in order to adapt to the external forces from various directions. The validities of these approaches are investigated via numerical simulations.
It is understood that this research area still leaves many problems to be discussed and solved, for example, how to model of friction effect and viscoelastic and deformable objects, how to manipulate them by robotic arms skillfully in the presence of arm frictions as well as soft propriety of sensitive skin, how to treat various shape and multi-link objects, etc. These problems should not be ignored for practical use, whereas our study focuses on the mathematical formulation for dynamic cooperative manipulation rather than detailed discussion about the system's practical application. Although several assumptions about the robotic system are a little unrealistic as described in the next section, we leave a detailed discussion about them for another opportunity. The purpose of our study is limited to establish a basic theoretical concept of cooperative dynamic WAM, and throughout this paper we will study the importance of bio-mimetics. It can be observed from redundant human motions, that a skillful manipulation of human is not generated by simply using the mathematical technique of pseudoinverse but rather to divide the redundancy into multi sub-tasks, partial dof is used for the voluntary movement for example to move the objects as desired; and the rest is used for the reflex with respect to the external forces. The final task realization is through combination of each sub-task. In this research, we call the desired task realization and the postural maintenance against external forces respectively as ``voluntary movement'' and ``reflex''.


Acknowledgment
 This research project was sponsored by Bio-Mimetic Control Research Center, The Institute of Physical and Chemical Research (RIKEN) . It is a pleasure to acknowledge the hospitality and encouragement of the members of environment adaptive robotic systems lab., especially Dr. Zhi-Wei Luo and Prof. Masaki Yamakita .


Publications
  1. F. Asano, Z.W. Luo, and S. Hosoe, "Whole Body Manipulation Based on Sensitive Skin," Proc. of the Annual Conf. of the Robotics Society of Japan, CD-ROM, 1H31, 2002. (In Japanese)
  2. F. Asano, Z.W. Luo, M. Yamakita and S. Hosoe, "Dynamic Whole Body Manipulation Under Arm Friction," Proc. of the 45th SICE Joint Conf., CD-ROM, 1A1-A3, 2002. (In Japanese)
  3. F. Asano, Y. Saitoh, K. Watanabe, Z.W. Luo and S. Hosoe, "On Dynamic Whole Body Manipulation," Proc. of the IEEE Int. Symp. on CIRA, pp.1201-1206, 2003.
  4. F. Asano, Z.W. Luo, M. Yamakita and S. Hosoe, "Dynamic Modeling and Control for Whole Body Manipulation", Proc. of the IEEE/RSJ Int. Conf. on Intelligent Robots and Systems (IROS), pp. 3162-3167, 2003.
  5. F. Asano, Z.W. Luo, M. Yamakita, K. Tahara and S. Hosoe, "Bio-Mimetic Control for Whole Arm Cooperative Manipulation", Proc. of the RoboMec, 1A1-L1-32(1)-(4), 2004. (In Japanese)
  6. F. Asano, Z.W. Luo, M. Yamakita and S. Hosoe, "Whole Body Manipulation by Integration of Voluntary Movement and Reflex," Proc. of the Annual Conf. of the Robotics Society of Japan, CD-ROM, 3C26, 2004. (In Japanese)
  7. F. Asano, Z.W. Luo, M. Yamakita, K. Tahara and S. Hosoe, "Modeling and Control for Whole Arm Dynamic Cooperative Manipulation", Proc. of the IEEE/RSJ Int. Conf. on Intelligent Robots and Systems (IROS), pp. 3282-3287, 2004.
  8. F. Asano, Z.W. Luo, M. Yamakita, K. Tahara and S. Hosoe, "Bio-Mimetic Control for Whole Arm Cooperative Manipulation", Proc. of the IEEE Int. Conf. on Systems, Man and Cybernetics (SMC), pp. 704-709, 2004.
  9. F. Asano, Z.W. Luo, M. Yamakita and S. Hosoe, "Modeling and Bio-Mimetic Control for Whole Arm Dynamic Cooperative Manipulation", Advanced Robotics, Vol. 19, No. 9, pp. 929-950, 2005.

Movie collections
  1. Whole arm manipulation by constant reflex functions (Realtime) [Download]
  2. Whole arm manipulation by constant reflex functions (Slow motion, x0.5) [Download]
  3. Whole arm manipulation by adjusted reflex functions (Realtime) [Download]
  4. Whole arm manipulation by adjusted reflex functions (Slow motion, x0.5) [Download]
  5. Whole arm manipulation with body support by constant voluntary functions (Realtime) [Download]
  6. Whole arm manipulation with body support by adjusted voluntary functions (Realtime) [Download]



Simulation Programs for MaTX
  1. Whole arm dynamic cooperative manipulation of a sphere object
  2. Whole arm dynamic cooperative manipulation of a sphere object with body support

Experiment

Now we are developing our whole body manipulation system which has tactile skin sensors.



RI-MAN



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