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Bioinspired Sinusoidal Finger Joint Synergies for a Dexterous Robotic Hand to Screw and Unscrew Objects

Karnati, Nareen
http://rave.ohiolink.edu/etdc/view?acc_num=akron1342458391

Abstract Details

2012, Master of Science, University of Akron, Mechanical Engineering.
This work deals with the complex task of unscrewing and screwing a threaded bottle cap with a dexterous anthropomorphic robotic hand in two cases: i.e, with the thumb-first finger and also with the thumb-little finger. To that end, human motion profiles of nine test subjects were recorded while unscrewing and screwing a bottle cap with five different orientations of their hand with respect to the bottle. Results showed that the periodic motions exhibited by the finger joints shared a common frequency for each subject, but differed in amplitude and phase. From the gathered data, a set of sinusoidal trajectories were developed to approximate this motion for a robotic hand. Because the joint trajectories share the same frequency, a family of sinusoidal inputs can be used in the path planning of the robot to unscrew and screw threaded objects. This significantly reduces the computational cost and complexity of the task. Additionally, the unscrewing data appears highly similar to the mirror image of the screwing data. This implies that the transition to or from screwing or unscrewing motions can be achieved simply by increasing or decreasing the time vector within the family of sinusoids. Simulation results show that the developed sinusoidal trajectories show a close correlation with the motion profiles seen from human experiments. Furthermore, this solution is broadened to two cases. Case1: objects with wide variations in diameters by relating joint angle offsets of the hand to diameter size through the forward kinematics equations. Additional experiments are performed with different object diameters to show the versatility of the concept. The sinusoidal trajectories are all implemented within a PID sliding mode controller to ensure overall system stability. Using the developed sinusoidal joint angle trajectories, the robotic hand successfully unscrewed and screwed four different objects in all trials conducted with each object diameter size. Case2: An adaptive synergy controller is presented which autonomously modulates the finger synergies of a dexterous robotic hand according to the relative orientation of a grasped object. The adaptive synergy controller is derived from approximating the human motion of unscrewing a bottle cap with sinusoids to replicate the task with a robotic hand. Data from human experiments were used to develop an adaptive synergy controller that autonomously modulates the artificial robotic finger motions in accordance with the orientation angle of the manipulator with respect to the grasped object. By choosing appropriate phase and amplitude parameters for the sinusoids used to drive the adaptive synergy controller, the complex motions involved in performing this task can be controlled by a single input. Experimental results of the adaptive synergy controller show that the control strategy successfully allows a dexterous robotic hand to unscrew and screw objects in multiple orientations using only a single input.
Erik Engeberg, Dr. (Advisor)
Abhilash Chandy, Dr. (Committee Member)
Jiang Zhe, Dr. (Committee Member)
116 p.
Biomedical Engineering; Mechanical Engineering; Robotics
Synergies; Shadow Hand; Adaptive Controller; PID Sliding Mode Controller

Recommended Citations

Citations

  • Karnati, N. (2012). Bioinspired Sinusoidal Finger Joint Synergies for a Dexterous Robotic Hand to Screw and Unscrew Objects [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1342458391

    APA Style (7th edition)

  • Karnati, Nareen. Bioinspired Sinusoidal Finger Joint Synergies for a Dexterous Robotic Hand to Screw and Unscrew Objects. 2012. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1342458391.

    MLA Style (8th edition)

  • Karnati, Nareen. "Bioinspired Sinusoidal Finger Joint Synergies for a Dexterous Robotic Hand to Screw and Unscrew Objects." Master's thesis, University of Akron, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1342458391

    Chicago Manual of Style (17th edition)

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© 2012, all rights reserved.
This open access ETD is published by University of Akron and OhioLINK.