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Tham khảo tài liệu 'complex robotic systems - pasquale chiacchio & stefano chiaverini (eds) part 12', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 160 Chapter 5. Muỉti-Ềngered hands A survey 144 N.B. Zumel and M.A. Erdmann. Nonprehensile Two Palm Manipulation with Non-Equilibrium Transitions between Stable States. In Proceedings 1996 IEEE International Conference on Robotics and Automation pages 3317-3323 Minneapolis MN 1996. Chapter 6 Grasping optimization and control Grasping regrasping are difficult operations requiring optimal coordination and control of the fingers. Paper gives a concept and applies it to a fourfingered hand. All fingers are equal and driven by hydraulic actuators. Comparison of theory and measurements are convincing. 6.1 Introduction Grasping may be looked at as a process of multiple robots the fingers being in contact with some object. Therefore a description of grasping must include the organization of multiple fingers and in addition the contact phenomena. As grasping by an artificial hand is rather slow we shall neglect in this first approach the dynamical aspects and focus on an optimization of grasping strategies and on the control of a hand with four fingers being modeled kinematically and quasi-statically only. The first step consists in an optimization of the grasp strategy. From trials with five grasp criteria the best one is evaluated. Best performance is achieved by a minimization of the finger force differences with the additional constraints that force and torque equilibrium is maintained that contact remains established and that the finger forces are within the friction cone. Starting with this basic optimization problem various additional constraints are included stability of grasping relative distances between the fingers sliding of fingers and changing a finger s contact position. The last operation is the most difficult one including some more constraints which express the necessities that the new contact point can be reached that the 161 162 Chapter 6. Grasping optimization and control fingers cannot penetrate the object and that no finger has a collision with .
