چكيده به لاتين
Robotic hand, as a tool for working in environment, has important roles in various industries applications. Therefore, it would be beneficial to plan and design a mechanism amenable to control the robotic fingers. Since robotic fingers have completely nonlinear behavior and their modeling is associated with the difficulties arising from the factors such as friction, physical features of transmission mechanisms, and changes in hand’s orientation, adopting a model independent to the method of control will be useful. In this thesis, a Takagi-Sugeno-Kang (TSK) fuzzy controller, which adaptively updates its consequence parameters, is employed for position/force control of the fingertips grasping a light and soft spherical object with good precision. In the first step, it is assumed that the hand is stationary and the necessary normal contact forces that produce friction forces, which oppose the weight, were calculated. Afterward, the performance of the adaptive fuzzy TSK controller in maintaining the ball with and without the existence of force measurement noise, external disturbance, and joint friction were evaluated. By comparing the simulation results of this controller with those obtained using conventional non-adaptive computed-torque controller, it was found that the adaptive fuzzy TSK method has a better performance in rejecting unwanted phenomena. The next section of this thesis is devoted to the problem of catching a falling ball. In this regard, the operations of moving fingers were classified as approaching, locking, and holding phases. In the first phase, the fingertips are guided to the contact point through a predetermined Cartesian path within a specific time. Moreover, the force optimization in the locking phase was planned in such a way that the essential impact is exerted on the ball to stop it from falling. In the last phase, the contact forces were set to the minimum oppsite weight of the ball. Finally, in the simulation section, it was shown that the adaptive fuzzy TSK controller is an efficient way for performing ball catching.
Keywords: Robotic hand, Precise grasping, Fuzzy controller, Computed-torque method, Measurement noise, External disturbance, Joint friction, Contact force.
