本論文提出一個自適應三指夾爪的設計實現方式，主要有二個部分：(1)夾爪機構及(2)夾爪控制。在夾爪機構上，本論文使用欠驅動機構來設計自適應手指，此設計方法由兩個四連桿機構及扭力彈簧來組成手指，可以根據物件的形狀改變手指的形態來配合物件，達到穩定夾取各種形狀物件的目的。在夾爪控制上，本論文提出了兩種控制：(1)位置控制及(2)力量控制。在位置控制上，本論文設計一個模糊PID控制器，其利用馬達編碼器所得到之當前馬達位置來控制夾爪開合時的形態，使其可以根據使用者夾取各種形態及大小的物體，事先調整適當的手指形態，即可縮短夾爪開合時的週期。在力量控制上，本論文設計一個模糊控制器來控制夾爪的鬆緊度，其利用電流感測器回授夾爪在夾取物件時的電流來決定直流無刷馬達的轉速，根據這些回授計算馬達接觸到物件後的位移量來驗證物件夾取時的鬆緊度。由實驗結果可知，夾爪加入此兩種控制模式後，確實讓夾爪可以更有效的夾取物件。 A design and implementation method of a self-adaptive three-finger gripper is proposed in this thesis. There are two methods, one is the gripper mechanism and the other is the gripper control. In the gripper mechanism design of this self-adaptive three-finger gripper, an underactuated mechanism with a self-adaptive finger is designed so that it can change the shape of three-finger to grip the object based on its shape. In the gripper control, two control types are proposed. One is a position control and the other is a force control. In the position control, a fuzzy PID control based on the motor current position obtained by a motor encoder is proposed to control the grabbing and loosening status of gripper. It can adjust the appropriate gesture in advanced according to the shape and size of object to eliminate the grabbing and loosening period of the gripper. In the force control, a fuzzy controller based on the current obtained by a current sensor is proposed to determine a rotational speed of the brushless DC motor to control the tightness of the gripper while this gripper is grabbing. According to the feedback to compute the displacement after the motor contacts the object, it can corroborate the tightness when the object is grabbed. The more amount of the displacement the tighter the gripper grabs the object. Some experimental results are presented to illustrate the proposed two control types can let the gripper can effectively grab objects.
