A Straight Parallel Pinch and Self-adaptive Gripper with Differential and Watt Linkages

The existing parallel pinch and self-adaptive grippers cannot realize the straight-line trajectory movement of the end phalanx, resulting in a grasp blind zone. In order to solve this problem, a novel parallel pinch and self-adaptive finger is proposed, named Watt finger. The finger adopts the Watt linkage to realize the straight-line trajectory movement of the end phalanx, combines the parallel linkages to maintain the fixed attitude of the end phalanx at the initial stage, and uses the triangular differential linkage to achieve self-adaptive grasp. The Watt finger has a straight parallel pinch function at the initial stage, which is suitable for pinch objects of different sizes on the table. When the first or second phalanx touching the object is blocked, the device automatically enters the self-adaptive grasp mode, which can adapt to objects of different shapes and sizes. The kinematics of Watt finger is analyzed, and the stable grasp space and a relatively optimized parameter set of the finger are obtained. A new robot hand with two Watt fingers is developed, and the theoretical analysis and experimental results show that the Watt hand achieves a good straight parallel pinch and self-adaptive effect, and the straight-line trajectory makes the hand have a larger grasp space and a wider range of adaptation.