A Straight Parallel Grasping and Self-Adaptive Gripper with Differential and Watt Linkages

The existing parallel grasping and self-adaptive gripper cannot realize the straight-line trajectory movement at the end finger segment, resulting in a grasping blind zone. To solve this problem, this article proposes a novel self-adaptive and parallel grasping finger, the Watt finger. The finger adopts the Watt linkage to achieve the straight-line movement of the end finger segment, combines the parallel linkages to maintain the fixed attitude of the end finger segment in the initial stage, using a triangular differential mechanism to realize self-adaptive grasping. The Watt finger has a straight parallel grasping function in the initial stage, which is able to grasp things of different sizes on the table. As the first or second finger segment touching the object is blocked, this device automatically enters the self-adaptive grasping state, which can grasp things of different sizes. In this paper, Watt finger is analysed kinematically, and the finger's stable grasping space and a relatively optimized set of parameters are obtained. A new robot hand with two Watt fingers was developed, and experimental results and the theoretical analysis show that the Watt Hand achieves a good straight parallel grasping and self- adaptive effect, and the straight-line trajectory makes the hand have a larger grasping space and a wider range of adaptation.