Abstract:
In order to solve the problem of fast and stable spherical fruit grasping, a novel active three-finger gripper was proposed. A spherical active roller was installed at the end of the finger mechanism. A flexible silicone membrane was attached to the active roller to increase the compliance and friction of the gripper. Each finger mechanism had two degrees of freedom, which can realize the opening and closing of the finger and the rotation of the active roller. The three fingers cooperated with each other during work, and the spherical fruit can be translated toward the gripper under the friction. The spherical fruit can be grasped quickly and stably by only touching it, without the need to precisely control the position and posture of the gripper. In order to illustrate the interactive relationship between the designed active gripper and the spherical fruit, an interaction model between them was derived. Finally, in order to verify the effectiveness of the gripper, tomatoes, apples and oranges were selected as typical spherical grasping objects, and a grasping experiment based on three types of grippers(the active gripper, the fin-ray soft gripper and the parallel rigid gripper) was conducted. The experimental results showed that the active gripper had an average first-time grasping success rate of 96.7%, an average grasping intact rate of 98.3%, and an average task time of 5.9 s, achieving relatively good performance in terms of grasping success rate, grasping quality and grasping efficiency.