A Soft Robotic Hand Pad with Active Balancing Contact Force of All Fingers

Grasping by robotic devices for manipulation and transposition is one of the fundamental and ubiquitous tasks in various domains, including industrial, food and medical fields. Grasping safety is crucial for manipulated object, especially for brittle item or biological target. Thus, contact force, which is a vital factor for grasping safety, has been studied for decades. From the angle of view of system structure design, various kinds of soft gloves are proposed for reducing grasping contact force. However, existing soft gloves are designed to drive fingers from the back of the hand, without considering contact force between finger and manipulated object. The forces between five fingers and object are not equal and often big differences exist between forces on fingers. Aforementioned emerging soft graspers with multiple fingers lack study on balancing contact force of all fingers. Thus, in this paper, a soft hand pad is designed to balance contact force between all fingers. A balancing force control algorithm is developed, which can fulfill balancing force control through adjusting air-pressure of fingers during its grasping object. Experiments verify the proposed soft hand pad design, and the balancing force control algorithm.