Grasp Stability Analysis of an Isotropic Direct Driven Three-Finger Soft Robot Hand

Abstract

Grasp stability is considered to be an important aspect in object manipulation of a multifingered robot hand. Multifingered hand contacts the object at some arbitrary locations during the object manipulation and applies the gripping force to hold and manipulate the object without slip. It is desirable to use the optimum gripping force during the grasp manipulation for two reasons; firstly, to prevent the object from damages, secondly, to decrease the cost of the manipulation. With these objectives in mind, a three-fingered soft hand is designed, and gripping force and stability analysis are done experimentally. DC motors are used to actuate the joints of fingers and force sensors are used to measure the internal force at contact points. PID controller is used to controlling the internal force exerted at the contact points, and the control parameters are tweaked until a satisfactory response is achieved. The minimum gripping force required to handle the object with / without external disturbances is measured. The position variables and frictional coefficients are evaluated from the contact forces at the contact points. In future, the optimization algorithm will be integrated to carry out these tasks in constrained and unconstrained environments.