Development of HAFF-A Hand with Active Force Feedback

The problem of grasping by automated hands is often approached with tacit assumptions that the object to be grasped remains stationary and that the fingers can be positioned with perfect control of force and loction of every element in contact with the object.Derivating from the above assumptions, the thesis addresses the problem of going from "no-grasp" to "grasp" with impact, for a 2-fingered 4-dof planar hand.

In the cotrol strategy for grasping an object, position control of the joints is used to locate the fingertips in proximity of the object.Subsequently, the fingers switch to force control mode.the fingers then accelerate and one of them impacts the object.The object moves forward, propelled by the first finger and comes in contact with the second finger after a finite amount of time delay. In other words, during the transistion from "no-grasp" to "grasp", impact generally occurs. we have derived equations to analyze the two impact situations on going from "no-grasp" to "grasp", for a 2-fingerd 4-dof planar hand.

During the course of this work we have designed and developed a 2-fingered 4-dof planar Hand with Active force Feedback(HAFF).The fingers use strain gauges for force feedback.We present a formulation for determining the fingertip forces from strain gauge reading through a matrix estimated for the hand. The complete hardware and the interfacing software for HAFF has been developed.

Shyamanta Hazarika is currently doing his Ph.D. at U. Leeds.

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