Force and slip sensing for a dextrous underwater gripper

This paper presents the design of the fingertip sensing subsystem constructed for use in a dextrous underwater gripper. Two distinct types of sensor were developed specifically for this application, a force sensor and a slip sensor. The force sensor is used to determine the force exerted by the gripper on the target object, and hence allow the force loop closure required for carrying out dextrous manipulation and the handling of delicate marine samples. The function of the slip sensor is to detect the occurrence of slippage between the fingertip and the target. The information can be used in a variety of ways, for example providing a warning system to the force control loop or enhancing the gripper's exploratory capabilities in areas of poor visibility. Two quite different methods of extracting the force data from the sensor readings are presented and evaluated. The performance of the slip sensor is assessed, as is its potential usefulness in acting in tandem with the force sensor.