Static Friction Coefficient Sensor for Controlling Grasping Force

Abstract

This paper deals with the development of a sensor which can acquire the information on the surface roughness of various kinds of objects as static friction coefficient for determining grasping force. The sensor has a simple structure, consisting of a circular plate with rubber surface attached to a DC motor axis. The motor gives a turn to the plate which is pressed uniformly to the object surface by a spring. Static friction coefficient is computed by torque when the motor begins to rotate against friction force. Few sensors of this type to obtain the coefficient have been developed in the past.
The experimental results show that the static friction coefficient for objects with various surface roughness can be obtained and that the coefficient depends on the pressing force for some of the objects with rough surfaces. It was finally verified that grasping force could be controlled by using the detected coefficient adaptively to hold without any slippage an object whose weight was manually changed.