Solution of contact pressure between robot edge with soft covering and human body surface considering nonlinear elasticity

Abstract

In building a human-robot cooperative system, it is an important issue to reduce the harm caused by contact with the robot. A protective measure for a robot with a sharp and highly rigid surface is to smoothen the surface shape and reduce the rigidity in order to increase the contact area, and protection with a soft covering is effective. In this research, we focus on the event when the edge of the robot contacts the human body, especially the outer arms or legs. In order to design an appropriate soft covering, it is necessary to estimate the contact pressure between each part of the human body and the edge covered with the soft covering. The contact pressure can be derived from a contact model that considers the curved surface shape of the human body, the radius of curvature of the soft covering and edges, and the stress balance that considers the elastic modulus that hardens the hardness of the human body and the soft covering according to the compressive strain. Then, the validity of the proposed method was confirmed by material experiments to grasp the material properties and experiments simulating contact, using appropriate materials for the contact model targeted in this research. The proposed method can contribute to understanding the tendency of contact pressure by arbitrarily estimating the curvature radius of the edge and the hardness and thickness of the protective covering that covers the surface when applying the soft covering to the edge of the robot surface.

Keywords

• sharp edge
• soft covering
• shape function
• nonlinear elasticity
• contact mechanics
• contact pressure