Analysis on the fundamental deformation effect of a robot soft finger and its contact width during power grasping

This paper attempts to develop a simple contact model of a robot soft finger which is applied for power grasping. The geometrical relationship between contact parameters such as the deformation, contact width, and touch angle are derived for the developed cylindrical finger of soft material. The proposed nonlinear model of the soft finger deforms on the application of load and contact surface grows correspondingly with an angle. The deformation and contact width are related with contact touch angle, which changes as load varies. The force relationship between contact parameters and geometrical data is then derived. The developed analytical model enables to determine the total contact force at the contact surface during the manipulation. An experiment is conducted with three different hyper elastic materials and the deformations and contact width for various loads are determined. The material properties of finger materials are computed using measured deformation. The suitable soft material for developing robot soft fingers is then selected based on the deformation of the finger and frictional coefficients between finger material and the selected target materials. The numerical simulation is also done for the developed model, and it well matches with the experimental results. The developed soft finger model and its force function can be usefully applied to soft-fingered object manipulations in future.