Modeling the Soft Bellows of the Bionic Soft Arm

Abstract

Conventional robots are strong, fast and rigid. Although these properties make them useful for industrial applications, for human machine collaborations they pose a threat. An alternative is provided by soft robots. However, model-based control algorithms for soft robots are not yet at the same level as for conventional robots. Their performance is often limited by their soft materials, which are difficult to model. The goal of this paper is to extend and increase the quality of the existing model for the bionic soft arm while ensuring real-time feasibility. In particular, the focus is on the soft bellows of the manipulator that actuates the robot. In this work, the three-dimensional geometrical problem of the inflating bellows is reduced to a two-dimensional problem that can be efficiently solved in real-time. The solution approximates the nonlinear behavior of the hyperelastic material and is part of a regressor, which then models the driving torque. In comparison to the existing model, the new developed model is able to describe hysteresis effects caused by the material. This increases the overall accuracy of the model. The results are backed up by experimental data.