Stiffness variations in granular jamming robots; an experimental method

One of the most challenging issues of granular jamming robots is both predicting and measuring the stiffness variations which are a direct function of elastic module. In this regard, in previous researches, it had demonstrated that the elastic module of robot's bulk is a fundamental function of vacuum pressure and must be acquired by experimental tests. However, there was not a unique formulation for both computing and predicting the accurate elastic module in each unique amount of vacuum pressure. Therefore, in this paper, for addressing the problem, the elastic module of jammable segments is calculated in each considered vacuum pressure and we have introduced a both simple and beneficial formulation to predict the amounts of stiffness based on variations of vacuum pressure. The proposed procedure was examined by performing an experimental test as well. On the other hand, the necessity of identifying organic material was felt due to introduction of just one organic granular material in previous researches for applying. Hence, four new organic granular materials were selected and also tested. Consequently, a usable blend of two of them was presented which was mixed of black Pepper seeds and Datura grains. This blend had a lightweight construction with high ratio of strength under external forces, therefore, it can be applied when a both high-strength and lightweight jammable structure in robotics is required.