Low-pressure Soft Inflatable Joint Driven by Inner Tendon

We propose a soft inflatable joint for soft robots. The joint can work with low-pressure air pumped with a blower and is actuated by inner tendons. This blower-inflated structure consists of cylindrical links and joints made of the same soft material. A patch is installed around the pivot to secure the range of motion. We provide a theoretical model of the inflatable joint for comparison with the experimental data. We test inflatable joints with diameters of 0.3 and 0.4m with inner pressure of 100, 150 and 200Pa. The results show the relationship between the tension force, flexion angle, and position of the inner tendon under different pressure conditions. We find that the joint mechanism exhibits a recovery force proportional to the bending angle. This study provides a soft and lightweight inflatable joint mechanism integrated with internal tendons for soft robots.