Design principles for stiffness adjustment in soft material robotics using layer jamming

As companies increasingly face the consequences of an aging population and correspondingly a higher average age of the workforce, the need for support systems for workers is becoming more urgent. In order to allow an effective use of these systems, the worker must be able to integrate these into his daily work and therefore also accept it as an auxiliary system. To improve the safety of the worker and additionally the worker's acceptance of the support system, injury of the employee must be prevented. One approach is the use of soft material robotic systems. A problem that occurs is the trade-off between attainable softness and load-bearing capability. For support systems to exhibit soft behavior and to withstand process forces in other situations, they should be able to change their properties, e.g. the stiffness. This paper gives a short overview about different stiffness adjustment methods and tries to analyze the layer jamming technology as one approach to use in soft material robotic systems. For the technology to be used effectively, influencing factors must first be identified and investigated for the stiffening by means of layer jamming. Tests were carried out on a universal testing machine, which determined the required force for each measurement via a load cell and the corresponding deflection by means of a traverse system. The data determined with the measurement setup was then analyzed and evaluated. Finally, design principles were derived based on the knowledge gained from the experiments. The principles derived from our observations can be used as guidelines for the development of soft support systems.