Shear Strengthened Granular Jamming Feet for Improved Performance over Natural Terrain

Walking on natural terrain like soil and rock is a challenging problem that has been approached from a variety of strategies such as using sophisticated control methods, compliant legs, and compliant feet. In this paper we explore how to modify granular jamming feet for walking applications by adding stabilizing internal structures. Previous work has explored how granular jamming technology can be used to create compliant and stiffness changing feet that enable locomotion over a diverse range of natural terrain by allowing robot feet to conform around 3D multicomponent terrain such as wood chips and gravel and stiffen, preventing slip. To date, no work has been done to tune granular jamming feet for the specific application of walking. We show that adding internal structures to granular jamming membranes can increase the force they are able to resist without slipping by 1.5x while maintaining their ability to conform around obstacles. When attached to a robot, we see increases in speed of up to 1.4x, decreases in the duty cycle necessary to reach desired foot trajectories of up to 5%, and increases in traction force of up to 1.2x over a diverse set of natural terrain.