Due to high impact forces and low duty cycles, monopedal jumping robots are particularly susceptible to failure from a slipping foot. Spines provide a solution to reduce slip, but there has been little research on how to effectively engage them into a surface with a dynamic jumping robot. Previous robots utilizing spines operate in different regimes of surface approach speed and cycle time. For a penetrable substrate, spines must be directed into the surface at suitable holding angles, then extracted before the foot leaves the ground. We accomplished this by designing a gripper mechanism for the robot Salto that pushes in angled spines along their length and is kinematically constrained to engage/disengage with leg crouch/extension. The resulting mechanism introduces no new actuators, enables jumping on penetrable inclines up to 60°, and enables static adhesion to hold 7.5 times the robot's weight from a ceiling.

Collapsible leg spines found on insects and spiders provide a passive mechanism for increased traction while running over complex terrain. In this paper we use this architectural advantage as biological inspiration to increase the useful work in pulling a load with a VelociRoACH, a high speed terrestrial robot. These spines exhibit anisotropic properties in the fore-aft and lateral directions, with a 2:1 holding-to-release force ratio on corkboard (0.2 N to 0.1 N). This increase in effective friction coefficient at the foot-to-surface contact points has decreased the Cost of Pulling for the VelociRoACH by ten times, allowing it to transport loads using less energy. The VelociRoACH with spines is able to engage the surface and pull up to 0.36 N whereas without spines it slips while pulling 0.2 N, demonstrating that the robot's performance with spines is now torque limited rather than friction limited. The spines also allow the robot to remain dynamically stable and resist torque disturbances.