Controlling jumps through latches in small jumping robots.

Small jumping robots can use springs to maximize jump performance, but they are typically not able to control the height of each jump owing to design constraints. This study explores the use of the jumper's latch, the component that mediates the release of energy stored in the spring, as a tool for controlling jumps. A reduced-order model that considers the dynamics of the actuator pulling the latch and the effect of spring force on the latch is presented. This model is then validated using high speed video and ground reaction force measurements from a 4 g jumper. Both the model and experimental results demonstrate that jump performance in small insect-inspired, resource-constrained robots can be tuned to a range of outputs using latch mediation, despite starting with a fixed spring potential energy. For a fixed set of input voltages to the latch actuator, the results also show that a jumper with a larger latch radius has greater tunability. However, this greater tunability comes with a trade-off in maximum performance. Finally, we define a new metric, 'Tunability Range,' to capture the range of controllable jump behaviors that a jumper with a fixed spring compression can attain given a set of control inputs (i.e., latch actuation voltage) to choose from.