Effective timing of swing-up motion by a pole-vaulting robot

Elasticity has been used in many dynamic robots because it can regenerate energy or absorb collision shock. However, the role of elasticity has remained only supplementary. Its potential usefulness in dynamic motion is largely unquantified. Therefore, we specifically examine a task with an extremely large elastic element: pole vaulting. In pole-vaulting research, active operations by an agent are known to improve vaulting performance. Previously, we investigated an active bending effect while hanging from a pole in a simulation. These active operations are generated from the body motion. In this study, we specifically examine the effect of inertial force resulting from motion of the body. We hypothesize that swing-up motion performed closer to the pole planting point (i.e. later in timing) improves vaulting performance. We developed a robot that can exert a large inertial force, and conducted pole-vaulting experiments to verify the hypothesis. Results showed that energy loss is less when swing-up motion occurs later. Our results support the hypothesis and indicate that the timing of swing-up motion is an important factor contributing to vaulting performance.