Locust-inspired Jumping Mechanism Design and Improvement Based on Takeoff Stability

Locusts keep their bodies moving in a straight line during the takeoff and maintain the body stable during the whole jumping with small pitching motions, ensuring both kinematic and dynamic stability to reach their intended destinations. Inspired by locusts' jumping performance, the Stephenson II six-bar jumping mechanism is adopted to mimic the kinematic stability of locusts' takeoff and a dynamic model is developed to analyze the impacts of the torsional spring location, the spring stiffness and the location of the equivalent body bar centroid on the jumping performance. Furthermore, a revised eight-bar jumping mechanism is proposed to solve the difficulty in realizing dynamic stability using the six-bar mechanism, as the moments of momentum of each component around the overall centroid are positive and contribute together to the counterclockwise rotation of the jumping. The dynamic modelling shows that the mass of the equivalent tarsus bar plays an important role in realizing the dynamic stability for the eight-bar jumping mechanism. Finally, two kinds of jumping robots are designed, fabricated and tested with jumping performance recorded by high-speed cameras, which validates the impacts of the mass of the equivalent tarsus bar on the jumping stability in the eight-bar jumping mechanism.