Frog-inspired hind limb for jumping robots

Abstract

Frog can jump more than 15 times its body length. This impressive bounce ability movement can be attributed to their hind limbs that transfer elastic energy into kinetic energy rapidly. This paper presents a frog-inspired hind limb mechanism for biometric jumping robots. A robotic design is created to realize the mechanism for the biological hind limb with shape memory alloy (SMA) spring actuators and smart composite microstructure (SCM). SMA spring actuators have advantages over conventional actuators in reducing the size and simplifying the structure. The design employs a unique mechanism that simulates a frog's hind limb kinematics with reduced degrees of freedom. Dynamic modelling is derived and the limb design is optimized through simulations to reach the maximal takeoff speed. A robotic prototype is fabricated that can jump five times its body length.