Research On Multibody Dynamics Of Kangaroo-bionic Hopping Robot

Kangaroo hopping is adapted to the complicated and rough ground environment because of its characteristics such as high velocity, less landing area, well stability and low energy consumption. It is believed that kangaroo jumping robot will be widely used in the field of outer space exploration and military scout in future. In order to obtain a robot mechanism which meets the motion characteristics of kangaroo hopping, the dynamic analyses based on a model established for the kangaroo-bionic hopping robot mechanism, are carried out. The motion elements of kangaroo hopping are revealed and the feasibility for this model of hopping mechanism is validated.Firstly, the international and domestic developmental situations about kangaroo, bionic robot and hopping robot are summarized based on abundant literature reading. The structural and motion characteristics of the kangaroo are studied, and the analyzing methods for robot multi-body dynamics are discussed.Secondly, a single-legged model for 4-rigid-body kangaroo-bionic robot is proposed according to the physiological structure and kinematic characteristics of the kangaroo. The corresponding multi-body dynamic equations and kinematic expressions of the joint driving moment in the stance phase and the flight phase are also established with Lagrange method. The rules of kinematic and dynamic characteristics of the robot are obtained by dynamic simulation analysis with Matlab. Simulation results show that the driving moment for ankle joint is 2.5 times of that for knee joint and 6 times of that for hip joint. This means that the driving moment for ankle joint in the stance phase is the crucial factor for the robot to finish hopping, while knee joint and ankle joint whose driving moment are larger than that for ankle joint are of the function that adjusting the robot flight pose. All of these have offered a theoretical basis for designing kangaroo-bionic hopping robot.Thirdly, the impact model of kangaroo-bionic robot in the stance phase is presented, and the systematic dynamic and kinetic energy equations of this stage are obtained with Lagrange Method. The simulation analyses for the impact velocity in the stance phase, energy loss rate and effects of counterforce, are carried out on the assumption that the motion relationship of robot hopping is deterministic.Finally, a 4-rigid-body model of the kangaroo-bionic robot is established with ADAMS. The dynamic simulations in the stance phase are implemented, and the...