Research On Frog-inspired Biomimetic Jumping Robot

The research on biomimetic jumping robot is a forward positional task in robot field. The robot owns the feature of reasonable, agile and high-efficiency in structure and movement like biosome, whose jumping movement could adjust to different ground, realize getting across cannal and obstacle. The robot reveals excellent ability on movement territory and avoiding risk, so it is suitable to achieve the task such as spying, detecting, rescue, anti-terror and so on in non-frame and indeterminism circumstance instead of human. It is important for theory research and has wide application prospect. Frog's jumping movement has the characteristic of strong burst and long distance, the robot that owns this ability could cross obstacle easily and has good adaptability for circumstance. Therefore, this paper selects frog as study target to do research on frog-like jumping robot.Considering that the trajectory and the stance of frog jumping movement are the basis of the research on the biological jumping mechanism of biomimetic robot design, a new method of trajectory extraction from animal's movement is presented. And the 3D coordinate of the joint is obtained after perspective effect and iteration correction. To overcome the shortcoming of large amount of calculation, a program is designed to deal with the video images. And finally the curve of position, velocity and acceleration of each point and the angle of each joint of frog are exported. After the validation of this method, the frog movement information of center of mass and joint is obtained by experiment. Based on the observation and obtained movement information, the jumping movement characteristics and the joint trajectory are analyzed. we find the similar trajectories of hindlimb joints during jump, the important effect of foot during take-off phase and the role of forelimb and hindlimb during jump phase. The force during jump is stuied by dynamic simulation. The analysis result will be used for design and control of frog jumping robot.Based on the analysis of biological characteristics and jumping movement mechanism, frog's complex joint and skeleton structure is simplified. A mechanical model is put forward and the frog jumping robot is designed. The robot's forelimb is simplified as one active shoulder joint and one passive elbow joint for the function of supporting and stance adjusting. The 5-bar lingkage mechanism is used as the main part of the hindlimb, the foot and passive tarsometa-tarsal joint are added for guaranteing the stability of jumping and landing. The two DOFs of coxa joint are used for adjusting the pose, direction and trajectory of jump. The robot could achieve multi-stance to satisfy different demand for jump. The reasonable distribution of quality is helpful for improving efficiency. The hindlimb could realize the movement of jump, leg constriction in air and energy adjusting by single motion, which owns high density of actuator. The 5-bar linkage mechanism of hindlimb cooperated with foot has similar process of the thrust force with frog during take-off phase, which possesses the advantages of low likehood of premature lift-off and low energy loss.The kinematic and dynamic analysis is the base of robot stance adjusting, jumping trajectory planning and real-time control. After direct and inverse kinematic analysis on each phase of robot movement, the kinematic equation is established and the movement space of limb's terminal during aerial phase is studied. The complex forelimb and hindlimb of robot are simplified with virtual work principle for dynamics analysis. Based on the movement model of four limbs, the hindlimb dynamics equation during take-off pahse, the robot kinematics equation during aerial phase, the forelimb dynamics equation during landing pahse, the take-off judgement at off-ground instantaneous and the eversion judgement at touchdown instantaneous are eatablished through the dynamic analysis of whole jump process of robot. The kinematic and dynamic equations are verified by simulation.The jumping trajectory planning is the important method to make robot movement satisfied with the target demand. It is also the base of path planning for jumping robot. Considering that non-line dynamics equation with multi-variable make trajectory planning algorithm to be complex, we first analyze the jumping trajectory, then bring forward the trajectory planning method for multi-parameter and multi-target based on genetic algorithm. The conditions for crossing typical terrain are established. Under the target function of jump stability, security, energy consuming and horizontal distance, the trajectroy planning experiment about crossing canal is done. The method's availability is verified by dynamic computing and simulation.Finally, the control system is desigened based on hierarchical and modularization strategy, which includes upper computer for movement trajectory planning and embedded controller for joint control. Then the experiment about the robot leg, stance adjusting and horizontal jump is implemented, and the jump process is compared with frog. The experiment result proves that the mechanism modle extracted with biomimetic method is valid, and the mechanical design of the frog jumping robot is reasonable and the theory analysis is accurate.