Research On Trajectory Planning And Landing Stability Of Sole Rotatable Hopping Robot

In recent decades, legged robot has become a hot spot in the field of research on mobilerobot, having a higher theoretical research and application value.Hopping is an important way of movement for legged robot, but it requires that the robotis more explosive with variable restraint. As to the fact that hopping legged robot is a complexdynamic system which is highly non-linear, multi-variable, strong coupling and structurechanging, it becomes a challenging job to achieve obstacle negotiation planning and dynamicbalance control under driving performance constraints. Considering the planar hopping leggedrobot with the motor and spring coupling driver as the research object in this paper, and thepoint that the sole rotates by the tiptoe in the take-off phase and from the perspective ofimproving the hopping ability of the robot, the key problems containing dynamic modeling,hopping gait generation, trajectory tracking control and landing stability are discussed, withmotion constraints combined.Considering the various constraints characteristics of legged hopping robot and solerotation, The hybrid system including continuous dynamic model and collision discretedynamic model is built, and the model dynamical changing conditions can be obtainedthrough research on the dynamic analysis of the passive joints.Aimming at the hopping planning problems in inerratic terrain, the gait generationalgorithm of plane legged hopping robot is proposed. Considering sole rotating, the passivejoint expressions in the complete hopping cycle and the movement constraints in robothopping process are analyzed in this algorithm, and the test on the stable hopping simulationof the planar legged hopping robot is accomplished with optimized thought based on theminimum energy consumption. By the collision in hopping process and under-actuated statein take-off phase, it shows that under-actuated state in take-off phase may increase thetake-off speed effectively and improve the hopping performance, and that hopping withoutcollision could not be achieved considering the performance of the servo motor at present.The legged hopping robot three-bar model with uncertain interference is taken intoconsideration and trajectory tracking controller based on the Nonsingular terminal slidingmode control rate is designed, demonstrating that the designed controller can track the expected trajectory in the limited time. Considering the practical factors of legged hoppingrobot in hopping process, the related simulation of the system model based on Simscape is putforward. The simulation results indicate the effectiveness of the trajectory tracking controllingalgorithm.Based on the robot sole model, the collision stability problem of the legged hoppingrobot with sole rotation in landing phase is analyzed. The stability issues on the landingcollision in legged hopping robot system with sole rotation are related to the stability of theunder-actuated system zero dynamic. Through designing the zero output control rate inlanding phase, the zero dynamic stability problem can be transformed to that of theclosed-loop system dynamic equations. By the research on the closed-loop dynamic equationsand the landing stability parameters, it reveals that the stability problem of the legged hoppingrobot with sole rotation in landing phase depends largely on the structural parameters of therobot and the performance parameters of interface between the sole and the ground.Analysis methods on the planar legged hopping robot dynamic modeling, jumping gaitgeneration, trajectory tracking and landing stability in this paper help improve the exerciseability and flexibility. Also, the methods expand the application areas of legged robot andhave certain reference value in the theory and application.