Dynamically Stable Control Of Bionic Quadruped Robots Under External Impact

Continuous improvement of the adaptability, dynamic performance and load capacity of quadruped robot working in the wild has become one of the focuses of the mobile robot research area. In the open field, the ability for the robot to keep balance under relative big external disturbances is considered basic for the robot’s coming into practical usage, and is also the difficulty in this research field. Technology of the present still stays in the laboratory stage which is low speed, static-stability-oriented, and without disturbance. The academic research of high speed, dynamic stable, and under-disturbance outdoor movement is still on the way.This dissertation takes the high-performance quadruped robot as the subject, considersthe influences of external disturbances to the movement of the robot, and researches with the aim to realize the dynamic stability of the quadruped robot under external impact, the magnitude and direction of which is unknown. Based on the equivalent dimensionality reductionand simplification method that can be applied to the multi-joint, redundant-driven quadruped systemand by way of decoupling the disturbances into different directions, a stability control strategy for quadruped robot under external impact is proposed to further improve the robot’s adaptability and dynamic performance in the space, in hope of laying a foundation for future research of outdoor quadruped robot with better environment adaptability and dynamic stability.From the perspective of the bionics research, this dissertation extends the motion of equivalent model from two-dimensional plane to three-dimensional space based on the locomotion mechanism of four-legged animals. Then a template called the three-dimensional spring-loaded inverted pendulum (3D-SLIP) is proposed and the dynamics equations for flight phase and stance phase are established respectively to provide a model base for the following study of control method. After a further research on dynamic stability control method for the equivalent model, this dissertation proposes the Three Dimensional Hybrid Feedback Control (3D-HFC) which combines the touchdown angle controlmodule, the energy compensation module and the body attitude angle control module. Simulation experiments of3D-SLIP systems under different external impact are conducted to verify the effectiveness of the3D-HFC strategy, providing algorithm base for the stability control of quadruped robot. In order to extend this stability control method for the single-leg and quadruped model which have more active degrees of freedom and complex structure, this dissertation presents an extension application method from simple model to complex model, providing base for thecontrol of the real robot prototype. Further, the single leg prototype platform and the quadruped prototype platform are built respectively. The vertical jumping and lateral impact experiments are designed and implemented on the prototype platforms, and the experimental results show that the quadruped robot system can realize the impact disturbance rejection and achieve a stable balance under lateral impact. The largest impulse of the impact in the experiments can reach120kgm/s.Dynamic stability control is one of the key technologies to improve the dynamic stability and environmental adaptability of the quadruped robots. Research results of this dissertation provides new ideas for dynamic stability control of quadruped robot, and can be extended for the outdoor-oriented quadruped platforms in the future, having its value in potential applications.