Improved impedance control technique for bipedal robot swing leg landing based on switching tree

In the process of dynamic motion of biped robot, the irregular ground touch will occur under the influence of the external environment, and the control efficiency of the unstable support configuration will directly affect the motion stability. The randomization method to set the landing impedance of the swinging leg of the biped robot will cause the overall walking posture to become unstable, resulting in the impact of the foot force of the biped robot. Therefore, an improved impedance control technique for swinging leg landing of biped robot based on switching tree is designed in this paper. The linear relationship between the foot force and the leg length of the swinging leg was analyzed by the five-link model, and the leg stiffness of the swinging leg was determined. The trajectory of the biped robot is adjusted by the feedback force, and a spring physical model is assumed in the position impedance control. Considering the coherence and coordination of the biped robot in the walking process, the switching tree algorithm finds the minimum switching tree and the maximum switching tree of the landing impedance of the biped robot swinging legs, and precisely sets the impedance by determining the optimal node, so that the force of the foot in contact with the ground can change smoothly according to the expected way. newTree is obtained from oldTree from the swinging leg landing motion of the biped robot until no exchangeable tree exists, and the control improvement of the swinging leg landing impedance of the biped robot is completed. The experimental results show that after the impedance control is added to the method, the landing tracking force value of the swinging leg of the biped robot is 5 N, the trajectory tracking accuracy is the highest 99%, the joint Angle deviation is maintained between 0.15° and 0.24°, and the control response time is between 2.35 and 3.02 ms, which can improve the landing stability of the swinging leg of the biped robot.