Research On Control System Of Single-legged Hopping Robot Based On STM32

Legged robot is becoming the forefront of domestic and international research direction.As a kind of legged robot,single-legged hopping robot is the only way to study multi-legged robot.Through the study of single-legged hopping robot,we can better grasp the movement law and jump mechanism of the bionic robot.In addition,the dynamic jump gait of single-legged hopping robot is simple,which is an ideal platform for the study of dynamic gait of legged robot.This paper focuses on the design of controller,vertical hopping motion control and robotic hopping experiment of hydraulically actuated single-legged hopping robot.The main work includes:(1)The overall architecture of the embedded control system is proposed,and the hardware circuit of the lower computer is designed with STM32 as the main control chip;The lower computer software is programmed,including the initialization module,the main program module and the interrupt module;The host computer interface is designed in the LabVIEW development environment.(2)The kinematic modeling of the robot is mainly carried out on the joint motion analysis of the robot body with double joint structure.On this basis,the paper proposes a hopping way of the trajectory of the robot in the flight phase of fixed posture and stance phase tracking planning.Two kinds of stance phase trajectory planning schemes based on SLIP model and joint sine model are proposed respectively,and the angle law of joint is obtained by kinematics inverse solution.Furthermore,a joint angle control strategy based on PID is proposed.The PID controller is used in the flight phase,and the PD controller is adopted when it comes to the stance phase,considering the compliance requirement.(3)Experiments of step response and frequency characteristics of the robot in the air are carried out.By setting the parameters of the PID controller in the closed-loop step response experiment,the knee joint and hip joint of the robot are shown to have good dynamic performance;By testing the robot double-joint closed-loop sinusoidal tracking,the knee joint and hip joint frequency characteristics are studied.The experimental results show that the cut-off frequency of knee joint is 6.6Hz,while the hip joint is 4.4Hz.(4)The parameters of the PD controller in the stance phase are set under the conditions of preventing the "twice touch-down" and using different proportion coefficient in the leg contraction and elongation.At the same time,the problem of control strategy switching is discussed,and the judgements of robot landing and take-off are given.Based on the above research,jump experiments based on trajectory planning of SLIP model and joint sine model are carried out.The experimental results show the rationality of the two models.Furthermore,some characteristics of the robot's hopping process are analyzed with the experimental data,which deepens the understanding of the robot's hopping movement.In order to reduce the impact of robot landing,the method of combining changing the trajectory in the stance phase and changing the judgement of robot landing is put forward,and it is proved to be feasible by experiments.Finally,the research work of this paper is summarized,and some research directions are put forward.