Research And Simulation Of The Kinematic Performance Of Wheel-legged Robots

In many occasions,mobile robots can replace human beings to finish high-intensity and high-risk work and protect personal safety.It has great research value and social benefits.Robots working in the field requires to have high athletic performance to fit to the complexity and uncertainty of the terrain environment.The wheel-legged mobile robot is a hybrid mobile robot with high-speed low-power consumption of wheeled robots and high terrain adaptability of legged robots.The high terrain adaptability of robots is often used in unstructured terrain such as field operations,mining,and planetary exploration.The classification research of wheel-legged mobile robots at home and abroad reveals the following features:passive legs and active wheel control,but limited terrain adaptability;leg active and wheel passive terrain adaptability is improved,but control is complex;leg active and wheel active control is simple and the terrain adaptability is strong.However,most of the high-performance motor speed reducer directly drives the joint to control the leg movement.The robot needs to be improved in terms of bearing capacity and energy loss.Combining with the GDA(Gravitationally Decoupled Actuation)method,this paper designs a wheel-legged structure with strong bearing capacity,good motion performance and stable running load,which is applied to the whole mobile robot.Based on the mobile robot,a series of research work is done.According to the principle of reducing energy consumption,the configuration of the wheel legs is determined,the driving motor of the joint is mounted on the robot body,and the movement of the leg is driven by driving the horizontal and vertical mounting ball screws,and the combination of the wheel and the leg adopte hinged and shock absorbers.The structure was subjected to force analysis and kinematics analysis,and the evaluation criteria of exercise performance and mechanical properties were initially established.Establishing the pose model of the single-wheeled leg determines the pose expression of the wheel center point in the vehicle coordinate system.Combining the principle of virtual work and the principle of Hamilton to establish the Lagrangian kinematics equation of the robot provides a basis for the optimal design of the wheel-legged robot.According to the pose model,the enveloping domain of the wheel leg is analyzed,and an optimization model is established to optimize the obstacle performance and maximize the climbing ability.With the help of MATLAB tools,the solution results in improved ultimate climbing performance by 56%,obstacle performance increased by 18.2%,and the parameters of the wheel leg mechanism were deterlined.The gait planning analysis of the four-legged robot is earied out under the condition of satisfying the stability margin.Based on the optimized design parameters,SolidWorks is used to accurately model the wheel-leg structure,and the vehicle envelope domain analysis is carried out for three different layout modes,and a layout pattern with the strongest barrier performance of the vehicle is determined.On this basis,the gait simulation and the simulation of the suspension system are carried out.The simulation results verify the rationality of the gait planning and intuitively show the movement process of the whole cycle.It also illustrates the necessity of the existence of the suspension system,especially in the undulating terrain,which improves the stability of the whole vehicle during the operation,improves the impact load,and lays a foundation for the prototype production and control algorithm.