Design And Research Of Metamorphic Disability Assisting Wheel-leg Composite Robot

The affairs of disabilities people have been included in National Economic and Social Development Master Plan,and also in the National Human Rights Action Plan.The happiness and sense of security of disabilities people is attracted more and more attention,and convenient outdoor activities of disabilities people has become a hot research topic.With the goal of improving the efficiency and environmental adaptability for the disabled people in outdoor activities,the research on the wheel-legged composite robot was carried out,so that the disabled people could switch between the two motion modes of walking and wheeled movement in the activities.Added the cellular structure to the parallel mechanism of mechanical legs,the robot could be selected the appropriate mechanism configuration according to the actual road conditions,so that its multi-function and multi-task needs could be met.The robot’s flexibility,stability and environmental adaptability could be improved,and the complicated outdoor environment to disabled people travel inconvenience problem could be solved.The main research contents are as follows:(1)The configuration analysis of the robot leg parallel mechanism was carried out.Based on the initial configuration of 3-UPS,the kinematically decoupled configuration of2UPS+UPU was obtained by the decoupling optimization of the mechanism.The mechanism was taken as the leg parallel mechanism of the mechanical leg,and its degree of freedom was calculated.The kinematic performance of the leg parallel mechanism was analyzed,and the equations for calculating the displacement of the moving pair and the rotation angle of the rotating pair were obtained by using the inverse solution of the position.The velocity Jacobian matrix of the mechanism was derived.The kinematics equations were solved with MATLAB software,and the results were verified from the simulation process with ADAMS software.The working space of the leg parallel mechanism was drawn by numerical solution method,and the relationship between the volume of the working space and the structural parameters was analyzed.The dimension parameters of the mechanical leg were optimized.(2)The cellular structure,the structure of wheel-foot conversion device and the layout scheme of mechanical legs on the fuselage were designed,and the three-dimensional model of the robot was drawn.According to the performance requirements of the robot in different working stages,the cellular rules of the leg parallel mechanism were formulated,and the conversion scheme between the two motion modes of the robot was designed.The static balance equation of mechanical leg was established,and the static simulation analysis was carried out with finite element analysis software of ANSYS.Aiming at reducing the overall weight of the robot and considering the constraints of the actual structure,the structure of the mechanical leg was optimized.(3)The gait of the robot when it walks on the flat ground and in the rugged environment were planned,a combination gait with strong obstacle-crossing performance was proposed,which was applied to cross obstacles such as ditches and steps.Based on the principle of stability margin,the static stability and dynamic stability of walking robot were analyzed.The foot trajectory of the robot was planned,and the foot trajectory curve of walking on flat ground was obtained by sine function method,and the foot trajectory curve of crossing obstacles was obtained by compound curve method.(4)The virtual prototype of the robot was established,and the ADAMS dynamic simulation software was used to simulate the walking and wheeled movement of the robot in the common outdoor terrain.The walking includes flat walking,crossing ditches and crossing steps;the wheeled movement includes climbing and turning to avoid obstacles.The change curve of displacement,speed and acceleration of the moving pair driven by the mechanical leg and the change curve of angle,angular speed and angular acceleration of the driving rotation pair were drawn.The torque changes of the hub motor and the steering motor were measured during wheel movement.The stability of the robot was analyzed by the displacement of the body centroid in X,Y and Z directions.With the design and research of the compound robot with deformed wheel legs,a new way of thinking for the activities of disabled people was provided,and the application range of parallel deformed mechanism in real life scenes was extended.