Design And Research Of Adaptive-joint Wheeled Mobile Robot

Mobile robots,as an important branch of robotics,can replace human beings for exploration and operation in complex and harsh environments such as nuclear radiation,earthquakes,and fires,and have broad application prospects.To successfully complete tasks in an unstructured environment with complex terrain and obstacles,the robot must have good mobility,terrain adaptability,and obstacle surmount performance.Considering the limitations of traditional wheeled mobile robots in obstacle surmounting,this thesis was developed a wheeled mobile robot with adaptive joints,which can passively adapt to terrain changes and climb the vertical steps larger than the wheel diameter.Firstly,according to the terrain characteristics of the robot application environment,the performance index and design requirements of the robot are established.Considering factors such as obstacle crossing,terrain adaptation and vehicle body stability,an articulated rocker suspension is proposed.The rocker can passively adapt to the terrain changes and rotate relatively,and a flexible joint is introduced into the hinge joint to generate resistive torque,so as to improve the stability of the robot.The principle of adaptive terrain of robot is analyzed.The transmission mechanism,flexible joint and damping mechanism are designed in detail.The three-dimensional model of robot is established based on Solid Works software.The strength of key parts is checked through the rigid-flexible coupling dynamics simulation analysis.In order to investigate the robot's moving performance,the mechanism of the robot climbing the vertical step is analyzed,the influence of the traction coefficient on the passing performance of the robot is obtained.The suspension mechanism of the robot is modeled and analyzed,the influence of the size parameters on the robot's obstacle surmount performance is studied,and the optimal size parameters of the suspension mechanism are obtained by establishing multi-constraint conditions.Aiming at the problem that the center of mass of the robot is constantly changing,the position and radius of the center of mass of the robot at any time are derived based on the coordinate transformation method.The simulation analysis of the mobile performance of the robot with Recur Dyn software shows that the front-wheel obstacle crossing is the key stage,which is consistent with the theoretical analysis.The simulation experiment verify that the robot has good terrain adaptability.Through the simulation experiment with and without flexible joints,the rationality of flexible joint design is verified,and the better design parameters are obtained.In order to improve the performance of the robot,the kinematic model of the eight-wheeled robot in the rough terrain is established,and the speed relationship of the driving wheels was obtained based on the analysis of the speed instantaneous center theorem.In view of the instability of the robot climbing the vertical step,the speed of the robot's front and middle-rear wheels in the key stage of climbing the vertical step is analyzed,and the speed ratios of the driving wheels in different obstacle crossing stages are obtained.A multi-wheel speed coordinated control method was proposed and verified through simulation analysis.The uniform speed control mode was simulated and analyzed,and a better driving speed value was obtained.Finally,the construction of the physical prototype is completed.Through a variety of terrain environment tests,it shows that the adaptive-joint wheeled mobile robot has good obstacle surmounting and terrain adaptability,which meets the design requirements,and has a certain reference value for its further research and application.