Miniature Wheel-Legged Mobile Robot

Currently, mobile robots have a rapid development in the whole world, which is widely applied to military reconnaissance, planetary exploration, emergency and disaster releasing, domestic service, etc. Among traditional robots, wheeled robot and tracked robot has relatively simple walking structure and control mode; legged robot or bionic crawling robot has a better adaptive ability of complicated environment; spherical robot has a global shell with a strong recovery capability which will protect its own structure and electrical control system. Based on the advantages of wheeled robot, legged robot and spherical robot, this paper develops a miniature wheel-legged mobile robot. The main content of this paper are the system design of miniature wheel-legged mobile robots, the dynamic analysis of robot kinematics, the study of robotic walking control and the simulation and experiment of robot motion performance.Firstly, based on the structural advantages of wheeled robot, legged robot and spherical robot, the system design of miniature wheel-legged mobile robot is completed. The main configuration of “two parallel wheels + four symmetrically arranged legs + arc wheel shell” is used. The gravity of eccentric weight is applied to driving robot moving; legs match up to the climbing and obstacle crossing; and wheel shell can reset automatically while the robot is overturned. The idea of partial modularization is used to design the driving units composed of small torque motors and reducers. At the same time, leg structures are designed. And according to the structure space of robots, the protection shell is designed to make legs able to be retractable. Considering the demand of automatic reset of robots, the wheel shell is designed. Besides, the key load bearing parts are designed, whose intensity is checked through static analysis. What’s more, sensors and electrical system are introduced.Secondly, the miniature wheel-legged mobile robot motion characteristic is analyzed and the dynamical model of robots is established according to Lagrange equation. The correction of dynamical model is verified through numerical iterative solution of Matlab and Adams simulation. In terms of the motion strategies of robots in different terrains, the climbing and obstacle crossing ability of robot is respectively analyzed in the state of whose legs is shrinkage and extension.Thirdly, the theoretical study and simulation of controllers of robot walking are carried out. And the kinematic model is linearized and changed into state equation. Besides, the correction of state equation is verified through the co-simulation of state equation and Adams system. In the condition of system controllable, a series of controller design and simulation are made. And based on the design of state feedback controllers, robot come to a stable state quickly in the system input condition. The method of expanded variables are adopted to design velocity-tracking controllers, so robot is able to track any speed. The idea of backstepping is adopted to design trajectory tracking controllers which is applied to real-time tracking.Finally, Adams simulation and prototype experiments are carried out in terms of motion characteristic of miniature wheel-legged mobile robots. Robot walking experiments to validate the rationality of gravity driven. In order to verify the strong recovery capability of miniature wheel-legged mobile robots, the simulation and experiments of rollover automatic reset are made. What’s more, through simulation and experiments of climbing and obstacle crossing, the theoretical analysis of climbing and obstacle crossing ability of robots in different states is verified. Through theoretical analysis and simulation, the prototype experiment, the performance index of the small wheel legged mobile robot is determined,The structure and performance parameters of the robot are obtained.