Research On The Design And Gait Planning Of Wheel-legged Mobile Robot On Unstructured Environment

The unstructured environment robots have the broad foreground and social requirement in the fields like military affairs, celestial body detecting and natural resources detecting. About fifty percent of the surface of earth is covered by dene, marish, massif and so on. Though researchers have invent many kinds of wheeled machine, designing and manufacturing a legged robot like myriapod running in natural environment is still a huge challenge. How to realize stable, rapidity and smooth motion in the unstructured environment, is one of important subjects faced in mobile robot research. Motion in the unstructured environment, not only a compounded mobile mechanism with high environmental adaptability is necessary, but also a self-adjusting gait planning for such mechanism is required.Therefore, a wheel-legged mobile mechanism motion in the unstructured environment and the gait planning based on sensory reflex for the robot are studied in this dissertation. The main contributions of this dissertation are introduced as follows:(1) After analyzed the feature of unstructured environment and the requirements of mobile robot, a kind of wheel-legged military robot is presented for motion on the unstructured battlefield. By combining, the robot has multi-motion modes, such as wheel, leg, pedrail and compounded motion mode. With such mechanism, the robot can exert the advantages of these motion modes under different conditions, to adapt the unstructured environment for completing the tasks of unmanned military robots.(2) With the analysis of legs motion orderliness of quadrupeds, an integrated definition of quadruped gait is brought forward. With the quadruped gait derivative spectrum, we can get the successive transition between the standard gaits. At the same time, the relationship between the gait selection and motion speed was detected. Thus, the ideal gait with the most coordination and minimal energy consumption should be select for different four-legged mechanisms motion with different speed. With these theories, the reference for quadruped robot gait selection is afforded, and the successive transition for gait with motion speed is realized.(3) An online gait planning approach is proposed base on the characterization of quadruped walking. In accordance with the application of gait of motion robot in unstructured environment, the concept of sensory reflex is defined; the posture space and sensor space are mapped to the joint trajectory space directly. In addition, combined with the game theory, it can be made an online gait planning model with sensory reflex and game decision. With this model, the angle of knuckle would be adjusted to cause a calm motion when the robot walking on the unstructured environment.(4) Based on the gait planning of leg motion, the complex motion of wheel-leg of robot was analyzed. The gait planning of multi-motion modes was brought out and the motion capability of the robot motion on the unstructured environment was analyzed.