The Study Of Omni-directional Static Walking Of A Quadruped Robot On A Slope Based On 4-legs Supporting Period And The Simulation

Today mankind expand their own space,to develope the universe, develope oceans, often use a robot instead of human beings to do dangerous work.In the absence of artificial road environment they can not use the wheeled robot.Foot mobile robot has flexible adaptation on the complex ground,can be conducted in complex terrain walking as well as complete transportation tasks,so widely used in disaster relief and engineering fields.Quadruped robot is the most practical kind of foot mobile robots, has high capacity and good stability of static gait movement.In the current static gaits studies of quadruped robot on the slope,researchers presented an omni-directional static walking pattern that robot parallel to the slope, but in this method, the stability margin of quadruped robot appeared in the case of zero,in the actual movement quadruped robot dumped。In this paper, we analyzed and compared various methods of walking pattern,to achieve rapid,continuous and stable omni-directional static walking on a slope, we took the theory of omni-directional static walking as basis, presented omni-directional static walking pattern that robot keeping plane on the slope, and researched on the stability of walking movement on a slope. By analyzing the causes of the unstable problem, a solution has been proposed. Specific research works are as follows:(1) Study on the omni-directional static walking. First of all, the body posture has been selected, the coordinate system has been set, leg reachable region has been set.According to the offset of the center of gravity, the standard positions of feet have been set, and the positions of CFP have been calculated by the algorithm. Then the static gaits on a slope have been planed:selecting a gait based on the position of the turning center of rotation gait, deriving the positions of feet during the movement planning leg trajectories and so on. Finally the transitions between all the gaits have been implemented and the omni-directional static walking on a slope has been realized. 2) Analysis of stability of the waking on a slope. The method of the analysis of stability used in this paper is Sm(Stability Margin), however the Sm(Stability Margin)is definited on the plane.In the paper,the Sm(Stability Margin)is improved,and the manner of caculating is given,so that it can be used in the judging of the stability that on the slope.Using the Sm(Stability Margin),we analysed the stability of the quadruped robot that on the slope with omni-directional static walking.And stability problems are raised. In response to this instability, we find the reasons of the instability and propose a manner by means of increasing the duty, then we design the walking that with 4-leg supporting period, using this period,robots move the COG in the 4-legs'supporting period to keep the stability margin always lager than zero.The solution gives different ways to move the COG according to the pattern of gait transition.(3) Simulation.In this paper,through walking experiments by a simulator, the validity of the proposed approach has been verified. With increase of duty factor,it has been found that the minimum of the stability margin can be improved significantly in the process of gait transition.Moreover,the result of comprehensive successive gait transition experiment shows that the quadruped robot can walk with positive stability margin,when the approach of moving the COG in the 4-legs'supporting period has been applied.Through the proposed new way,the stability margin can always be kept in a positive value in the static omni-directional walking.