Research On Humanoid Robot Gait Planning Of Crossing Obstacle

Robot technology, which is one of the greatest human achievements of thetwentieth century, represents the highest achievement of the mechanical and electricalintegration. Though there are only nearly40years of history, the biped robot, one typeof robots, has become an important development trend in the study of robotics becauseof its unique adaptability and its nature of being humanoid. In recent years, the study ofhumanoid robot with similar shape of human is developing rapidly and it has more andmore human characteristics. Humanoid robots mimic the way of human walking, whichhelps the completion of tasks in coordination with human friendly, especially in humandaily life and work. Compared to other means of moving, biped walking can take theinitiative to choose the best support points by supporting legs to touch the grounddiscretely and alternately, which subjects to less environmental restrictions and thus hasbetter adaptability and flexibility. This superiority is particularly prominent in theunstructured environment, which is one of the reasons why humanoid robot has beenstudied vigorously.However, to make humanoid robot really adapt to the unstructured environment,namely, to walk in the environment with obstacles, it is necessary to consider how therobot goes through the obstacles without contacting or even colliding with them. Therehave been many studies on the path planning of robot who can take a detour to avoidobstacles. This paper does not discuss about it. Instead, this paper mainly analyzes howhumanoid robot goes through obstacles by using the way of crossing them.This paper analyzes the structure of humanoid robot prototype in the laboratory,measures and records its joint geometric parameters. According to the theory ofkinematics and dynamics, a mathematical model of the prototype is established. Theway of robot crossing obstacles is divided into two types: crossing obstacles step bystep and crossing obstacles directly. And this paper discusses geometricconstraints—collision-free constraints when humanoid robot walks in the two types ofcrossing obstacles through the analysis of the structural parameters of the robot andobstacles environment. According to the requirements of the walking stability of robot,this paper also analyzes and discusses the stability constraints of robot, and elaboratesthe concepts of static and dynamic stability.This paper focuses on the planning of movement trajectory and the calculation of joint angle when humanoid robot crossing obstacles and the detailed planning of thewalking gait of robot in the two types of crossing obstacles. First of all, the authoridentifies the key frame based on the geometric constraints in the process of robotwalking. And then, the author gains the trajectory of robot foot-side and centroid usingthe key frame interpolation through cubic spline function. At last, the author calculatesthe movement trajectory of the joints of the lower limbs based on the inverse kinematicsequation. In addition, taking the movement coordination of robot upper and lower limbsinto account, simple planning about the movement of the upper limbs is made.Meanwhile, According to the stability requirements of walking robot, the authordescribes the genetic algorithm gait optimization method based on ZMP stabilitycriterion. Through this method the movement trajectory of the walking robot can begained and thus the robot is able to maintain dynamic stability while walking. Theauthor has simulated this gait planning and the result shows that this method isworkable and effective.