Research On Gait Planning And Walking Control For Biped Robot

Biped robot technology is one of the frontier research topics in the field of robot research, which is a combination of many disciplines, such as electronic, energy, material and so on. It is an important symbol of high-tech level of a country. Stable walking is the basic behavior of Biped robot, a foundation of other behaviors. Biped robot has great application prospect because of its flexible walking ability. However, Biped robot is a nonlinear system with the features of flexibility, complex structure and strong coupling. The research of gait planning can not only provide theoretical guidance for the design and the optimization of biped robot, but also promote the research and the application of Bionics. Therefore, the research has an important scientific significance and great application value. Gait planning and walking control are the main research contents of achieving stably walking for Biped robot. The gait planning is giving all joints trajectories in order to achieve desired walking for Biped robot in ideal environment, and the main goal of walking control is to improve the gait of robot according to planned gait aiming to guarantee the stable walking. In this dissertation, the research on gait planning and walking control has been deeply done based on collection, collation and analysis of abundant domestic and foreign relevant papers and literatures. The main research work are as follows:(1) Modeling of kinematics and kinetics and stability of Biped robotAfter analyzing the structure of Biped robot and simplifying each joint of the the robot, the link model of Biped robot and the local coordinate of each joint are created. Its kinetics model is deduced according to Lagrange method. Moreover, the definition of walking stability criterion-Zero Moment Point(shorted for ZMP) for Biped robot is introduced, the expression of ZMP is deduced and constraint conditions of satisfying ZMP while Biped robot achieving stably walking is studied.(2) Research on gait planning and its optimization for biped robotIn view of the problems of too high gait valence and oscillate which comes out easily and not large enough ZMP margin when using traditional gait planning, so a gait planning method based on CSI-FSA algorithm is proposed. This method has two steps. The first step is using cubic spline interpolation(shorted for CSI) algorithm to plan the gait of the start walking, periodic walking and halt walking in radial and lateral plane, which containing the distance parameters between Center of Two Hip Joints and the ankle of supporting leg at each key moment. The second step is constructing objective function, which is used to estimate the gait stability, using the distance between ZMP and the center of stable region at each moment of both single support phase and double support phase as an parameter, and optimize the gait which is planned by CSI using Fish Swarm Algorithm (shorted for FSA) algorithm, and try to keep the gait ZMP is as close as possible to the center of stable region. The simulation results show that robot can walk at the ideal gait which has bigger ZMP stability margin than the optimization gait based on genetic algorithm, and the gait is monotonous during each period, and of which the trajectories of the location, angle, angular velocity and angular acceleration are smooth.(3) Research on walking control for biped robotThe gait planning of the robot prototype model and error and the difference between actual walking environment, makes the Biped robot walking stability decline, prone to instability and collapse problem, proposed one kind based on the upper body pose compensation walking control method. The method of double loop control system controlled by foot inner and outer ring on the robot, the inner loop adopts PID control the actual output regulation of each joint angle between the value and the ideal value gap, outer loop control based on the method of upper body pose compensation adjustment Biped people because of environmental factors and instability may ZMP value. The simulation results show that, the upper body pose compensation walking control method and PID control method based on simple compared, can improve the walking stability of Biped robot, robot to achieve the desired stable walking.At the end of this dissertation, the main research is summarized. It makes out the main innovations and research achievements, and also points out the problems and issues which need to further research.