Research On The Fast Running For A Humanoid Running Robot

Humanoid running robot has been becoming an international research focus in recent years because it has many advantages of high speed, high-level efficiency, less environment limit and high moving agility over the other mobile robot. In addition, the research on the humanoid running robot can promote the development of other relative subjects. Therefore, it has not only important academic value but also considerable significance of application. However, the running speed of the existing robots that have been developed by some research institute is still very low. It is just the jogging robot. The main reason is the deficiency of the basic theory as well as the absent technology of the actuator. So the relative theories that the robot runs fast are studied in this paper. They mainly include the dynamics with changing topology, analysis of dynamic stability, the running gait planning, the simulation algorithm of whole running procedure and the control method of the humanoid running robot. The detailed description is as follows:1, Aiming at the characteristic of the running, the coordinate system of the robot is built. By using the homogeneous transformation matrix based on Denavit-Hartenberg notation, a kinematic model with three dimensions is presented. The direct kinematics is analized from the reference coordinate system to each part of the robot based on the transformation matrix. For the inverse kinematics, a set of nonlinear equations are firstly built according to the kinematic constraint and the trajectory of center of mass (COM) and two feet of the robot in order to meet the running gait planning. Then the numerical solution of the joint kinematic parameters can be calculated with the Newton-Raphson algorithm. The simulation results show that this method has advantages of high speed and precision of calculation, and it overcomes the shortage of fixing the COM of the robot to the hip joint. So it can be used in real-time gait planing.2, The dynamic model with changing topology of the humanoid running robot is built based on the Cartesian coordinate and Eular quaternion. Since there exists the different kinematic constraint between the stance phase and flight phase, two different dynamic equations in each phase are built. Moreover, the transitional condition from one phase to the other phase is deduced so that global automatic simulation of the robot can be performed. The dynamic equations include the differential equation and the algebraic equation, which has the advantage of high speed and precision dynamic model building because the two kind of dynamic equations can be built easily by modifying a few of theconstraint equations and the Jaccobi matrix. Finally, the change of joint angular velocity of the supporting leg is deduced based on the Lagrange dynamic equation when a foot of the robot collides with the ground.3, Dynamic stability conditions of the robot in stance phase and flight phase are derived based on the D'Alembert principle. Moreover, the condition that the robot does not slip on the ground is deduced according to the reaction force of the foot to the ground when a foot of the robot is in contact with the ground. The two above conditions constitute the dynamic stability condition together when the robot runs.4, Under the circumstance of satifying the dynamic and the stability condition, the running gait planning of the robot is proposed based on the virtual leg, and the running gait with the speed of 2.9m/s is realized succefully by simulation. The trajectory of the COM of the robot in stance phase is determined by solving the dynamic equation of the virtual leg, which can make the robot fly in the air. In flight phase, the COM of the robot moves as a free falling body. Then the running gait can be determined by planning the trajectories of two feet and two arms of the robot. By using this method, the dynamic condition and stability can be satisfied easily. In addition, the running gaits of beginning and ending phase can be planned convinently. In this paper, the running gait of the robot is planned in three dimensions and overcomes the shortage of fixing the COM of the robot to the hip joint, so it has the advantages of high precision and high speed and it is suit for the case when the robot runs fast.5, A global simulation algorithm is introduced for the robot on the basis of the dynamics with changing topology, stability and running gait planning. The whole running gait of the robot is realized succesfully, which begins the standing state, and passes the stating pahse, running phase and ending phase, and ends with the standing state again. The speed of the running gait attains 2.9m/s, which is the fastest running robot available. In addition, the driving torque of robot is smaller and the consumption of energy is lower. Finally, the virtual model of the robot is built by using the software ADAMS, which verifies the effectiveness of this method.6, The control strategies of the forward running speed and the joint driving torque for the robot are proposed. Using the virtual leg, the running speed of the robot is controlled by adjusting the angle between the virtual leg and the vertical line, which can be carried out easily. The joint driving torque is controlled with the impendence control method based on Lagrange dynamic equation of the robot. This method is similar to mankind's instinct control method when he runs, and hence it has many advantages. The joint driving torque, but not it and running speed together, is controlled in the existingresearch. So, the method presented in this paper has its creativity to a certain degree.