Humanoid Robot Collision Dynamics Of Lfexible Limbs And Buffering Adjustment

Contact-imp act is the basic condition of cooperation between a humanoid robot and people or between multiple robots. Flexible collision dynamics is the key to the research of contact-imp act problem. When the humanoid robot slips down in unstructured environments, the robot lose its balance is inevitable. This dissertation focuses on the collision dynamics response and buffering adjustment method in the process of slipping collision.First, this dissertation described the development course and the present situation of flexible collision dynamics, numerical calculation and dynamic simulation. It also described the problems and solutions, involved in the dynamics modeling of collision dynamics of flexible robots, and revealed the significance of this thesis.Then, this dissertation established the humanoid robot limb kinematics models of rigid and flexible. Using D-H parameters and homogeneous transformation matrices described humanoid robot limb position and orientation. Flexible deformation was described by the theory of Euler-Bernoulli beam and decoupled by the assumed mode. In order to study the collision dynamics response of the contact-imp act process, contact-imp act model and normal impact force were established by using the Hertz contact theory and nonlinear damping theory. Flexible deformation was decoupled by using the assumed mode and second-order modes. While taking into account the effect of elastic potential energy and gravitational potential energy, collision dynamical equations of the single limb and double limbs were derived through Lagrange equations.In order to contrast different of the flexible limb and rigid limb collision, reference to adult body size, virtual prototype model was built through ADAMS software first. Simulations study had been carried based on the action of clapping hands. The fourth-order Runge-Kutta numerical solution algorithm with variable step-size was designed, to solve the kinematics and dynamics of slipping. The co-simulation platform was established by uniting ADAMS and MATLAB for collision force control simulation.Simulations of different stiffness of flexible limbs under collision response are implemented. The Curves of normal contact force of the flexible robot end, joint angle, angular velocity and the elastic deformation are given and contrasted. Results show that the contact force becomes larger and the peak phase advances, and the flexible robot joint angle after the collision becomes smaller, the rotational angular velocity and the elastic deformation are reduced. Simulations of different damping are carried out too. With the damping, the vibration of the rotational angular velocity and the elastic deformation turn stability changes after a short vibration; without the damping, the vibration turns constant amplitude.Further experiments show that the normal contact force associates with limbs posture. By adjusting the limbs posture to change the overall moment of inertia of the shoulder, thus swing angular velocity of limb is changed to adjust the normal contact force. With the elbow joint flexion-extension angle increasing, determinant of stiffness matrix of upper limbs is going on a downward trend. The buffering time is increasing by reducing the limbs terminal velocity before the collision. Finally, this dissertation establish collision force control model, and through the co-simulation platform for verification.This dissertation realized the whole process of the collision dynamics of humanoid robot flexible limbs through MATLAB numerical algorithm. The simulations describe the collision dynamics, and verify the validity of the model and algorithm. The dynamics and solving algorithm proposed are proper. This dissertation is helpful for the dynamic simulation and control of flexible robots.