Abstract
A comprehensive dynamic analysis is necessary for improving the position accuracy and stability of industrial robot. However, current analytical models rarely consider the nonlinear friction of joints, which is an important factor affecting the authenticity and reliability of the prediction model. This paper proposes a nonlinear mixed friction model that considers Coulomb friction, Stribeck friction, and viscous friction. Based on this mixed friction model, both a pure rigid body dynamic analysis model and a rigid-flexible coupling analysis model are established, and the angular velocity, trajectory of the end effector are calculated, farther the changes of joint torque with or without friction are visualized. After comparing the calculated results, the Kriging model is used to map the friction parameter relationship between the two dynamic models. This paper also proposes a comprehensive evaluation model, named the motion stability model, which can evaluate both the strength and the stability of the motion. By applying motion stability model, the optimization problem of minimizing internal node displacement under the constraint of volume load is constructed based on the solid isotropic material with penalization (SIMP) method. Compared with the unoptimized results, the structural mass of the studied object is reduced, and both the first-order natural frequency and strength are effectively improved. The dynamic model and optimization method provide important theoretical support for the optimization design of industrial robot.
