Jixie chuandong (Aug 2021)
Nonlinear Stiffness Modeling Method for a Collaborative Robot
Abstract
A nonlinear stiffness modeling method for collaborative robots（Cobots） is proposed， which is combine the finite element analysis method （FEA） with the virtual joint method （VJM）. This modeling method not only includes the linear and coupled stiffness of the link and joint modules， but also takes into account the nonlinear stiffness of transmission systems of robot， the change rate of Jacobian matrix under loads and the influence of the changes of poses are caused by the load and deadweight on nonlinear stiffness of robot. The structure stiffness matrices of link modules and joint modules are obtained by finite element substructure method. Combined with the nonlinear stiffness model of the transmission system， the nonlinear comprehensive stiffness model of each robot module is established. The static equilibrium pose and the force of each module under external force and self-weight condition are calculated by numerical calculation method. Based on the VJM， a nonlinear stiffness model of robot is built， and the validity of this method is proved by nonlinear finite element simulation.
