A three-loop physical parameter identification method of robot manipulators considering physical feasibility and nonlinear friction model

This paper proposed a three-loop physical parameter identification method considering physical feasibility and nonlinear friction model. The full physical parameters can be obtained with physical feasibility by constructing an optimization problem. And the nonlinear friction model which considered Stribeck effect is employed to improve identification accuracy. In the first loop, the physical parameters are identified with a regression model. In the second loop, the nonlinear friction model is identified with a nonlinear optimization method. And in the third loop, the obtained friction parameters are updated and the identification results are to be further optimized. Different from traditional methods like the least squares (LS), weight least squares (WLS) and other optimization methods which can only get base parameters and do not consider Stribeck effect, the proposed scheme can get physical parameters with physical constraints. It is useful in many robotic applications, like model-based control. The Stribeck effect is also employed to improve identification accuracy. The experimental results verified the effectiveness of the proposed method.