Modelling and analysis of a two-degree-of-freedom robot with a flexible forearm

The authors present a nonlinear model for a two-degree-of-freedom robot with a flexible forearm in both the continuous and discrete forms. One axial and two transverse displacements are considered and the second-order terms related to the flexible motion are included. The model also contains external viscous damping on the joints and internal fractional derivative damping in the arm. Based on simulations, a criterion threshold on the angular velocity is proposed to determine whether the nonlinear effect must be included in the study of a particular flexible robot.