Analysis of transient deformation response for flexible robotic manipulator using assumed mode method

Since flexible robotic manipulators has larger compliance, higher speed and lower energy consumption, they have been widely used in mechanical engineering and space and aeronautics fields. Here the well-known assumed mode method (AMM) for the robotic manipulator is reviewed, especially focusing on its capability to calculate the transient deformation responses. In this paper, the dynamic model for two-link robotic manipulator is established by using AMM with the simply supported beam modal assumption. AMM solutions for the deformations of the links are compared with those obtained by absolute nodal coordinate formulation (ANCF). The results show that AMM have good accuracy to predict the displacement of the end of the manipulator because the point trajectory curves obtained by the two methods are coincident. However, the deflection of AMM solution will decrease as the position approaching to the mid-hinge of the link. To be contrary, ANCF solutions show that the more the position approaches to the mid-hinge, the greater the deformation. The error for the amplitude of deflection between AMM solution and ANCF solution exceeds 200%. Hence, AMM is not efficient for analyzing the strength of robotic manipulator.