Decomposed dynamic control for a flexible robotic arm in consideration of nonlinearity and the effect of gravity

This article presents a nonlinear dynamic model of a flexible robotic arm considering nonlinearity from elastic deformation and the effect of gravity. The dynamic model can be decomposed into separate flexible and rigid subsystems. A decomposed dynamic control, including flexible and rigid dynamic controls, is proposed for the controller of the flexible robotic arm. Optimization is used in this flexible dynamic control to obtain the desired trajectory and can deal offline with strong nonlinearity, but it is excessively dependent on the accuracy of the model, so it is not robust enough and has poor disturbance-rejection capabilities. The rigid dynamic control, by contrast, is expected to be sufficiently robust to compensate for uncertain factors. Therefore, a hybrid sliding mode control is proposed to track the desired trajectory and further suppress residual vibration. Additionally, the actual flexible modes are estimated to accurately calculate the component of the proposed controller. This study addresses the theoretical derivation and experimental verification of the proposed controller.