Non-Linear Direct Joint Control For Manipulator Handling A Flexible Payload With Input Constraints

In this paper, we propose a non-linear control strategy for a robotic manipulator handling a flexible payload in the presence of input constraints and input disturbances, which does not require end-point boundary control. The dynamics of the system is described by coupled ordinary differential equation (ODE) and partial differential equation (PDE). Considering actuators saturation, hyperbolic tangent functions and secant functions are adopted to tackle the input constraints. Based on the disturbance observers, the control strategy can regulate the angular position and suppress the elastic vibration simultaneously. The asymptotic stability is proved by the LaSalle's invariance principle. Finally, numerical simulations are carried out to demonstrate the validity of the direct joint control scheme.