A Novel Nonlinear Disturbance Observer Embedded Second-Order Finite Time Tracking-Based Controller for Robotic Manipulators

Robotic manipulators are complex and dynamic nonlinear mechanical systems subject to numerous uncertainties, such as payload variations, frictions, and unmodeled dynamics. To mitigate the uncertainty caused by these disturbances and minimize the tracking errors of the controllers, this study proposed a finite time tracking-based controller (FTC) that embeds a (NDO) and a second-order sliding-mode modifier (SOSM). The NDO was incorporated to compensate for the system's global bounded uncertainty and the SOSM used a robust nonsingular terminal sliding-mode modifier to stabilize the controller. The theoretical analysis showed that the tracking error could quickly converge in finite time. Simulation on a typical robotics manipulator demonstrated the practical appeal of the proposed scheme.