Maximum Dynamic Load Determination via a Novel Robust State-Dependent Differential Riccati Equation

This paper presents a novel application of the differential form of the state-dependent Riccati equation technique (SDRE) i.e., the state-dependent differential Riccati equation (SDDRE) as an indirect solution to the robust tracking control (RTC) problem for determining maximum dynamic load. To address this, the complicated RTC problem is solved indirectly through introducing a parallel sub-optimal problem. Minimising a modified performance index, the uncertainty and disturbances are effectively handled, as well as establishing a compromise between error reduction and small control effort while maximising-load carrying capacity. To overcome the challenges associated with directly solving the uncertain state-dependent differential Riccati equation (USDDRE) for complex systems, a modified Lyapunov-based approach is developed. Additionally, a stability proof is provided for the proposed controller. The proposed controller is then applied to a flexible joint-selective compliance articulated robot arm (FJ-SCARA) carrying a load to demonstrate both its superiority and robustness.