Fixed-time sliding mode extended state observer-based tracking control for cable-driven parallel robots with uncertain dynamics

The development and applications of cable-driven parallel robots (CDPRs) are restricted due to model uncertainties and external disturbances, which decrease the positioning accuracy of CDPRs. To address this issue, an imitated active disturbance rejection controller (IADRC) is proposed in this paper. A fixed-time sliding mode extended state observer (FTSMESO) is designed to estimate the lumped uncertainties via the switching sliding mode variable. The fixed time convergence of estimation errors is guaranteed, and the convergence time is unrelated to the system’s initial state. Based on the FTSMESO, an IADRC is proposed and its robustness is analyzed. The simulations and experiments are conducted, and the results indicate that the designed FTSMESO effectively observes the lumped uncertainties and verifies the practicality and effectiveness of the IADRC.