Control Barrier Function-Based Safety Tracking Control for Electrohydraulic Operation Bench with Time-Varying Constraints

In electrohydraulic operation benches (EHOB), one of the significant challenges of advancing toward intelligent control is ensuring operational safety under time-varying constraints, where excessive position or velocity may cause mechanical damage or environmental hazards. The inherent model uncertainties and high-order differential dynamics of electrohydraulic systems make it difficult to directly apply various safety mechanisms. Therefore, a modified state equation is constructed by consolidating matched and mismatched disturbances into a unified input channel. Then, a parallel safety mechanism based on Control Barrier Function (CBF) is introduced without disrupting the underlying ESO-backstepping control framework, which facilitates time-varying constraints to be enforced with merely position measurement. The CBF-based safety approach proactively modifies the intermediate virtual control laws when the actual trajectory approaches the constraint boundary, preserving a sufficient safety margin before violation occurs. Furthermore, a multiplicative disturbance induced by the modified state formulation is handled through an adaptive safety estimation scheme, avoiding velocity-constraint violations and reducing tracking error. Rigorous Lyapunov stability analysis proves that all closed-loop signals are uniformly ultimately bounded and the system states remain within the expanded safe set. Comparative experiments across multiple scenarios, including sinusoidal tracking and arbitrary joystick manipulation, demonstrate that the proposed controller can achieve high-precision position-tracking performance under position and velocity constraints.