MIMO Adaptive Robust Synchronization Control of an Electro-Hydraulic Dual-Cylinder System With Rotational Dynamics Compensation

Multi-actuator electro-hydraulic systems are widely used in heavy-load applications because of their high power density, structural stiffness, and safety redundancy. In such systems, actuator asynchrony not only degrades position-tracking accuracy but also induces rotational motion of the common payload, internal force interaction, pressure oscillations, and even cavitation. Although existing synchronization methods can reduce relative displacement errors, they often simplify the synchronization-induced coupling dynamics between actuator motion and payload rotation, which limits transient synchronization performance under dynamic operating conditions. To address this problem, this paper develops a rotational-dynamics-compensated MIMO adaptive robust synchronization controller for an electro-hydraulic dual-cylinder system. A dynamic model is first established by jointly describing the translational motion of the payload and the rotation caused by actuator asynchrony, thereby revealing the high-order coupling dynamics, resonance risk, and possible nonminimum-phase behavior of the system. Based on this model, the proposed controller explicitly incorporates rotational dynamics into adaptive feedforward compensation and full-state robust feedback, improving synchronization performance under parametric uncertainties and external load disturbances. ... mehrThree sets of experiments are conducted on a dual-cylinder test rig, including sinusoidal tracking, point-to-point motion under time-varying eccentric loads, and frequency-sweep load-disturbance excitation. Compared with representative cross-coupling and dynamic thrust-allocation methods, the proposed method significantly reduces synchronization-induced rotational errors while maintaining comparable position-tracking accuracy. The results further demonstrate stronger disturbance attenuation and more stable dynamic behavior under different motion and loading conditions. Note to Practitioners—This paper is motivated by heavy-duty machines in which multiple hydraulic cylinders jointly drive a common payload, such as lifting mechanisms, forging presses, electro-hydraulic load simulators, and construction machinery. In these systems, small displacement mismatches between cylinders may tilt the payload, generate internal forces, excite pressure oscillations, or cause chamber cavitation. The proposed method reduces these effects by controlling the payload motion and synchronization-induced rotation together, instead of correcting only the relative displacement error. It uses commonly available cylinder displacement and chamber-pressure measurements and does not require direct measurement of external load forces. By combining online parameter estimation with robust feedback, the method is suitable for machines with uncertain payload mass, changing centroid position, friction variation, leakage, and time-varying asymmetric loads. It is particularly useful during frequent acceleration, deceleration, or eccentric loading, where conventional synchronization methods may produce large transient errors. The method assumes a rigidly connected payload and small induced rotation, which are typical in many lifting and pressing applications. The dual-cylinder experiments demonstrate the present implementation, while the generalized MIMO description also suggests potential applicability to systems with additional actuators, where coordinated motion and synchronization related variables can be constructed from the actuator arrangement.