Abstract: The mathematical model and features of a multi- input-multi-output pneumatic-hydraulic synchronized loading system are studied. By analyzing the dynamic progress of the pneumatic loading subsystem, the main elements are presented, which can greatly affect dynamic characteristic. A compound control strategy is proposed, which consists of robust control based on H∞ theory, synchronization control and coordination control. By means of controlling the electro-hydraulic proportional valve or electro-pneumatic proportional valve of each channel, a proving structure is loaded by 6 hydraulic actuators and 4 air chambers synchronously. Experimental results demonstrate that the compound control law is correct and feasible for the multi-input-multi-output pneumatic-hydraulic synchronized loading system.

Key words: Pneumatic-hydraulic, Proportional compound control, Robust control, Synchronized loading