Control strategy of a 6-DOF hydraulic shaker

Torsion control strategy of a 6-DOF (degree-of-freedom) hydraulic shaker was presented to improve the control precision of the system. Two torsion control loops were added to the original 6-DOF control loops. The force balance controller was improved based on the torsion control strategy. The number of the controller parameters was reduced from eight to two, and the two parameters were independent and could be adjusted individually. Sine vibration tests were run in one 6-DOF hydraulic shaker with the new algorithm. Test results showed that the torsion control strategy is favorable to improve the performance indices of acceleration evenness degree and acceleration transverse components in the lower-frequency band of the system; the improved force balance controller can reduce the inner forces among the eight cylinders effectively.