Tracking control of an electro-hydraulic shaking table system using a combined feedforward inverse model and adaptive inverse control for real-time testing

An electro-hydraulic shaking table (EHST) is used for real-time replication of situations that occur in civil and architectural engineering, the automotive industry, and earthquake resistance testing. EHSTs are able to generate a large force at high speeds over a wide frequency range and this feature makes them invaluable in performing vibration tests. Unfortunately, due to the inherent dynamics of the EHST system's hydraulics, the output response of an EHST system displays magnitude attenuation and phase delays in response to displacement and acceleration commands. A feedforward inverse model (FFIM) combined with adaptive inverse control (AIC) is proposed to improve the tracking performance of the EHST following specified displacement and acceleration commands. The proposed control strategy utilizes a FFIM to extend the EHST system's frequency bandwidth and uses AIC based on a recursive least squares (RLS) algorithm to adaptively adjust the time domain drive signal of the EHST servo controller and improve the tracking accuracy. Experimental and simulation results demonstrate the effectiveness of the proposed combined control strategy.