Acceleration harmonic identification algorithm based on the unscented Kalman filter for shaking signals of an electro-hydraulic servo shaking table

Abstract

Since there are nonlinearities in an electro-hydraulic servo shaking table, when the shaking table corresponds to sinusoidal shaking tests, its response contains higher harmonics, resulting in harmonic distortion and deteriorating the control performance. It needs to provide harmonic information for harmonic cancellation. The purpose of the paper is to develop an online acceleration harmonic identification algorithm for the shaking table. The unscented Kalman filter is applied to achieve this task. A nonlinear state space of the sinusoidal acceleration response is built for the unscented Kalman filter, which estimates the state of the nonlinear model, and the amplitude and phase of each harmonic, including the fundamental, can be directly decomposed from the identified state vector. The state transition equation is linear and the measurement equation is nonlinear. The efficiency and real-time performance of the developed acceleration harmonic identification are validated by simulation and experiment, in which the estimation error is further used to testify the estimation accuracy.

Experimental investigation of a compound force tracking control strategy for electro-hydraulic hybrid testing system with suppression of vibration disturbances

“…where m dp is the total mass of piston and load referred to piston, B dp is the viscous damping coefficient, and F g is the acting force generated by the actuator for force control. Defining total flow-pressure coefficient K dce as K dce ¼ K dc þ C dtp and applying the Laplace transform to equations (3), (6), and 7, the displacement of the cylinder for acceleration motion can be written as…”

“…In the EHHT system, the desired acceleration generated by the shake table and the force produced by the auxiliary actuator are applied to the specimen in parallel, and therefore one of the key issues to be solved is to real-time replicate the predefined time history of acceleration and force. However, as the performance of electro-hydraulic systems is associated with many nonlinear factors such as valve dynamics, spherical joint clearance, friction, etc., 5,6 the replication for the force control of EHHT system is always limited. Besides, the motion of specimen caused by the acceleration of the shake table greatly degrades the force accuracy since the acceleration motion will result in the surplus force added on the expected force.…”

Acceleration Harmonic Estimation for Hydraulic Servo Shaking Table Based on Multi-Innovation Stochastic Gradient Algorithm

“…Compared with the field test, laboratorybased structural test is an integral part of the product development process in many fields, such as architecture engineering [4], automobile industry [5], and aircraft [6]. However, the inherent nonlinearities of a hydraulic servo shaking table [7][8][9], such as nonlinear pressure-flow characteristic of servo valve, nonlinear friction of hydraulic actuators, and backlash nonlinearity of mechanical connection, result in serious harmonic distortion when the shaking table is excited by sinusoidal acceleration signals. erefore, it is of great importance to estimate the harmonic information of the hydraulic servo shaking table in a quick and accuracy way.…”

Acceleration Harmonic Estimation for Hydraulic Servo Shaking Table by Using Simulated Annealing Algorithm

“…Due to the above nonlinear factor, the sinusoid acceleration response shows amplitude attenuation and phase delay, which causes waveform distortion. The harmonic distortion deteriorates the control performance of system and leads to system instability [8]. In order to suppress harmonic distortion and precisely reproduce the desired signal, it is necessary to obtain the amplitude and phase of the each harmonic component.…”