IIR filter design and implementation for 2D active absorbing wavemaker system

Wavemakers are essential facilities for physical model tests in coastal engineering field. The working principle of a wavemaker system is generating desired waves by controlling the mechanical motion of wave paddle. The absorbing control system is realized by an infinite impulse response (IIR) digital filter that approximates the transfer function in frequency domain. This paper presents the design and implementation of the IIR filer for a piston-type absorbing wavemaker system in a 2D wave flume. Based on first-order wavemaker theory, a frequency domain absorption transfer function is modeled. Then an IIR filter is obtained by approximating the transfer function with non-linear least square optimization. In practical systems, time delay exists in the control loop. Therefore, a delay compensation term to the transfer function is proposed. Experimental results on a real system show that the system performs well for both regular and irregular waves.