## 1 Introduction  
Technologies that efficiently harness the power of ocean waves are now emerging, setting the stage for ocean waves to become a new major renewable energy source [1; 2]. These technologies have great potential and can be used in tandem, with other renewable energy sources, such as wind and solar, to cater to peak energy demands. Various groups have successfully developed several types of wave energy converters (WECs) at the lab scale, and several models have now been installed in the oceans for commercial testing [3; 4]. In order to permit analytic development, the optimization procedure and control strategy should be considered. The optimization is to determine the parameters of the model geometry and the physical component under constraints [5; 6; 7; 8; 9]. In addition, the control strategy for how to tune the power take-off (PTO) needs to be determined to maximize the consistency of the extracted power in response to the wave variation in height and frequency due to changes in the ocean environment condition from hourly to annually. Initial studies employing the control strategy for WECs revealed that impedance matching provides the theoretical maximum useful energy for a body oscillating in one mode [10; 11; 12]. However, this strategy requires a preemptive knowledge of the body's velocity and/or excitation force of the waves, making it impossible to implement in practice. Furthermore,it requires an ideal (or close to ideal) PTO, which must be able to readily switch between the functional roles of a generator and actuator with high converting efficiency. This in turn would allow control over the sign and magnitude of the hydrodynamic stiffness and the damping coefficient [13; 14]. One of the control techniques that requires a relatively low level of WEC's hydrodynamic information with a reactive energy flow is latching control. This method was first applied to a single heaving buoy [15] and was later also applied to two-body systems [16; 17]. This technique only requires the stopper and not the actuator function of the PTO. However, it does require information regarding peak moments of upcoming ocean waves. Oscillating water column (OWC)-WECs have also been widely studied. OWC-WEC, which is simpler in terms of configuration, was first designed for use in marine navigation [18; 19; 20]. Later, OWC-WEC research mainly focused on fixed systems along the coast [21; 22; 23] and floating systems on the open sea [7; 8; 24; 25; 26]. OWC-WECs essentially consist of a capture chamber, a turbine and an electrical generator. Compared to the moving body types, they have a relatively simple mechanical structure, since there is no mechanical elements, such as a hinge, shaft or linear guide. Incident waves cause the inner water surface level of the capture chamber to oscillate. The reciprocating air flow resulting from the pressure fluctuations in the chamber drives the turbine. The electric generator connected to a turbine rotor then converts the rotational kinetic energy into electricity. The direction and speed of the air flow supplied to the turbine are frequently changed via movement of the waves. As such, an impulse turbine [27; 28] or Wells turbine [29], which rotates in one direction regardless of the direction of air flow, is commonly fitted to circumvent the air to the electricity energy conversion problem in OWC-WEC systems. Efforts have been made to improve the efficiency of OWC-WECs by using a control strategy. However, as an impedance matching control, the PTO module itself acts as an ideal actuator. In OWC-WEC, the self-rectifying air turbine, which functions as the PTO module is unable to work as an actuator. As a result, in order for the impedance matching control to be applied to OWC-WEC, a highly-efficient compressor must be introduced to make its application impractical [30; 31; 32]. [PERSON] et al. [33] presented a latching control strategy for OWC-WEC, which considers air compressibility. [PERSON] et al.