Open Loop Active Control Technique on Segmented Marine Riser Vibration Using Electromechanical Actuator

Recently, works have been focusing on suppression of the segmented cylindrical marine riser vibration caused by vortex-induced vibration experimentally as an open loop active vibration control (OLAVC) model. The main objective of this research is employing the OLAVC theory using double control rods driven by double motors as an electromechanical actuator at two locations which are: control rods located beside (CRBR) and in front–back (CRFBR) to the riser. Passive control technique has been verified before employing the power to the motor for both locations. The electromechanical actuators consisted of double control rods driven by double motors (12 V DC) and connected by couplings. The results revealed that the passive control technique was inadequate to suppress the cylinder vibration in both locations. Therefore, OLAVC techniques were developed with four voltages: 6, 8, 10, and 12 V which are, respectively, equivalent to 50, 75, 83, and 100% of the motor power to rotate the control rods. Eventually, a motor counter-clockwise (CCW) direction of rotation provided a better suppression compared with the clockwise direction. Moreover, an OLAVC system seemed to be adequate to reduce the vibration at all the supplied voltages at CCW direction and the maximum suppression has been obtained at 12 V for all actuator positions and water flow speeds where the maximum vibration suppressed up to 65.13 and 69.81% at the CRFBRP and CRBRP positions, respectively, with superior performance of CRBR position.