Research on the Operational Stability and Energy Consumption of the Profiling Float

The profiling float is the crucial component of global ocean observation system. Considering the excessive change rate of motion speed and energy consumption issues during the ascending process of the float, this paper proposes two sets of the piecewise oil-pumping control strategies based on speed closed-loop (SCL) and speed-acceleration double closed-loop (SADCL) respectively. The kinematic model and energy consumption model of the 4000-meter profiling float during the ascending process are established, then the simulation and analysis were made to study the operational stability and energy consumption of the float. By comparing the influence of SCL and SADCL control strategies with that of traditional control strategy for pumping (TCS) on the performance of the float, the results are as follows: SCL and SADCL control strategies can effectively improve the float operational stability and lessen the energy consumption. The amplitude of velocity fluctuation decreased by 65.44% compared with the traditional strategy. When the setting value of feedback speed u(set) is 1m/s, the SCL control strategy is more efficient, saving 18% energy than TCS. However, optimized control strategies will no longer have the advantage of energy saving at the speed u(set) below 0.050 m/s. The conclusion drawn in this paper is beneficial for the further study of the profiling float oil-pumping control strategy.