Design and Depth Control of a Buoyancy-Driven Profiling Float

This paper presents the design and fabrication of a profiling float primarily used for thermocline observations and tracking, with an emphasis on depth control performance. The proposed float consists of a frame-type electronic chamber and a variable buoyancy system (VBS) actuator chamber. Components or sensors can be added or removed according to specific requirements. All components were off the shelf, which lowered the cost of the float. In addition, a segment PD control method is introduced. Simulink results showed that there was no need to change any parameter when carrying out tasks at different depths. This method is superior to the traditional PD control and sliding mode control (SMC). In the process of diving, the speed could be well controlled to less than 0.2 m/s. We completed depth determination and control method validation in Qiandao Lake. The final results were consistent with the simulation results, and the maximum depth retention error was less than 0.3 m. Field tests also demonstrated that the prototype float can be used for thermocline observations in the upper layer of seawater or lake water.

Automated summary

This paper presents the design and fabrication of a profiling float primarily used for thermocline observations and tracking, with a focus on its depth control performance. The proposed float is composed of a frame-type electronic chamber and a variable buoyancy system (VBS) actuator chamber. The article introduces a segment PD control method and shows the superiority of this method in diving tasks at different depths. Field tests validate the depth determination and control method, with consistent results compared to simulations. The prototype float proves to be effective for thermocline observations in the upper layer of seawater or lake water.