Optimized Diving Velocity and Depth Control for Diver's Automatic Buoyancy Control Device

Abstract

AbstractIn this article, the design and multiobjective optimization of a non-model-based proportional-integral-derivative (PID) control system for diver's buoyancy control device (BCD) is presented. Changing and maintaining depth is an essential task in diving, for which the diver typically uses manual control of two pneumatic valves. An effective automatic control of the BCD can be beneficial in specific diving circumstances; i.e., in amateur diving, safety stop procedures, automatic ascending in case of critical life functions of the diver, poor visibility, when both of the diver's hands are required for other tasks, etc. In addition to multiple control problems caused by internal nonlinear dynamics of the BCD hardware, three main control aspects were considered: position or depth of the BCD; vertical, meaning the ascending or descending velocity of the BCD; and air supply consumption. From that, we examined and implemented a combined depth and vertical velocity control, which was configured as a cascaded controller setup with outer depth and inner vertical velocity control loops. Such controller setup could easily implement the specified limitations of the BCD's vertical velocity, which are critical for proper decompression procedure while the diver is ascending. In a simulation environment the optimization of the controller parameters was achieved with a differential evolution global optimum search algorithm. Obtained results were then compared to a manually driven BCD in a simulated environment.