Buoyancy Control for Low-Speed Under-Actuated AUVs

Abstract

An engineering buoyancy control scheme was proposed to compensate the change of residual buoyancy for low-speed under-actuated AUVs. The buoyancy control system is made up of buoyancy controller and two sets of buoyancy control devices include: water tank, sea water pump, valve grouping, pipeline etc. Buoyancy control devices were configured to both head and tail part of the AUV symmetrical to its buoyant center. Depth control algorithm and buoyancy control algorithm were proposed separately. In the process of voyage at a constant depth, the real time speed, pitch angle and depth error were detected to evaluate the residual buoyancy indirectly, and then the real time buoyancy control was executed by pumping the water into or out of the tanks. The buoyancy control scheme was applied to the type of low-speed under-actuated AUV and simulation and experiments results show that the buoyancy control approach and the control laws are feasible and effective.