A variable buoyancy control system for large UUV

Long voyage, multi-functional and intelligent large unmanned underwater vehicles (UUVs) has been a very important development branch of underwater robots, while the variable buoyancy control system is the key system that controlling the balance and attack angle of UUV. Comparing with small UUVs, large UUVs suffer from the following drawbacks: 1) intense electromagnetic radiation interference caused by high power motors, 2) when using centralized control system, cable wiring is difficult complex and unreliable. To solve these problems, this paper proposed a distributed variable buoyancy system which based on the CAN communication. The system is composed of two parts. One is the main controller which specializes in task management. The other is the slave controller which specializes in action execution and data acquisition. Because the use of high reliable CAN bus as communication physical layer between the two parts, wiring is simple and has good resistance to electromagnetic interference. According to the designed principle prototype working undersea, the buoyancy regulating ability is approximately 300kgf, the maximum adjustment rate is 50kgf/min, the regulating error ≤0.2kgf, and it have the functions of independent diving control, adaptive buoyancy balance compensation and attack angle adjusting. The full functions of the prototype with a large UUV performed well during the sea test.