Research on characteristics of unpowered vertical diving motion of deep-sea autonomous underwater vehicle
Unpowered diving for deep-sea AUV(autonomous underwater vehicle)can effectively save energy.But it takes a long time to submerge in horizontal or small pitch attitudes,resulting in large horizontal drift.To improve the diving velocity and reduce the diving offset distance,the unpowered vertical diving motion of AUV was studied.To obtain the AUV motion equation using quaternions instead of Euler angles and incorporating ocean currents and buoyancy mathematic-al models,the motion simulation method of vertical diving for AUV is established though the Simulink simulation module.It solves the singularity problem of attitude angle solution caused by vertical diving.By setting different simulation conditions,the effects of negative buoyancy,distance between the center of gravity and the center of buoyancy,rudder angle,initial pitch angle,and environmental disturbance on the AUV vertical diving motion are obtained.The results show that the AUV can achieve a higher diving velocity and reduce the horizontal drift distance by using the vertical diving method;ocean cur-rent disturbance is the main cause of horizontal drift during vertical diving motion;when diving at a depth of 6 000 m,the disturbance of buoyancy changes results in the terminal diving velocity decreasing by 30%and the diving time increasing by 21%.