Wings Changing System Design And Flight Performance Research Of Hybrid Underwater Gliders With Controllable Wings

As carrying platforms for sensors, hybrid underwater gliders play an important part in ocean monitoring. Diverse monitoring tasks require better flight performance than usual. Flight efficiency, stability and maneuverability are three important flight performance. The importance of each performance will change at different conditions. For example, flight efficiency and stability are key performance during long endurance motion. However, maneuverability becomes key performance when gliders face obstacles, at which condition they should change direction. Current underwater gliders with fixed wings can't achieve all these performance in one flight mission, leading to weak self-adaptation ability. In order to improve the self-adaptation ability, hybrid underwater gliders with controllable wings are presented. Flight performance at various conditions can be improved by changing the aspect ratio, sweep angle and incidence angle. The research contents of the paper are as follows:Wings changing system of hybrid underwater gliders with controllable wings is developed. Independent wings changing cabin is integrated into Petrel?. Wings changing mechanism is designed to control separate wings. Combine planar five bar mechanism and planar double parallelogram mechanism together, the output bar's translation motion with two degree of freedom is achieved. Compression and sealing design of driving motors are conducted. Main parts of wings changing system are described in detail.Kinematics and dynamics analysis and simulation are conducted. Rotation vector algorithm is used to establish kinematics forward models of transmission mechanism. Simulation is conducted to analyze the working space and get the relation between driving motors and separate wings. The variation range of aspect ratio is 6 to 8, the variation range of sweep and incidence angle is 0° to 60° and 0° to 30°. Inputs of driving motors are obtained by inverse solutions. Simulation is carried out to obtain the input by giving the output in advance. Based on multi-body dynamics theory, models of transmission system are established. Torque of driving motors is obtained through dynamics' simulation, which can provide basis for motors selection.Based on multi-body dynamics theory, hybrid underwater gliders with controllable wings can be seen as multi-body system including six bodies. Kinematics and dynamics models of multi-body system are established. Forces of underwater gliders, which include gravity, buoyancy, thrust of propeller, inertial fluid force, viscous fluid force and the torques generated by relevant forces are analyzed in detail.Evaluation index of flight performance is analyzed. Space motion simulation of underwater gliders is conducted through fourth-order Runge-kutta of variable step. Wings' shape and attitude are chosen according to motion modes such as steady glide motion, space spiral motion and horizontal thrust motion. Lake trials are conducted according to simulation order in front of Danjiangkou Dam in July, 2014. The results of trials are consistent with the simulation, indicating that hybrid underwater gliders with controllable wings have better flight performance.