Abstract
To achieve rapid and flexible vertical profile exploration of deep-sea hybrid structures, a multi-joint autonomous underwater vehicle (MJ-AUV) with orthogonal joints was designed. This paper focuses on the 3-dimensional (3D) modeling and attitude control of the designed vehicle. Considering the situation of gravity and buoyancy imbalance, a 3D model of the MJ-AUV was established according to Newton’s second law and torque balance principle. And then the numerical simulation was carried out to verify the credibility of the model. To solve the problems that the pitch and yaw attitude of the MJ-AUV are coupled and the disturbance is unknown, a linear quadratic regulator (LQR) decoupling control method based on a linear extended state observer (LESO) was proposed. The system was decoupled into pitch and yaw subsystems, treated the internal forces and external disturbances of each subsystem as total disturbances, and estimated the total disturbances with LESO. The control law was divided into two parts. The first part was the total disturbance compensator, while the second part was the linear state feedback controller. The simulation results show that the overshoot of the controlled system in the dynamic process is nearly 0 rad, reaching the design value very smoothly. Moreover, when the controlled system is in a stable state, the control precision is within 0.005%.
Highlights
Ocean exploration technology is one of the difficult problems in frontier science and engineering in the ocean field
The dynamic model of the multi-joint autonomous underwater vehicle (MJ-autonomous underwater vehicles (AUVs)) was built on the SIMULINK platform, According to Theorem 1, z is bounded stable
The results show that the estimated value of the total disturbance can follow the real value in real time and accurately, further proving the effectiveness of linear extended state observer (LESO) and making a great contribution to the control of the disturbance compensation
Summary
Ocean exploration technology is one of the difficult problems in frontier science and engineering in the ocean field. The MJ-AUV is a multi-rigid-body rootless system with high nonlinear and strong coupling characteristics, the kinematic and dynamic modeling of which is the basis of studying its motion behavior characteristics and control problems. Wu et al [16], Wang et al [17] and Kang et al [18] make improvements on the basis of the adaptive controller, which is verified in the field of motion control of AUVs. Zhang et al [19] present a sliding mode variable structure control algorithm, and simulation results show that this algorithm has advantages of high control accuracy and strong robustness. A novel AUV with orthogonal joints was proposed and designed for rapid and flexible vertical profile exploration of deep-sea hybrid structures, and the 3D motion model of the designed AUV was established according to Newton’s second law and the principle of moment balance.
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