Xu Demin

On reverse navigation algorithm and its application to SINS gyro-compass in-movement alignment

Reverse navigation algorithms are deduced in detailed based on the classical strapdown inertial navigation system (SINS) updating algorithms. The scheme of SINS gyro-compass in-movement alignment is proposed and is divided into three steps, including level alignment with header uncertainty, coarse header alignment and gyro-compass alignment for header. On the assumption of navigation computer having large memory and powerful computing ability, the connection between in-movement alignment and vehicle position determining is established by reverse navigation algorithm. After the process of SINS gyro-compass in-movement alignment and saving sensorpsilas sample data to computer memory, reverse and normal dead reckoning algorithms are executed in succession to accomplish vehicle position updating. Finally, some vehicular tests prove that the proposed alignment algorithm in this paper is effective. In move base, the header alignment accuracy reaches 0.112deg(1sigma) and the position determining accuracy is about 0.1% by distance.

Design and experiment of automatic pilot for long-rang AUVs

The design of autonomous underwater vehicles is a complex work. In the past engineers designed AUV with concentrated-frame, this caught a lot of disadvantages, such as computerpsilas hard load, low capability of fault-tolerate, high failure rate and so on. Additionally the missions are more and more complex, AUVs need take more sensors to complete the mission, especially for long-rang AUVs. Traditional design method meets difficulties. This paper outlines a new method to design automatic pilot for long-range AUV. Distributed-frame structure is used to avoid the above shorts. In the hardware design CAN bus is adopted, this makes the communication between controller and executor more quickly. And in software design a real-time operation system called uC/OS is used, it solves the problem of time-delay. In the end the experimentation data shows that the system works well.

Cooperative Navigation Algorithm for Two Leaders GUUV

In this paper, we propose a moving long baseline algorithm based on double acoustic measurement for cooperative navigation of Group Unmanned Underwater Vehicle. Research on cooperative navigation of GUUV is an important topic to solve the navigation problem in long range and deep sea. We investigate the improvement in navigation accuracy. In the Leader-follow structure, the leader UUV is equipped with high precision navigation system, and the follow UUV is equipped with low precision navigation system. They all are equipped with acoustic device to measure relative location. Traditionally geometry triangulation method is used to calculate the position of follow UUV, the method may cause fault error solution. Double acoustic measurement method was designed, which fused the proprioceptive and exteroceptive sensors. The research results prove that the navigation accuracy has been improved effectively.

Stable adaptive control for nonlinear systems using neural networks

Stability analysis of neural-network-based nonlinear control has presented great difficulties. For a class of affine nonlinear systems with uncertainties, we employed nonlinear-parameter-neural-networks (NPNN) to approximate online the unknown nonlinearities, estimate online the NPNN approximation errors bound, and then succeeded in designing the control law and the adaptive laws of NPNNs weights and the NPNN approximation errors bound. The stability of the closed-loop is proved by using Lyapunov theory. Simulation results show that the controller we proposed exhibits excellent tracking performance.