Bian Xin-qian

AUV local path planning based on virtual potential field

We build a local path planning algorithm using virtual force for free local minimum. Potential field is used as a basic platform for the path planning since it has the advantages of simplicity, real-time computation. However, there is one shortcoming in the potential field: it may cause local minimum whenever the curvature of the repulsive equipotential curve is less than the curvature of the attractive equipotential curve at the same configuration. To get rid of the local minimum in the presence of obstacles, we present a navigation algorithm, which integrates virtual force concept with a potential-field-based method to maneuver autonomous underwater vehicle (AUV) in unknown or unstructured environments. This study focuses on the free local minimum in potential-field based navigation. We mainly consider the potential-field method in conjunction with virtual force concept as the basis of our navigation algorithm. Simulation and experiments of our algorithm shows good performance and ability to overcome the local minimum problem associated with potential field methods.

Hybrid Control of Vision and Force for MEMS Assembly System

In this paper, we present a MEMS assembly system under hybrid control of vision and force feedback. The construction of a micro-vision system is introduced in detail and a new micro-force sensor was developed. The strategies of integrating force and vision feedback have been investigated experimentally and impact experimental results are presented. A task of pin in hole of Phi 0.1mm was completed. Using force feedback alone, at least twice as many searching steps are needed, while based on the hybrid control of micro-vision and micro-force feedback, one searching step is enough

Research on heading control of Air Cushion Vehicle

Air cushion vehicle (ACV) is a type of high performance watercraft. ACV can be propelled forward over the water, the ground and swale. It is widely used in both the civilian and military. Its operation is very different from general ships because of the structural particularity. We designed PID controller and neural net (NN) controller used for ACV heading control. Simulation results show that NN controller performs better than normal PID controller in heading control of ACV, especially when ACV is disturbed by wind.

New Model and Simulation of Condenser for Ship Nuclear Power Plant

A new reasonably perfect dynamic mathematic model has been established for condenser used in ship nuclear power plant according to its structural features and operating principle. The model has been solved by the Runge-Kutta method. And an analysis program has been developed for dynamic numerical simulation under steady operation condition, disturbance condition, and accident condition. The dynamic characteristics of condenser has been calculated and analyzed under several kinds of disturbances, and the results of calculation are in good agreement with the theoretical analysis.A new reasonably perfect dynamic mathematic model has been established for condenser used in ship nuclear power plant according to its structural features and operating principle. The model has been solved by the Runge-Kutta method. And an analysis program has been developed for dynamic numerical simulation under steady operation condition, disturbance condition, and accident condition. The dynamic characteristics of condenser has been calculated and analyzed under several kinds of disturbances, and the results of calculation are in good agreement with the theoretical analysis.

Simulation analysis of static and dynamic characteristics of once-through steam generator in concentric annuli tube

The once-through steam generator (OTSG) in concentric annuli tube is a new type of steam generator which applies double side to transfer heat. The heat flux between the water of centric tube, outside annuli tube and that of annulus channel is assumed to be equal, and then the steam generator’s model is built by lumped parameters with moving boundary. In the basis of the built model, static and dynamic characteristics are analyzed. The static characteristics are proved by experiment results in a 19-tube once-through steam generator of Babcock & Wilcox. The characteristics that the lengths of three regions (subcooled region, nucleate boiling region, superheat region) change with power can be explained by theory analysis. The dynamic characteristics accord with the heat and hydraulics and the results of analysis according to the mechanism.

3D track-keeping method for autonomous underwater vehicle

In this paper, 3D track-keeping control method for autonomous underwater vehicle (AUV) with and without the influence of ocean current is investigated. Because the system to be controlled is highly nonlinear and strong coupled, an approach is used to divide it into two subsystems. One is to control the heading and the track error on the horizontal plane. The other is to control the pitch and the track error on the vertical plane. The results of computer simulation show that the autopilot works properly, it can capture the current waypoint and turns to track the next path automatically.

Design and Implementation of Marine Environmental Information Observation System Based on UUV

A marine environmental information observation system based on UUV was designed and implemented to overcome the deficiency of marine environment observation mode through surface ship which is severely affected by the marine environment, unable to observe snugly and near sea bottom. This system comprises surface support subsystem and UUV subsystem, may navigate according to a pre-loaded mission plan and at the same time, can observe the planned marine environment information. The results of Qiandao lake experiments showed that the UUV system realized to observe the temperature, salinity, depth, current profile and submarine topography and geomorphology in predetermined water region. And the post processing results are consentaneous with the lake actual information. It indicates that the observational data are accurate, authentic and trustworthy.

Application of Improved Analytic Hierarchy Process to AUV's Decision-making

When autonomous underwater vehicle(AUV) is in subsea, it should quickly make a decision in order to acclimatize itself to the fateful change of situation. AUVs decision is restricted by many factors. Taking into account of main restrictions, the decision model of AUV is established and decision-making course based on improved analytic hierarchy process (IAHP) is explained too. The simulation and lake tests indicate that IAHP can efficiently solve the problem of AUVs decision-making under multi-restrictions.

Simulation study of plane motion of air cushion vehicle

This research is on horizontal plane motion equations of Air Cushion Vehicle (ACV) and its simulation. To investigate this, a lot of simulation study including ACV’s voyage and turning performance has been done. It was found that the voyage simulation results were accorded with ACV own characteristic and turning simulation results were accorded with USA ACV’s movement characteristic basically.

Fault diagnosing system of steam generator for nuclear power plant based on fuzzy neural networks

All kinds of reasons are analysed in theory and a fault repository combined with local expert experiences is established according to the structure and the operation characteristic of steam generator in this paper. At the same time, Kohonen algorithm is used for fault diagnoses system based on fuzzy neural networks. Fuzzy arithmetic is inducted into neural networks to solve uncertain diagnosis induced by uncertain knowledge. According to its self-association in the course of default diagnosis, the system is provided with non-supervise, self-organizing, self-learning, and has strong cluster ability and fast cluster velocity.