JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

Error-CompensatingFive-SamplePhase-Shifting Algorithm Based on Phase-Shift Error Estimation

2001, 10(4): 337-341.

[Abstract](187)

Abstract:
A new error compensating five sample phase shifting algorithm which is insensitive to phase shift error is proposed to retrieve the phase distribution of a fringe pattern. It includes two steps. First, the linear phase shift error is estimated using four sample images. Then, the phase distribution is calculated with error corrected by using the phase shift error estimated in the first step. As the equations of error estimation and phase calculation are simple, this new algorithm is practical as well as effective. Computer simulations were carried out to verify the effectiveness of the algorithm. Results of two other well known error compensating algorithms are also presented, which show the new algorithm is the least sensitive to phase shift error.

Fast Digital Correlation Calculation Method in Extended Beacon Wavefront Detection

CHEN Ke, ZHAO Da zun

2001, 10(4): 342-348.

[Abstract](165)

Abstract:
On the basis of Hartmann Shack sensor imaging analysis, a new method is presented with which the wavefront slope can be obtained when the object is incoherent and extended. This method, which is demonstrated by both theoretical interpreting and computer simulation, explains how to measure the wavefront slope difference between two sub apertures through the determination of image displacements on detector plane. It includes a fast and accurate digital algorithm for detecting wavefront disturbance, which is much suitable for realization in such electrical hardwares as digital signal processors.

Theoretical Research on Electrorheological Isolator

ZHANG Shao hua, LI Mei yan

2001, 10(4): 349-355.

[Abstract](174)

Abstract:
A new type of isolator, the electrorheology (ER) isolator, is mainly described. Through theoretical analysis, a simplified physical model is established under some hypotheses and a series of motion equations are deduced. According to the transmissibility curve simulation under different electric field strengths, the main factors influencing ER isolator's working properties have been ascertained. Finally, it proves that ER isolator works well in both low and high frequency zones, it can decrease the force transmitted and enlarge the isolation frequency domain efficiently.

Application of Generalized Predictive Adaptive Control Algorithm in the Design of Missile Control System

WANG Zheng jie, LI Ji hong, ZHANG Tian qiao, RAO Si cheng

2001, 10(4): 356-363.

[Abstract](157)

Abstract:
To study the application of the generalized predictive adaptive control algorithm in missile control system, the algorithm is presented based on the recursive least square estimation, and a controller of the pitch channel of a missile is designed by using this algorithm. The simulations verify that the designed controller can meet the demands of the task well.

Model Reference Variable Structure Autopilot Design for Homing Missile

SONG Jian mei

2001, 10(4): 364-369.

[Abstract](156)

Abstract:
To design the control system for some homing missile so that the autopilot can transfer guidance command correctly and be robust to disturbances, such as the measurement noises and parameter variation caused by areodynamic floating. The model reference adaptive control was combined with the variable structure control to design a model reference variable structure (MRVS) control system whose control structure is simple and can be realized easily. The simulation results indicate that MRVS can complete the task of transferring guidance command and suppress the distrubances effectively.

Dynamic Simulation of Tracked Vehicle Using the DADS Software

GUO Jun, WANG Shen shen, LI Xiao lei

2001, 10(4): 370-375.

[Abstract](211)

Abstract:
The track model used in the dynamic analysis and design system software is investigated. A home made tank is taken as an example to illustrate the method for modeling an integral tracked vehicle and perform the dynamic simulation. The obtained results have demonstrated that the simulation method has the advantage of high efficiency, more convenience and more insight into the dynamical behavior of the system.

Multi-Layered Medium's General Green's Function Expression for Easily Calculating

LI Xiu ping, XU Xiao wen

2001, 10(4): 376-382.

[Abstract](150)

Abstract:
New general expressions of spectral Green's functions for scalar and vector potentials of vertical and horizontal electric as well as magnetic dipoles in a multi layered medium are presented and verified theoretically. In addition to their simplicity, the quasi static images of these expressions can be extracted without any difficulty. It is the most important that the spatial Green's functions in representation of Sommerfeld integrals can be easily obtained by using discrete complex image theory. Some numerical results for different kinds of multi layered medium presented in the end are used to verify the correctness of the general expressions.

Optimum Scheduling for the Chilled Water System of an Intelligent Building

GUO Qiao, FAN Xin jian

2001, 10(4): 383-388.

[Abstract](191)

Abstract:
The energy saving issue of chilled water system in an intelligent building is analyzed from the systematic point of view, and an optimum scheduling scheme which can save energy of the system facilities and satisfy the constraints of the real time cold loads and system running is also proposed. It can make the minimum cost of the system by optimizing the number of running chillers, running parameters and the distribution of real time loads of running chillers. The improved genetic algorithm is used in the optimum scheduling scheme. The computation results show that the building energy consumption can be decreased by about 10%.

Experimental Comparison Between PID Control and Friction Compensation Control for a Class of Nonlinear System with Friction

PENG Xi wei, ZHANG San tong

2001, 10(4): 389-394.

[Abstract](158)

Abstract:
A point to? point positioning control of systems with highly nonlinear frictions is studied. In view of variable frictions caused by the changes of load torque, an experimental comparison was made between the valve? controlled hydraulic motor servo system with PID control and that with friction compensation control. Experimental results show that the gross steady errors are caused by frictions when the system is controlled by the conventional proportional control algorithm. Although the errors can be reduced by introducing the integral control, the limit cycle oscillation and the long setting time are caused. The positioning error for a constant load torque can be eliminated by using fixed friction compensation, but poor positioning accuracy is caused by the same fixed friction compensation when the load torques varies greatly. The dynamic friction compensation based on the error and change in error measurements can significantly improve the position precision in a broad range of the changes of load torque.

Sub-Time-Optimal Control of Constrained Nonlinear Systems

ZHANG Juan, CHEN Jie, ZHANG Yu he

2001, 10(4): 395-401.

[Abstract](200)

Abstract:
To reduce the number of the level sets used in algorithm of constrained nonlinear systems via ellipsoidal techniques, according to the analysis of mathematics, searching algorithm is used for choosing the control input. Simulation shows that the number of level sets used for controlling is almost the same as that used in polytope techniques. Sub time optimal algorithm reduces the number of the level sets used in ellipsoidal techniques.

Asynchronous Data Fusion of Two Different Sensors

DAI Ya ping, WANG Jun zheng

2001, 10(4): 402-405.

[Abstract](159)

Abstract:
An algorithm is presented for fusion of tracks created by radar and IR sensor which have different dimensional measurement data. It's assumed that these sensors are asynchronous and the measurement data are transmitted to a central station at different rates. By means of the technique of time matching, two sets of asynchronous data are fused and then the filter is updated according to the fused information. The results show that the accuracy of the filter effect has been improved.

Computer Network Control System in Automatic Automobile Detection

GAO Yan, DOU Li hua, GAO Qi, ZHOU Ning

2001, 10(4): 406-411.

[Abstract](179)

Abstract:
An automobile test controlling and managing system with computer network is introduced. The architecture of the local network, hardware structure, software structure, design of the test process, and error tolerating redundant design in work position substituting are presented. At last, the pivotal questions solved are discussed. With an advanced structure, this system is multi functional and flexible. Furthermore, advanced computer technology is adopted to improve its technical degree.

Object-Oriented Modeling for Product Developing Process and It's Management System

XIANG Fei, NING Ru xin, YAO Jun

2001, 10(4): 412-417.

[Abstract](165)

Abstract:
To resolve the technical difficulty of managing the product developing process, an object model for product developing process is provided by using the object oriented methodology. In this model, the constituent objects including activity, transition, data, participant, application tool and resource as well as the relations between them are identified and discussed in detail. According to this model, a function framework of the process managing system is also proposed. Based on the object model and the function framework, product developing process and product information flow can be efficiently managed and controlled. As a result, costly errors and duplicate efforts are avoided in the product developing process, which is useful for shortening development cycle and improving product quality.

Application of Morphological Filter in Rosette Scanning Sub-Imaging System

ZOU Li jian, WANG Qian qian, LIU Jing hai

2001, 10(4): 418-422.

[Abstract](184)

Abstract:
To restore the sub image in a rosette scanning system and provide target recognition system with a low distorted image, the sub image is processed with morphological filters. Morphological filter can process rosette scanning sub images more effectively. It can restore the original area and shape of an object effectively, and keep the energy information of the object. To process sub images got by a rosette scanning system, morphological filter is more effective than traditional low pass filter.

Integrated Method of Recognizing Huge Target

WANG Wen hui

2001, 10(4): 423-428.

[Abstract](156)

Abstract:
An integrated novel method of recognizing huge target is described that combines some relatively mature image processing techniques such as edge detection, thresholding, morphology, image segmentation and so forth. After thresholding the edge image obtained by using Sobel operator, erosion is firstly used to reduce noise and extrusive pixels; then dilation is used to expand some separated pixels into various regions, after that the image segmentation technique is utilized to distinguish the target region with a criterion. The location of the target is also offered. Each technique adopted herein seems not complicated at all, the experimental results demonstrate the efficiency of the combination of these techniques. It is its high computational speed and remarkable robustness resulting from its simplicity that make the method promise to be applied in practical problems requiring real time processing.

Theory and Implementation of Distributed Visual Simulation

XU Chang wei, HOU Chao zhen

2001, 10(4): 429-435.

[Abstract](160)

Abstract:
The development process as well as the core theory of distributed interactive simulation and high level architecture are discussed, and combined with graphics features, a system of real time distributed visual simulation is established. Based on computer network, simulation platform is built by installing related software and modeling object, and the interactive functions are extended by programming. A set of solutions for building a distributed visual simulation system that include both hardware and software are put forward, and a practical instance is also provided. The whole building process can be summarized into two steps that are scheme consideration and system realization.

On-Board Data Acquisition System for Automatic Shift System of Vehicle

XI Jun qiang, CHEN Hui yan, DING Hua rong, DOU Jian ge

2001, 10(4): 436-442.

[Abstract](165)

Abstract:
Data acquisition, analysis and calibrating system affiliated with the vehicle is developed for the research on the automatic shift system (ASS). Considering the vehicle's hard environment such as vibration, high and low temperature, electromagnetic disturbance and so on, the most suitable project is selected. PC104 transfers data with ECU by serial communication and a solid state disk is used as a FLASH ROM. Some techniques including frequency division of data is adopted in the software design in order to ensure the sampling frequency. The analysis and debug software is also contrived according to the characteristic of the ASS. The system plays an important role in the development of the ASS because of the good reliability and practicability in the application.

Numerical Calculation for the Aero-Stab Seeker's Misalignment Angle

LEI Juan mian, MIAO Rui sheng, WU Jia sheng, JU Xian ming

2001, 10(4): 443-448.

[Abstract](189)

Abstract:
Numerical method based on three? dimension Navier Stokes equations are applied to study the aero? stab (aerodynamically stabilized) seeker's misalignment angle of laser guided bombs. A series of calculated misalignment angles varying with Ma and α were obtained, which are in good agreement with experimental data. The numerical results show that the misalignment angle is caused by the asymmetric aerodynamic disturbance of the bomb's forebody to the aero? stab seeker.

2001 Vol. 10, No. 4