Zhaoqing Wang

Development and field test of a laser-based nonintrusive detection system for identification of vehicles on the highway

A real-time laser-based nonintrusive detection system has been developed for the measurement of true travel time of vehicles on the highway. The detection system uses a laser line that is projected onto the ground as a probe. The reflected light is collected and focused into a photodiode array by an optical system. Vehicle presence is detected based on the absence of reflected laser light. By placing two identical laser/sensor pairs at a known distance apart, the speeds of both the front and rear of a vehicle are measured based on the times when each sensor is triggered. The length of each vehicle is determined by using these speed measurements and the residence time of the vehicle under each sensor. Using real-time software, the speed, acceleration, and length of a detected vehicle can be calculated and displayed simultaneously. A new prototype system has been tested on the highway with different types of vehicles and scenarios, and the results are presented here. The tests have also been carried out for different weather conditions and road materials. The results indicate that the laser system operates well under real highway conditions.

Portable C/C++ code for portable XML data

Ch XML packages integrate an embeddable C-compatible interpreter with XML C/C++ toolkits giving developers the option of using portable C/C++ scripts to process portable XML data. XML is changing the world of information sharing and exchange by letting users clearly define their data and documents for specific tasks, such as electronic data interchange, content management, or publishing. XML uses context encapsulation to separate content from presentation and to support a hierarchical structure among data from various sources. XML data is reusable, easily derivable, and reconfigurable. However, XML-based applications need a programming technology to perform processing-related tasks such as parsing, generating, manipulating, and validating the data. Application developers commonly use toolkits based on C/C++, such as Gnomes XML C parser and toolkit, Oracles XML developers Kit for C/C++ (XDK), and Microsofts XML parser. These toolkits reflect the rich set of facilities, data types, operators, control structures, and runtime library functions that make C/C++ such a popular programming language. In fact, these tools, as well as the large number of skilled C/C++ programmers, often make C/C++ the preferred language for building portable systems

Performance Analysis for Design of a High-Precision Electronic Opto-Mechanical System for Vehicle Delineation Detection on Highway

We have developed a laser photodiode array based detection system that can non-intrusively detect delineations of vehicles on the highway. The U.S. Patent Office has recently approved a patent for this detection system. The system is built with low-cost off-the-shelf opto-mechanical components. The error sources from a system design point of view will be analyzed in this paper. Our study indicates that the frequency of pulsed laser diodes, computer-sampling rates, deviations in the angle of laser light and imperfectly matched detection points for sensor pairs are the main sources of error in the detection system.

Digitally Controlled Optimal Self-Calibration for a Laser-Photodiode Array Based Vehicle Detection System

The Laser-photodiode Based vehicle Detection System (LBDS) is an advanced vehicle detector. Its detection principle is based on projecting laser beams to the road and receiving the echo laser. When the operation environment such as the road surface condition, the weather and the daylight changes, which is likely to happen over the long-term lifespan of the LBDS, the LBDS may require recalibration. To solve this problem, a digitally-controlled optimal self-calibration method for LBDS is presented in the paper. With the calibration, the LBDS has the ability to operate reliably in a wide range of applications, and has the ability to provide correct and accurate detection information over the long term. The field test results of the LBDS using the proposed self-calibration method confirm the effectiveness of the self-calibration method.Copyright

Real-Time Architecture for an Electro-Mech-Optical System for Detection of Vehicles on Highway

A real-time architecture for a highway vehicle detection system is presented in the article. The Laser Based Detection System (LBDS), focused on helping the Intelligent Transportation System (ITS), measures a key quantitative parameter of vehicles moving across a link of highway, namely, travel time. Travel time is based upon the identifying and reidentifying vehicles at various points on the highway. This article provides a method to collect real-time signals from an active laser source in the LBDS and calculate vehicle parameters using a standard computer. A method of message exchange between a real-time kernel process, for real-time data acquisition, and a user space process, for computing and displaying, is given under the RTLinux environment. Experimental results from field tests have shown that the application of the real-time architecture to the LBDS provides speeds deterministically.Copyright

Noise rejection using variable-height timing-window technique for pulse signals with variable S/N ratio

This paper proposes a novel technique, known as the variable-height timing window (TW), for rejecting noise in an active source detection system. The basic principle of a TW and a methodology of using a microprocessor to dynamically adjust the height of the TW are presented. This variable-height TW technique has been applied to a laser-based detection system (LBDS) for detecting vehicle information on highways. Field-test results of the LBDS showed that the adaptive nature of the proposed TW approach can effectively reject various types of noise under different environmental conditions. This variable-height TW technique can also be used to remove out-of-window noise and suppress the effect of in-window noise in various field environments in which the signal/noise (S/N) ratio is variable.

Interpretive Real-Time Linux Interface and Its Applications

For time deterministic control, manufacturers and system designers of computer controlled machinery use real-time based systems to satisfy stringent requirements. Standard real-time systems contain built in kernel modules and often some type of user interface written in C. With a large multidimensional system spanning many smaller objective systems, it is hard for specialists to access real-time controlled objects on the spot. Making modifications to the user interface may require a slew of compilation and linking. This article presents an Interpretive Real-Time Linux Interface, which seamlessly integrates C/C++ applications using a C/C++ interpreter. Running the application interpretively makes the interface insensitive to user customization and product upgrading. An example of an insensitive interface is given in which a CGI web based user interface written in C has been implemented allowing users to control the frequency output of a speaker through a real-time Linux system from the web.Copyright