A new version of a field-deployable real-time laser-based detection system has been developed using new techniques of electronics and optics. The laser-based non-intrusive 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. A new version field prototype of a detection system for real-time measurement of delineations of moving vehicles for highway testing has been developed based on our previous research on the laboratory prototype of the system. The new version utilizes new techniques in electronics, optics and software. The testing results show that the new system can obtain the accuracy of measurement necessary to distinguish moving vehicles on the highway. It is an important step to approach the final goal of this project, described in the last report as developing a roadway detection system that can be used to gather reliable travel time data non-intrusively. The new system quantitatively proved that the principle of measurement is feasible, instead of qualitatively as did the last version system. Several tests have been done with the field prototype system on the highway. The software for real-time data acquisition, data processing and graphical user interface has been developed in the Windows NT system with RTX real-time extension. In the software, the speed, acceleration, and length of a detected vehicle can be calculated and displayed simultaneously. This document describes the design and implementation of each functional component and software of the new field prototype system. The measurement and calculation of laser power has been performed to ensure that the system is safe to expose to the public during field tests and future operation on the highway.

Over the past year we have researched the development of a network-based real-time laser-based nonintrusive field-deployable detection for the delineation of moving vehicles. The primary goal of this project is to develop a roadway detection system that can be used to gather reliable travel time data non-intrusively. A powerful Rabbit 3200, instead of multi-microchips, is used to control digitally controlled potentiometers (DCP), which adjust the gain of the sensors' signals. Utilizing digitally controlled potentiometers allow for quick and easy adjustment on the highway with only the need of pushing a button. The adjustment, which used to take half or an hour, now only takes several seconds. The Rabbit 3200 is also used as a data sender to a computer through the Ethernet. The rabbit digital input ports are triggered to collect the signals by an interrupt pulse from a PWM signal, which also acts as the laser source trigger. The Rabbit 3200 will then pack all of the data into TCP packages and send them to a remote computer over a network. The Rabbit 3200 is also able to filter noise after having finished the task of adjustment. The software of the system has been modified for 8 channels. Compared with the previous 4 channel code, the new system is able to obtain more information on vehicles, including the profile of a passing vehicle. In order to improve the precision of the system, we improved the mechanical design, optical design and electric circuit design. We also use an interrupt to sample signals instead of a fixed sampling interval strategy. This method ensures every signal generated by the APD will be captured by the Rabbit 3200. The laser sources are pulsed at 10 kHz and the sampling rate of the Rabbit 3200 is synchronized to the 10 kHz laser pulse. This report describes the design and implementation of each functional component of the field-deployable system, the configuration of the field detection system, software design and implementation, and a signal calibration method to obtain higher system precision. It also demonstrates four different ways to test the field-deployable system and the results from each way of testing for future improvement.

We have developed a field prototype of a laser-based non-intrusive detection system for real-time measurement of delineations of moving vehicles for highway testing, based on our previous research on the laboratory prototype of the system. The primary goal of this project is to develop a roadway detection system that can be used to gather reliable travel time data non-intrusively. The 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 speed of both the front and rear of a vehicle is 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. We have built a field prototype detection system which is used not only to proof the concept and algorithm of the detection system, but also to test the system in the real traffic environment. Several tests have been done with the field prototype system on the highway, and the test results further verified that the principle of our detection system is technically sound and indicated that the algorithm implemented in the software works in most cases. The software for the real-time data acquisition, data processing and graphic user interface has been developed in a real-time operating system. In the software, the speed, acceleration, and length of a detected vehicle can be calculated and displayed simultaneously. This document describes the design and implementation of each functional component and software of the field prototype system. The measurement and calculation of laser power has been performed to ensure that the system is safe to expose to public during the field tests and future operation on the highway.