Copyright (c) 2009 All rights reserved. http://works.bepress.com/cbirdson Recent documents in Charles Birdsong en-us Wed, 10 Jun 2009 11:43:49 PDT 3600 http://works.bepress.com/cbirdson/14 http://works.bepress.com/cbirdson/14 Mon, 08 Jun 2009 15:36:16 PDT Two electro-mechanical actuators are examined for a semi-active Helmholtz resonator acoustic device. The device is used to reflect narrow band noise back to the source in an acoustic duct. The controller and actuator are used to tune the system on-line allowing optimum performance over a range of operating conditions. Actuator. dynamics play an important role in the controller design and the operation of the device. Two variations of an electro-mechanical actuator are considered here. The first uses a dual voice coil speaker with local feedback compensation and the second uses the same speaker without the compensation. It is shown that both arrangements are effective but with competing advantages. The compensated actuator provides more control authority but adds considerable background noise while the uncompensated actuator provides less control authority but adds no background noise. The choice of actuator depends on the noise control objectives of the particular application. Charles Birdsong Conference Proceedings http://works.bepress.com/cbirdson/11 http://works.bepress.com/cbirdson/11 Thu, 04 Jun 2009 10:03:45 PDT A new USB powered portable 4-channel real time Dynamic Signal Analyzer and its automotive applications are described. The design and architecture lend themselves to real time NVH measurements and analysis in the field, in-vehicle or on production lines. Built-in signal conditioning provides for direct sensor power while the embedded DSP provides for signal processing on-board. Performance and implementation of FFT, digital filters and order analyses are presented. Charles Birdsong Conference Proceedings http://works.bepress.com/cbirdson/9 http://works.bepress.com/cbirdson/9 Thu, 04 Jun 2009 10:03:44 PDT In the past, control engineering was the exclusive province of computer and electrical engineers with advanced degrees and years of experience in low-level programming languages. Today, engineers and students alike can use Model-Based Design to rapidly design and implement real-time control systems without having to learn low-level programming. Used throughout the automotive and aerospace industries, Model-Based Design places a high-level system model at the center of development. This approach helps engineering students understand not only the basic physics of system components, but also the interaction between components and the behavior of the overall system. Charles Birdsong Articles http://works.bepress.com/cbirdson/10 http://works.bepress.com/cbirdson/10 Thu, 04 Jun 2009 10:03:44 PDT Many engineering systems create unwanted noise that can be reduced by the careful application of engineering noise controls. When this noise travels down tubes and pipes, a tuned resonator can be used to muffle noise escaping from the tube. The classical examples are automobile exhaust and ventilation system noise. In these cases where a narrow frequency band of noise exists, a traditional engineering control consists of adding a tuned Helmholtz resonator to reduce unwanted tonal noise by reflecting it back to the source (Temkin, 1981). As long as the frequency of the unwanted noise falls within the tuned resonator frequency range, the device is effective. However, if the frequency of the unwanted sound changes to a frequency that does not match the tuned resonator frequency, the device is no longer effective. Conventional resonators have fixed tuning and cannot effectively muffle tonal noise with time-varying frequency. Charles Birdsong Conference Proceedings http://works.bepress.com/cbirdson/13 http://works.bepress.com/cbirdson/13 Thu, 04 Jun 2009 10:03:41 PDT The future of vehicle safety will benefit greatly from precrash detection -the ability of a motor vehicle to predict the occurrence of an accident before it occurs. There are many different sensor technologies currently available for pre-crash detection. However no single sensor technology has demonstrated enough information gathering capability within the cost constraints of vehicle manufacturers to be used as a stand alone device. A proposed solution consists of combining information from multiple sensors in an intelligent computer algorithm to determine accurate precrash information. In this paper, a list of sensors currently available on motor vehicles and those that show promise for future development is presented. These sensors are then evaluated based on cost, information gathering capability and other factors. Cost sensitivity is lower in large commercial vehicles than sensitivity is lower in large commercial vehicles than in personal vehicles due to their higher initial cost and longer life span making them a good candidate for early adoption of such a system. This work forms the basis for ongoing research in developing an integrated object detection and avoidance precrash sensing system. John Carlin Conference Proceedings http://works.bepress.com/cbirdson/12 http://works.bepress.com/cbirdson/12 Thu, 04 Jun 2009 10:03:15 PDT Charles Birdsong Conference Proceedings http://works.bepress.com/cbirdson/8 http://works.bepress.com/cbirdson/8 Tue, 26 May 2009 11:13:12 PDT Automobile safety can be improved by anticipating a crash before it occurs and thereby providing additional time to deploy safety technologies. This requires an accurate, fast and robust pre-crash sensor that measures telemetry, discriminates between classes of objects over a range of conditions, and has sufficient range and area of coverage surrounding the vehicle. The sensor must be combined with an algorithm that integrates data to identify threat levels. No one sensor provides adequate information to meet these diverse and demanding requirements. However the requirements can be met with an optimal combination of multiple types of sensors. Previous work considered criteria for evaluating various sensors to find an optimal combination. This work presents test methods and results for selected sensors proposed for use in a pre-crash detection system. The test methods include static and dynamic telemetry testing to identify the range, accuracy, reliability and operating conditions for each sensor. Each sensor is evaluated for its ability to discriminate between classes of objects. The tests are applied to ultrasonic, laser range finder and radar sensors. These sensors were selected because they provide the maximum information, cover a broad range and region and are commercially viable in passenger vehicles. Charles Birdsong Conference Proceedings http://works.bepress.com/cbirdson/7 http://works.bepress.com/cbirdson/7 Wed, 13 May 2009 10:02:00 PDT This study improves the performance of a previously developed acoustic actuator in the presence of an acoustic duct system with strong pressure coupling. The speaker dynamics and the acoustic duct dynamics are first modeled separately. The two systems are then coupled, and the resulting system is modeled. A velocity sensor is developed and used in feedback compensation. The resulting speaker system has minimal magnitude and phase variation over a 20-200 Hz bandwidth. These conclusions are verified through experimental results. Charles Birdsong Articles http://works.bepress.com/cbirdson/6 http://works.bepress.com/cbirdson/6 Wed, 13 May 2009 10:01:55 PDT There are significant benefits of research for the involved undergraduate student. These include exposure to advanced topics, introduction to research methods, and direct interaction with faculty and other students. Faculty and institutions benefit as well by the increased interaction with students - fresh eyes in research projects, more energized research groups, and more engaged alumni. However, there are some challenges in designing a research program to work primarily with undergraduates. These include the students' lack of exposure to advanced topics, short tenure on the project, and potentially lower commitment to the results. There are a number of ways to address these concerns, however. Short student tenure and limited background can be offset by breaking up a long-term project into manageable short-term goals, allocating specific deliverables to each student, and implementing a rigorous data reporting and storage system. Motivation concerns can be handled through tying performance to student grades or to an external competition.This paper presents results of applying these techniques in a multi-disciplinary vehicle sensing research project involving sixteen undergraduates over a three-year period. Although individual student time on the project ranged from only three to twelve months, all students were able to contribute to the project. Student activities were grouped into individual and small group tasks, each with specific goals and timetables. Rigorous electronic documentation and data storage techniques were employed to enable new students to come up-to-speed quickly. A mix of course credits, supplemental pay, and an intercollegiate competition were used to maintain student motivation. Project successes include high student satisfaction, conference papers, a demonstration pre-crash sensing system, and participation in an international student competition. Peter Schuster Conference Proceedings http://works.bepress.com/cbirdson/5 http://works.bepress.com/cbirdson/5 Mon, 11 May 2009 10:55:01 PDT This paper describes a software simulator for pre-crash collision predictions. The simulator is a surrogate test bed for evaluating the performance of proposed pre-crash algorithms. It reads data from a file, transfers distance and angular position of a target to a test algorithm, and then records the algorithm's predictions. To illustrate the simulator functionality, a simplified test algorithm is also described. This algorithm predicts collision risks based on assumptions about the size and acceleration of a target object, and the turning and braking limits of the host vehicle. The test algorithm is shown to be effective for cases where both the vehicle and the target move along straight lines but less effective for curved paths. This result is typical of the difficulty in predicting the future position of another vehicle when its motion may change suddenly in the short time before a crash event. Dana Desrosiers Conference Proceedings