Abstract

Audio speakers are commonly used as acoustic actuators for noise control applications. Recent developments in the use of compensated dual-coil speakers have improved the performance of these acoustic actuators. However, the performance of these speakers depends on the application. When they are applied in systems with strong coupling between the plant and the actuator, the velocity sensor used in previous work must be improved.This study considers the application of a compensated speaker as an actuator. An acoustic duct is used an as example of a plant that exhibits strong dynamic pressure interaction with the actuator. 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 feed-back compensation. The resulting speaker system behaves as an ideal actuator with minimal magnitude and phase variation over a 0 -200 Hz bandwidth. These conclusions are verified through experimental results.This study is important in the overall area of acoustic actuators and active noise control. The actuator developed here will significantly aid in the goal of active noise control in an acoustic duct.

After ten years in body design and automotive safety at Ford Motor Company he joined the Mechanical Engineering department at Cal Poly. He teaches mechanics, design, stress analysis, and finite element analysis courses and serves as co-advisor to the student SAE chapter. Charles Birdsong, California Polytechnic State University Charles Birdsong has expertise in vibrations, controls, signal processing, instrumentation, real-time control, active noise control, and dynamic system modeling. He received his BSME at Cal Poly San Luis Obispo, MS and Ph.D. at Michigan State University where he worked on active noise control applications for the automotive industry. He has worked in the vibration test and measurement industry helping to drive new technologies to market and working with industry to meet their emerging needs. He is currently an Assistant Professor at Cal Poly in the Department of Mechanical Engineering teaching dynamics, vibrations and controls and is involved in several undergraduate and master's level multidisciplinary projects.

No abstract

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.