Diagnostic Health Monitoring System Development for Army Vehicle Reliability

摘要

Current maintenance schedules for ground vehicles are determined largely based on reliability predictions of a population of vehicles under anticipated operational loads. This approach leads to unnecessary maintenance and, in some cases, in-field failures depending on differences in the usage of individual vehicles. Condition-based maintenance is scheduled instead according to the condition of each vehicle to reduce the risk of failure and maintenance costs. However, on-board instrumentation for acquiring, processing, and storing operational data is expensive, and this data is also difficult to analyze due to variations in loading. An instrumented diagnostic cleat for diagnosing mechanical faults in ground vehicle wheel ends and suspensions is studied in this paper. The cleat excites the vehicle's dynamic response through an impulse delivered to the vehicle's front and back tires. The response of the instrumented segment of the cleat is then recorded while in contact with the vehicle's tires using accelerometers. The measured dynamic response is compared to a reference response, and anomalies that correspond to vehicle faults are then detected. This paper demonstrates that the measured response spectrum from the instrumented diagnostic cleat can be attributed to vehicle chassis modes of vibration in the frequency range below 10 Hz and natural frequencies in the free dynamic response of the cleat above 10 Hz. Tire and suspension faults are simulated in a high mobility multi-purpose wheeled vehicle and the faults are detected. Tire faults are simulated by decreasing the pressure within each tire below the manufacturer recommended level, whereas suspension faults are simulated by disconnecting each damper to mimic the effects of broken damper. The data indicates that the faults and locations of the faults are identified with 90% confidence in 7 out of 8 fault cases. Errors in the measurements are modeled to compensate for changes in vehicle speed.