: 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.

: Operation & support costs for military weapon systems accounted for approximately 3/5th of the $500B Department of Defense budget in 2006. In an effort to ensure readiness and decrease these costs for ground vehicle fleets, health monitoring technologies are being developed for Condition-Based Maintenance of individual vehicles within a fleet. Dynamics-based health monitoring is used in this work because vibrations are a passive source of response data, which are global functions of the mechanical loading and properties of the vehicle. A common way of detecting faults in mechanical equipment, such as the suspension and chassis of a ground vehicle, is to compare measured operational vibrations to a reference (or healthy) signature to detect anomalies. The main difficulty with this approach is that many vehicles are not equipped with sensors or the acquisition systems to acquire, process, and store data; therefore, to implement health monitoring, one must overcome the economic and technical barriers associated with equipping ground vehicles to continuously monitor the response. The research in this paper explores one approach that aims to overcome this difficulty. If a vehicle cannot be equipped with sensors, then an instrumented diagnostic cleat is proposed to measure the dynamic response of the vehicle as it traverses the cleat at a fixed speed. This approach could be effective because it eliminates the need for on-vehicle sensors, but provides measurements that indicate the condition of wheels/suspensions. A simple model of a HMMWV is used to simulate the approach. Experiments are also conducted using an instrumented cleat to demonstrate the feasibility of this approach.

A rubber cleat is instrumented with two triaxial accelerometers to measure the multi-directional response of the cleat due to the forces within the tire footprint of a ground vehicle. The cleat data is used to detect faults in the front and rear suspension in addition to the wheel tire despite variability in the data. This offboard diagnostic technique is proposed to enable condition-based maintenance.