Integrated Vehicle Health Management Technology Research Articles

Digital Simulation and Identification of Faults with Neural Network Reasoners in Brushed Actuators Employed in an E-Brake System

The aerospace industry is constantly looking to adopt new technologies to increase the performance of the machines and procedures they employ. In recent years, the industry has tried to introduce more electric aircraft and integrated vehicle health management technologies to achieve various benefits, such as weight reduction, lower fuel consumption, and a decrease in unexpected failures. In this experiment, data obtained from the simulation model of an electric braking system employing a brushed DC motor is used to determine its health. More specifically, the data are used to identify faults, namely open circuit fault, intermittent open circuit, and jamming. The variation of characteristic parameters during normal working conditions and when faults are encountered are analysed qualitatively. The analysis is used to select the features that are ideal to be fed into the reasoner. The selected features are braking force, wheel slip, motor temperature, and motor angular displacement, as these parameters have very distinct profiles upon injection of each of the faults. Due to the availability of clean data, a data-driven approach is adopted for the development of the reasoner. In this work, a Long Short-Term Memory Neural Network time series classifier is proposed for the identification of faults. The performance of this classifier is then compared with two others—K Nearest Neighbour time series and Time Series Forest classifiers. The comparison of the reasoners is then carried out in terms of accuracy, precision, recall and F1-score.

Real-Time Maintenance Optimization Considering Health Monitoring and Additive Manufacturing

Prognostics Health Management (PHM) and Integrated Vehicle Health Management (IVHM) are extensive areas of research. Whereas a lot of work has been done in diagnostics and prognostics, economic viability is an important consideration. The availability of aircraft in the aerospace sector is a critical factor. Thus, cost and downtime are the main parameters to assess the impact of IVHM. Additionally, new repair technologies, such as additive manufacturing (AM), have the potential to become standard repair procedures, complementing IVHM, and its viability also has to be assessed. However, to accurately study the impact of these factors, the characteristics of aerospace maintenance have to be taken into account. Several approaches are followed in aircraft maintenance, depending on cost, downtime and aircraft availability constraints. For instance, some parts can be repaired on the ground and assembled again on the same aircraft, while single Line Replaceable Units (LRUs) need to be removed, replaced and later repaired in the workshop without affecting the availability of the aircraft. With the gradual introduction of IVHM, the viability of any new IVHM technology needs to be assessed.This paper describes an extensive cost and downtime model to take into account all these scenarios, including the impact of using different types of IVHM systems. The impact of IVHM and new repair technologies is discussed comparing maintenance cost and downtime of parts of LRUs and parts repaired when the aircraft is on the ground.Secondly, a real-time maintenance case study based on IVHM, a cost and downtime model and additive manufacturing is presented. This application allows the optimization of maintenance activities by updating the available resources and their corresponding cost and time, along with the actual prediction of the Remaining Useful Life (RUL) using a health monitoring system, instead of depending on historical component/sub-system failure probabilities.

Overview of Vehicle Integrated Propulsion Research (VIPR) Testing

Maintaining safe operation of an aircraft is a major emphasis of the NASA Aviation Safety Program [1]. An Integrated Vehicle Health Management (IVHM) system aims to maintain vehicle health through detection, diagnostics, state awareness, prognostics, and lastly, mitigation of detrimental situations for each of the vehicle subsystems and throughout the vehicle as a whole [2]. Major subsystems associated with a vehicle wide IVHM system are the airframe, avionics, and propulsion systems. Each subsystem has its own challenges associated with development of IVHM technologies. One particular challenging subsystem for vehicle health management is related to Propulsion Health Management (PHM). The engine is a complex system with a range of operating components whose failure can affect passenger safety. Reliable operation of these engines is critical for aircraft safety. The harsh environment conditions within an engine often present significant challenges for the integration and application of health management systems. In parallel, diagnostic systems often have to perform evaluations with limited sensor information, while evaluating a complex system whose components include gas path, turbomachinery, hydraulics, and other components. Demonstration of Propulsion Health Management technologies is critical for their commercial acceptance. A major aspect of ongoing NASA Propulsion Health Management work is demonstration of these maturing technologies on an operational engine in series of tests called Vehicle Integrated Propulsion Research, or VIPR. This paper gives a brief overview of the VIPR series of tests, the technologies involved in this testing, and how this approach is being used to advance the commercialization and acceptance of these technologies. VIPR is a means to test and evaluate emerging health management technologies on a commercial engine, incorporating new sensors directly on the engine, providing seeded fault scenarios, and evaluating advances in engine diagnostics. This step is critical in order for IVHM technologies to mature from lab work and simulation demonstrations needed for industry acceptance. This work is in partnership with the Air Force, which has provided access to two F117 high bypass turbofan engines and time on operational planes for the ground-based, on-board engine tests. In these tests, the research engines are instrumented to achieve NASA and partner goals and mounted on a C-17 aircraft, though it is important to note that the planes are grounded and do not take flight. A series of tests are planned with overall Vehicle Systems Safety Technologies (VSST) project objectives of testing health management sensors, sensor systems and algorithms on a high bypass turbofan engine under the following conditions: (1) Normal engine operations; (2) Seeded mechanical faults; (3) Seeded gas path faults; and (4) Accelerated engine life degradation through volcanic ash ingestion testing. The first VIPR test took place in December 2011 at NASA Dryden Flight Center/Edwards Air Force Base as an on-wing ground test on a heavily instrumented high bypass turbofan engine. This test featured: 1. Emission Sensor System: Investigation of the ability of of an array of chemical sensors to detect a simulated oil leak and measure changes in sensor response with changing engine conditions.2. Self Diagnostic Accelerometer feasibility test: Demonstrate operability of self-diagnostic accelerometer in aircraft engine environment3. Validate Gas Path Diagnostics: Test analytical model predictions of engine parameters in the presence of bleed valve faults (failed, full open; schedule bias) An unique feature of this VIPR series is an upcoming test, which includes the planned ingestion of volcanic ash into an engine on-board an aircraft. The primary objectives of this work are to determine the effect on the engine of several hours of exposure to low to moderate ash concentrations and to evaluate the capability of engine health management technologies for detecting these effects. Numerous observations and measurements of the engine’s performance and degradation will be made during the course of the experiment. While not intended to be sufficient for rigorous certification of engine performance when ash is ingested, the experiment should provide useful information to aircraft manufacturers, airline operators, and military and civil regulators in their efforts to evaluate the range of risks that ash hazards pose to aviation. A research team of U.S. Government agencies and engine manufacturers are involved in this VIPR testing. This government and industry partnership is not only crucial in enabling the tests, but is also a method by which various organizations can be involved in the demonstration and maturation of technologies, facilitating potential future acceptance. A conclusion of this paper is that partnerships between developers and users of new technologies are crucial towards enabling technology commercialization and acceptance. Not only does this type of work allow the ability to mature and evaluate the technologies in environments reflective of potential application, interaction with potential technology users can provide feedback on pathways towards technology improvements and possible implementation.

The effect of current military maintenance practices and regulations on the implementation of Integrated Vehicle Health Management technology

Health monitoring tools can be used to diagnose failures and estimate the remaining useful life of certain components, generating information that can be used to improve the management of logistics and maintenance activities in what is known as Integrated Vehicle Health Management (IVHM). The work presented here analyzes the effect of military practices and regulations on the benefits that can be expected from installing health monitoring tools on military aircraft. The findings on the impact of the military environment on short-term and medium-term goals of maintainers and operators are key to produce an accurate and reliable Cost-Benefit Analysis (CBA) for IVHM technology. The results of this work are based on information obtained through the use of a questionnaire to gather the knowledge of experts in the field and by studying military standards. Secondary benefits of implementing IVHM have been studied in detail to provide a guide of which are really relevant when working on a CBA and which can be ignored. The transition from current Condition Based Maintenance (CBM) practices included in military standards to the use of continuous health monitoring tools is also discussed. The effect of current outsourcing practices, such as availability contracts, is taken into account in the analysis of these issues.