In recent years the commercial vehicle industry, specifically the heavy duty truck product line, has seen a rapid increase in the replacement of pure mechanical systems by electronic controlled systems. Engine, transmission, brakes, lighting, clusters, etc. are all monitored and/or controlled electronically. The adoption of electronic systems created a substantial change in the complexity of our products. Currently Diagnostic Trouble Codes (DTC) displayed on instrument clusters, in the majority of the cases, are no longer generated by a single sensor/component failure, instead these DTCs are triggered by a system monitor flag, result of a below average performance or a failure of an entire system. This new level of complexity makes it very difficult for the current diagnostic methods and tools, to identify what is causing the equipment to operate below ideal conditions.
This paper presents a fault-tolerant control (FTC) algorithm for four-wheel independently driven and steered (4WID/4WIS) electric vehicles. The Unscented Kalman Filter (UKF) algorithm is utilized in the fault detection and diagnosis (FDD) module so as to estimate the in-wheel motor parameters, which could diagnose parameters variations caused by in-wheel motor fault. A sliding mode controller (SMC) is able to compute the generalized forces/moments to follow the desired vehicle motion. By considering the tire adhesive limits, a reconfigurable control allocator optimally distributes the generalized forces/moment among healthy actuators so as to minimize the tire workloads once the actuator fault is detected. An actuator controller calculates the driving torques of the in-wheel motors and steering angles of the wheels in order to finally achieve the distributed tire forces. If one or more in-wheel motors lose efficacy, the FDD module diagnoses the actuator failures first.
Today, we are all strongly dependent on the correct functioning of technical systems. They fail, and we become vulnerable. Disruptions due to degradation or anomalous behavior can negatively impact safety, operations, and brand name, reducing the profitability of all elements of the value chain. This can be tolerated if the link between cause and effect is understood and remedied. Anomalous behavior, which indicates systems or subsystems not acting in accordance with design intent, is a much more serious problem. It includes unwanted system responses and faults whose root cause can’t be properly diagnosed, leading to costly, and sometimes unnecessary, component replacements. The title No Fault Found: The Search for the Root Cause was developed to propose solutions to this technical and business challenge, which has become less and less acceptable to the commercial aviation industry globally.
Time Domain Reflectometery (TDR) has been used for many years to find cable breaks and measure fluid levels in industrial processes. The technology uses picosecond level pulses and the associated reflection off of the fluid level surface in a time of flight measurement to determine fluid height. However, TDR signals have additional information that can be processed and exploited for IVHM applications. For example, when water collects in the fuel tank, TDR is capable of identifying and measuring the amount of water. This can allow for water sumps to be drained on condition instead of on a schedule. In addition, electromagnetic properties of the fluid can be determined, such as the dielectric constant and conductivity, which can be used to identify mis-fueling situations, contaminants in the fluid, and potentially other properties of fluid health.
Failure Root Cause Determination through the Aircraft Fault Messages Analysis Using Tree Augmented Naive Bayes and k-Nearest Neighbors
This paper presents a method to determine the root cause of an aircraft component failure by means of the aircraft fault messages history. The k-Nearest Neighbors (k-NN) and the Tree-Augmented naive Bayes (TAN) methods were used in order to classify the failure causes as a function of the fault messages (predictors). The contribution of this work is to show how well the fault messages of aircraft systems can classify specific components failure modes. The training set contained the messages history from a fleet and the root causes of a butterfly valve reported by the maintenance stations. A cross-validation was performed in order to check the loss function value and to compare both methods performance. It is possible to see that the use of just fault messages for the valve failure classification provides results that close to 2/3 and could be used for faster troubleshooting procedures.
This paper addresses the issue of detecting and isolating faults in complex networked systems. Complex Networked Systems typically contain multiple subsystems, components, and sensors interconnected through feedback control and thermal couplings. When a fault occurs in a component of a complex networked system, the effects of the fault may cause offnominal operations in other components due to fluctuations in their input signals. Health monitoring algorithms developed in literature typically result in false alarms during these scenarios since the data observed through sensor measurements are showing unhealthy characteristics even though the components are performing correctly given their offnominal input signals. This paper proposes a System Level Isolation and DEtection (SLIDE) algorithm that will detect and isolate faults occurring in multiple subsystems while reducing the computational complexity and minimizing false alarms.
The main function of the Environmental Control System (ECS) is to deliver thermal control and cabin pressurization of the air for the comfort and safety of crew members and the passengers on-board. The Heat Exchanger of the ECS is the critical component that ensures healthy system operation and maintains this key function. The heat exchanger mainly exhibits the failure known as fouling, which is the accumulation of clogging due to contamination. For safe and efficient operation of the ECS under the complex environments of aerospace systems, it is necessary to develop the capability to diagnose degradation of system components in the early phase of fault evolution. Periodic maintenance of these components without knowledge of their remaining useful life estimates causes significant financial expenses for the airliners and unnecessary interruption of aircraft operation.
Modern aircrafts, such as A380 or A350 for Airbus, are very well connected to ground stations through wireless communications. For maintenance and operations purpose, the aircraft is programmed to send regularly information such as flight reports based on the BITE messages (Built-In Test Equipments) or standard reports based on the value of physical parameters. Moreover, Airbus is capable of sending requests (called uplinks) to the aircraft to retrieve the value of different parameters in almost real-time. This ability, associated with adequate process, improves significantly the reaction time of the diagnostic and prognostic solutions that Airbus can provide to its customers. Traditionally Health Monitoring is considered useful when the Potential to Functional failure (P-F) interval is greater than one flight cycle.
Aircraft System Health Management (ASHM) is a UTC developed web application that provides access to Aircraft Condition Monitoring Function (ACMF) reports and Flight Deck Effects (FDE) records for B787 and A320 a/c. The tool was built with a flexible architecture to field a range of off-board diagnostics and prognostics modules designed to transform an abundance of data into actionable and timely knowledge about fleet health. This paper describes the ASHM system architecture and implementation with a focus on “lessons learned” in applying diagnostic and prognostics algorithms to available fleet data. Key topics include managing data quality issues, design for cross-enterprise collaboration and defining a workable approach to testing, validating and deploying prognostics and diagnostics models with various degrees of complexity. A case study is provided related to fluid leak detection within an environmental control subsystem.
Abstract A vehicle gearbox serves for torque and speed conversion with help of rotating elements. Therefore the gearbox experiences periodic excitation forces with a fundamental frequency following the rotation frequency. These excitation forces give rise to corresponding periodic response signals, i.e. signals having content at the fundamental (rotational) frequency and its harmonics. Order analysis is an analysis technique which is used to extract these harmonic orders from the response signals. This article intends to use the order tracking analysis for gearbox fault diagnosis under variable speed conditions to compare between healthy and faulty cases by using order extraction. Finally, determine maximum Root Mean Square (RMS) as severity index.
SAE J1939-73 Diagnostics Application Layer defines the SAE J1939 messages to accomplish diagnostic services and identifies the diagnostic connector to be used for the vehicle service tool interface. Diagnostic messages (DMs) provide the utility needed when the vehicle is being repaired. Diagnostic messages are also used during vehicle operation by the networked electronic control modules to allow them to report diagnostic information and self-compensate as appropriate, based on information received. Diagnostic messages include services such as periodically broadcasting active diagnostic trouble codes, identifying operator diagnostic lamp status, reading or clearing diagnostic trouble codes, reading or writing control module memory, providing a security function, stopping/starting message broadcasts, reporting diagnostic readiness, monitoring engine parametric data, etc.
The main purpose of this Recommended Practice is to verify that vehicles are capable of communicating a minimum subset of information, in accordance with the diagnostic test services specified in SAE J1979: E/E Diagnostic Test Modes, or the equivalent document ISO 15031-5: Communication Between Vehicle and External Equipment for Emissions-Related Diagnostics – Part 5: Emissions-related diagnostic services. Any software meeting these specifications will utilize the vehicle interface that is defined in SAE J2534, Recommended Practice for Pass-Thru Vehicle Programming.
Abstract Advancements in numerical weather prediction (NWP) models continue to enhance the quality of in-flight icing forecasts and diagnoses. When diagnosing current in-flight icing conditions, observational datasets are combined with NWP model output to form a more accurate representation of those conditions. Surface observations are heavily relied upon to identify cloud coverage and cloud base height above observing stations. One of the major challenges of using these point-based or otherwise limited observations of cloud properties is extending the influence of the observation to nearby points on the model grid. An alternate solution to the current method for incorporating these point-based observations into the in-flight icing diagnoses was developed. The basis for the new method is rooted in a concept borrowed from signal and image processing known as dithering.
This SAE Aerospace Information Report (AIR) is applicable to rotorcraft structural health monitoring (SHM) applications, both commercial and military, where end users are seeking guidance on the definition, development, integration, qualification, and certification of SHM technologies to achieve enhanced safety and reduced maintenance burden based on the lessons learned from existing Health and Usage Monitoring Systems (HUMS). While guidance on SHM business case analysis would be useful to the community, such guidance is beyond the scope of this AIR. For the purpose of this document, SHM is defined as “the process of acquiring and analyzing data from on-board sensors to evaluate the health of a structure.” The suite of on-board sensors could include any presently installed aircraft sensors as well as new sensors to be defined in the future. Interrogation of the sensors could be done onboard during flight or using ground support equipment.
Historically SAE has been concerned with nomenclature as an integral part of the standards development process. Guidelines for automotive nomenclature were written in 1916, were last revised in 1941, and were included in the SAE Handbook until 1962. The present diversity of groups working on nomenclature in the various ground vehicle committees led to the organization of the Nomenclature Advisory Committee under SAE Automotive Council.
This Technical Information Report defines the General Motors UART Serial Data Communications Bus, commonly referred to as GM UART. This document should be used in conjunction with SAE J2534-2 in order to fully implement GM UART in an SAE J2534 interface. SAE J2534-1 includes requirements for an interface that can be used to program certain emission-related Electronic Control Units (ECU) as required by U.S. regulations, and SAE J2534-2 defines enhanced functionality required to program additional ECUs not mandated by current U.S. regulations. The purpose of this document is to specify the requirements necessary to implement GM UART in an aftermarket SAE J2534 interface intended for use by independent automotive service facilities to program GM UART ECUs in General Motors vehicles.
Understanding the Effects of Fuel Type and Injection Conditions on Spray Evaporation Using Optical Diagnostics
Abstract Comparing with port-fuel-injection (PFI) engine, the fuel sprays in spark-ignition direct-injection (SIDI) engines play more important roles since they significantly influence the combustion stability, engine efficiency as well as emission formations. In order to design higher efficiency and cleaner engines, further research is needed to understand and optimize the fuel spray atomization and vaporization. This paper investigates the atomization and evaporation of n-pentane, gasoline and surrogate fuels sprays under realistic SIDI engine conditions. An optical diagnostic technique combining high-speed Mie scattering and Schlieren imaging has been applied to study the characteristics of liquid and vapor phases inside a constant volume chamber under various operating conditions. The effects of ambient temperature, fuel temperature, and fuel type on spray atomization and vaporization are analyzed by quantitative comparisons of spray characteristics.
Cylinder by cylinder indicated torque and combustion feature estimation based on engine instantaneous speed and one cylinder pressure through error similarity analysis
Abstract There is increasing demand for engine diagnostic and control with in-cylinder pressure signal. However, the application of cylinder pressure sensors are restricted by the high cost of the sensor. Another possible way for engine combustion state estimation is by processing of instantaneous crankshaft speed signal, but it is limited by the precision and complexity of the algorithm. It could be a solution by processing one cylinder pressure signal in combination with a crankshaft speed signal. The indicated torque could be estimated through engine speed processing and also from the measure cylinder pressure for the reference cylinder. Measurement results from experiments show that the indicated torque error traces of different cylinder are similar in shape. According to this assumption, the reference cylinder with cylinder pressure signal available can serve as both a parameter calibration information source and an error reduction measure.
Abstract Security access feature based on seed-key mechanism is widely used in automotive electronics, mainly for flashing ECU software, writing or reading specific parameter values and running diagnostic routines. There exist a number of techniques to decode the algorithm for key generation from a specific seed. Such techniques can put vehicle network at great risks due to an intruder flashing unauthorized version of ECU software, or changing internal parameters of ECU, or changing a VIN number. A lot more similar malicious attacks can be done by getting control over the ECUs. Attackers can exploit this vulnerability to alter the performance from the stock and affect the safety of the passengers. A novel and fool proof algorithm to protect the vehicle and ECU from such malicious attacks is explained in this paper. An advanced encryption technique is developed and tested in ECU to replace the current seed-key mechanisms for ECU security guarantying a secure operation of the vehicle.
Diagnostic Coverage Evaluation Method for Analog Circuits to Comply with Functional Safety Standards
Abstract The ISO 26262 is a functional safety standard for road vehicles. The standard requires manufacturers to conduct quantitative assessment of the diagnostic coverage (DC) of products. The DC is defined as the percentage of failure probability covered by safety mechanisms. However, DC evaluation methods for drift faults, in which the change in element values is not constant, have not been discussed. In this paper, we propose a DC evaluation method for analog circuits with drift faults. With this method, we first parameterize the effect of drift faults onto a bounded region then split the region into safe fault, hazardous detectable fault, and hazardous undetectable fault regions. We evaluate the classification rate distribution by the area ratios of these regions.
Cycle Resolved Combustion and Pre-Ignition Diagnostic Employing Ion Current in a PFI Boosted SI Engine
Abstract An ion current sensor is employed in a 4 cylinder production SI engine for combustion diagnosis during combustion process, knock, and low speed pre-ignition (LSPI) detection. The results show that the ion current peak value and ion current peak phase have strong correlation with the cylinder pressure and pressure peak phase respectively. The COV of ion current integral value is greater than the COV of IMEP at the same operating condition. Results show that the ion current signal is sensitive to different lambdas. Using ion current signal, the knock in any given cylinder can be detected. Importantly, the ion sensor successfully detected the low speed pre-ignition (LSPI) about more than 20 °CA before spark ignition.
Abstract Cavitation plays an important role in fuel injection systems. It alters the nozzle's internal flow structure and discharge coefficient, and also contributes to injector wear. Quantitatively measuring and mapping the cavitation vapor distribution in a fuel injector is difficult, as cavitation occurs on very short time and length scales. Optical measurements of transparent model nozzles can indicate the morphology of large-scale cavitation, but are generally limited by the substantial amount of scattering that occurs between vapor and liquid phases. These limitations can be overcome with x-ray diagnostics, as x-rays refract, scatter and absorb much more weakly from phase interfaces. Here, we present an overview of some recent developments in quantitative x-ray diagnostics for cavitating flows. Measurements were conducted at the Advanced Photon Source at Argonne National Laboratory, using a submerged plastic test nozzle.
The purpose of this SAE Aerospace Information Report (AIR) is to provide information that would be useful to potential users/operators and decision makers for evaluating and quantifying the benefits of an Engine Monitoring Systems (EMS) versus its cost of implementation. This document presents excerpts from reports developed to analyze "actual aircraft cost/benefits results". These are presented as follows: a. First, to outline the benefits and cost elements pertaining to EMS that may be used in performing a cost versus benefits analysis. b. Second, to present considerations for use in conducting the analysis. c. Third, to provide examples of analyses and results as they relate to the user/operator and decision-maker community. The document encompasses helicopters and fixed wing aircraft and distinguishes between civilian and military considerations.
SAE J1979 / ISO 15031-5 set includes the communication between the vehicle's OBD systems and test equipment implemented across vehicles within the scope of the legislated emissions-related OBD.
This document supersedes SAE J1962 200204, and is technically equivalent to ISO/DIS 15031-3: December 14, 2001. This document is intended to satisfy the requirements of an OBD connector as required by U.S. On-Board Diagnostic (OBD) regulations. The diagnostic connection specified in this document consists of two mating connectors, the vehicle connector and the external test equipment connector. This document specifies: a. The functional requirements for the vehicle connector. These functional requirements are separated into four principal areas: connector location/access, connector design, connector contact allocation, and electrical requirements for connector and related electrical circuits, b. The functional requirements for the external test equipment connector. These functional requirements are separated into three principal areas: connector design, connector contact allocation, and electrical requirements for connector and related electrical circuits.
The purpose of this document is to specify the functional requirements for a miniature connector to be used for health monitoring purposes on aircrafts (including harsh environment such as the powerplant). It is actually a family of miniature connectors that is specified in this document for various uses (e.g. pin counts) and environments. This specification will be used by the SAE connector committee to work on a dedicated connector standard.
Rotary SI/CI combustion engines: A thing of the future? The internal combustion engine enjoys widespread use as an inexpensive and reliable power conversion system. While piston engines date back 150 years, various alternative engine architectures and cycles have been considered. Aftertreatment comes with challenging diagnosis Diagnosing engine and aftertreatment systems is forcing design teams to look at new ways to diagnose problems over long vehicle lifetimes. Taking on NVH reduction techniques A look at the enhanced durability benefits obtained by changing the polymer composition, manufacturing methods, and design optimization of a powertrain mount for an off-highway vehicle.
SAE J1939-75 Generator Sets and Industrial Applications defines the set of data parameters (SPNs) and messages (PGNs) for information predominantly associated with monitoring and control generators and driven equipment in electric power generation and industrial applications. Applications using the SAE J1939-75 document may need to reference SAE J1939-71 for the SAE J1939 parameters and messages for monitoring and controlling the power units, e.g. engines and turbines, that power the generators and driven industrial equipment.
This Technical Information Report defines the diagnostic communication protocol TP1.6. This document should be used in conjunction with SAE J2534-2 in order to fully implement the communication protocol in an SAE J2534 interface. Some Volkswagen of America and Audi of America vehicles are equipped with ECU(s), in which a TP1.6 proprietary diagnostic communication protocol is implemented. The purpose of this document is to specify the requirements necessary to implement the communication protocol in an SAE J2534 interface. This Technical Information Report describes how a tester can be connected to a vehicle to perform diagnostics using the TP1.6 protocol. Details regarding ECU to ECU communication have been left out.
The purpose of this SAE Information Report is to specify the requirements necessary to fully define the Serial Data Communication Interface (SCI) used in the reprogramming of emission-related powertrain Electronic Control Units (ECU) in Fiat Chrysler Automobiles (FCA) vehicles. It is intended to satisfy new regulations proposed by the federal U.S. Environmental Protection Agency (EPA) and California Air Resource Board (CARB) regulatory agencies regarding "pass-thru programming" of all On-Board Diagnostic (OBD) compliant emission-related powertrain devices. These requirements are necessary to provide independent automotive service organizations and after-market scan tool suppliers the ability to reprogram emission-related powertrain ECUs for all manufacturers of automotive vehicles. Specifically, this document details the SCI physical layer and SCI data link layer requirements necessary to establish communications between a diagnostic tester and an ECU.