Control System Failure Research Articles

Flight control system failure modeling and verification based on SPIN

Abstract In the safety-critical systems domain, model-based safety analysis is an increasingly popular approach for failure assessment and verification, which utilizes model checking to verify whether there exist failures and their combinations in system that can lead to hazards. As a formal method, model checking explores the state space of a system model automatically to verify whether it meets safety requirements. Based on a highly-process description language called Promela, SPIN is an efficient model checker that can build system model to describe system's execution and perform random or interactive simulations to identify the failures hazards in system. Flight Control System (FCS) is one of the safety-critical systems in aircraft. This paper proposed a method that can be used to analyze through model checking whether there are potential failures and their combinations in FCS that can lead to hazards. The system model which is described by Promela is constructed in SPIN platform based on the control logic of FCS, and the subsystems in the FCS are abstracted for processes interacting with each other. The properties to be verified are defined by Linear Temporal Logic (LTL) formulas. The potential combinations of failures in FCS can be identified by analyzing the counter-examples produced by model checking, and the accident paths that lead to the hazard of FCS can be found as well. Results of SPIN model checker show that the proposed method can be effectively used to verify and find the combinations of failures that lead to the hazard in FCS.

How to effectively manage production facility low-temperature exposure risk

A significant risk with any oil and gas production facility is equipment exposure to low temperature fluids, which can lead to brittle fracture, loss of hydrocarbon containment and ignition, with potential consequences including multiple fatalities, major asset damage, production deferment and profound operator reputational harm. Due to the nature of the initiating low-temperature events, which often occur as a result of a sequence of control system, hardware or operational failures, these issues are not always adequately addressed in facility design and operation, which can lead to unacceptable and potentially unacknowledged asset risk exposure. This is especially true in a cost-constrained environment where economic and schedule pressures can drive a leaner approach whereby, for example, traditional design margins are challenged. Drawing on S2V Consulting’s extensive expertise in this area, this technical paper outlines examples of typical low-temperature exposure mechanisms and key facility risk areas. It highlights why there can be failures in mitigating these risks, both during initial facility design and throughout subsequent operating phase evolution, discusses analytical methods or tools and highlights potential mitigation measures. A structured evaluation process developed by S2V Consulting is presented that can be adopted to effectively safeguard facilities by ensuring these risks are identified, screened, prioritised and managed to ALARP (as low as reasonably practicable). Finally, case studies are presented to provide context to the issue and demonstrate the effective application of the evaluation process to several current Australian production facilities.

Development of methods for equivalent transformation of GERT networks for application in multi-version software

The usage of information and control systems in various fields of production and research requires a certain level of reliability in the functioning of these systems. One of the most promising and already positively proven methodologies to ensure high reliability and fault tolerance of software is multi-version designing. The greatest value this factor have in the areas where control system failure can result in significant financial and material losses, as well as harm to human health and life.

UAV aircraft model for control system failures analysis

In the paper, influence of control surface failures on UAV aircraft dynamics is investigated. A method for control loads determination for a nonlinear UAV aircraft model is presented. The model has been developed to analyse the influence of various control surface failures on aircraft controllability and to form the background for developing reconfiguration methods of flight control systems. The analysis of the control system failure impact on the aircraft dynamics and the ability of the control system to reconfiguration are presented.

Trajectory Specification for Terminal Air Traffic: Arrival Spacing

“Trajectory specification” is the explicit bounding and control of aircraft trajectories such that the position at each point in time is constrained to a precisely defined volume of space. The bounding space is defined by cross-track, along-track, and vertical tolerances relative to a reference trajectory that specifies position as a function of time. The tolerances are dynamic and are based on the aircraft navigation capabilities and the current traffic situation. A standard language will be developed to represent these specifications and to communicate them by datalink. Assuming conformance, trajectory specification can guarantee safe separation for an arbitrary period of time, even in the event of an air traffic control system or datalink failure; hence, it can help to achieve the high level of safety and reliability needed for air traffic control automation. As a more proactive form of air traffic control, it can also maximize airspace capacity and reduce the reliance on tactical backup systems during normal operation. It applies to both en route airspace and the terminal area around airports, but this paper focuses on arrival spacing in the terminal area and presents algorithms and software for achieving a specified delay of runway arrival time.

The potential for suppressing rail defect growth through tailoring rail thermo-mechanical properties

Thermal damage of rails can occur through brake lock-up, or traction control system failure to prevent wheel spin. In most cases the damage produced is shallow and takes the form of a “white etching layer”, usually thought to have a martensitic structure, formed as the steel is heated above its eutectoid temperature and then rapidly cooled as the wheel moves away. In many cases such layers are benign, but there is evidence of crack initiation at their interface with the sub-surface layers of the rail in “stud” defects. The metallurgical transformation during the formation of white etching layers leads to a volume change for the steel, leaving not only a transformed microstructure, but also locked-in stress. The influence of this additional locked-in stress on development of an initiated crack is studied in this paper, and the work extended to consider how alternative materials which react differently to the thermal input may offer a means to suppress crack development through locking in beneficial rather than problematic stresses.

English

The partial or complete failure of sensors and actuators used in twin rotor mimo system (TRMS) is considered as uncertainty, which may lead to control system failure resulting in severe damages. Hence there is a need to designed a controller which pe

An Overview of the Control System for Dose Delivery at the UCSF Dedicated Ocular Proton Beam

Since 1978, the University of California San Francisco (UCSF) Ocular Tumor Program has been using particle therapy for treating ocular patients with malignant as well as benign eye disease. Helium ion beams were used initially and were produced by two synchrotron-based systems: first by the 184-inch synchro-cyclotron and later by the Bevalac, at the Lawrence Berkeley National Laboratory (LBNL). Since 1994, protons, produced by a cyclotron-based system at the Crocker Nuclear Laboratory (CNL) Eye Treatment Facility (ETF), have been used for this purpose. The CNL cyclotron produces a 67.5 MeV beam, allowing for a uniquely homogeneous beam for eye treatment, without degradation of the beam or manipulation of the beam line. This paper describes, in detail, the control system for beam delivery, as implemented for measuring and delivering the radiation to ocular tumors at CNL. The control system allows for optimal delivery and rapid termination of the irradiation after the desired dose is achieved. In addition, several safeguard systems are discussed, as these are essential for such a system in the event of failure of software, electronics, or other hardware. The QA analysis shows that the total range of the proton beam is 30.7 ± 1.0 mm in water at iso-center. The beam distal penumbra (80% - 20%) is 1.1 mm for a range-modulated beam at a collimator to iso-center distance of 50 mm. Daily QA checks confirm that the range and modulation is within 0.1 mm. The beam flatness and symmetry in a 25 mm diameter beam are ±1% - 2%. Variation in the daily dosimetry system, as compared to standard dosimetry, is within ±3.5%, with a mean variation of 0.72(±1.9)% and 0.85(±2.3)% for segmented transmission ionization chambers IC1 (upstream) and IC2 (downstream), respectively. From May 1994 to the end of 2015, UCSF has treated 1838 proton ocular patients at the Davis ETF. During this period, no treatments were missed due to any cyclotron or control system failures. The overall performance, maintenance, and quality assurance of the cyclotron and the ocular control system have been excellent.

Automated Ongoing Commissioning via Building Control Systems

ABSTRACTIt is well known that commissioning of new buildings is a great way to save energy and money. Likewise, re-/retro-commissioning existing buildings is an extremely cost effective way to recapture those energy savings that have been lost over time due to changes and failures in the Building Control Systems (BCS). There should be a better way to continually maintain energy savings over time. A superior solution is to use the existing BCS.Most buildings of any size or complexity are designed with a BCS to handle the complexities of an HVAC system. Most of the complexities are present to reduce operating costs—otherwise, all the BCS needs to do is to maintain a comfortable working environment by controlling space temperatures, humidity and air quality. To reduce operating costs, the BCS performs all kinds of additional, somewhat complex operations, as listed below. Air handling unit (AHU) scheduling—Schedule the air handler off after business hours with higher or low space temperatures and return to op...

Self-organizing fuzzy failure diagnosis of aircraft sensors

A novel scheme for diagnosing sensor failures in a flight control system is presented. In the proposed scheme, a set of self-organizing fuzzy systems named as extended sequential adaptive fuzzy inference systems (ESAFISs) are applied as the online approximators for recognizing the sensor outputs. ESAFIS is an online learning fuzzy system with concurrent structure and parameter learning. The rules of the ESAFIS are added or deleted based on the input data without predefining them by trial and error. From an analysis of the residual signals between the estimated states and the measurements of the sensors, the failure diagnosis by determining the failure detection, identification and accommodation can be achieved. The efficiency of the proposed scheme is demonstrated by simulation examples where hard and soft failures in the angular rate gyros are successfully diagnosed.

Subcritical space nuclear system without most movable control systems

This paper describes the design and analysis of advanced space nuclear reactor (ASNR) whose design combines the advantages of radioisotope thermoelectric generator (RTG) and space nuclear reactor (SNR). As opposed to current SNRs designs, ASNR is a subcritical system driven by 232U–Be neutron source to generate thermal power continuously. Most movable control systems in the SNR design are removed. The detailed neutronic calculations by MCNPX (Monte Carlo N-Particle eXtended), including keff, flux, burn-up, loss-ratio of neutron source and immersion reactivity, show that ASNR has higher criticality safety and more compact structure to bear the risk of immersion accident compared with the past SNRs, and the new system can provide more thermal power than RTG. Furthermore, the neutron source efficiency is optimized to improve the utilization of 232U–Be neutron source with the improvement of criticality safety. Compared with the past designs of space nuclear power, ASNR could provide enough thermal power and avoid the occurrence of serious immersion accident in the case of total control system failure. ASNR has potential for future deep space missions.

A Fuzzy-Multiagent Service Restoration Scheme for Distribution System With Distributed Generation

This paper proposes a new multiagent control system (MACS) for service restoration in distribution systems with integrated distributed generation (DG) units. First, the MACS detects and locates faults, then decides the optimal reconfiguration of the network for restoring de-energized loads, and finally regulates the nodes voltages. Unintentional islanding operation of DG units is avoided and different postfault response modes of DG unit are addressed in the MACS design. The MACS has a hybrid centralizeddecentralized structure where agents are arranged in two layers with different responsibilities and communication capabilities. Agents at load buses in the first layer can only communicate directly with its next neighbor load agents on the same feeder and to its feeder agent, whereas the higher level agents in the second layer can communicate directly with each other. This MACS structure reduces the possibilities of control system failures for a moderate communication network infrastructure. Full dynamic simulation model for evaluating the MACS is implemented.

Gait and computerized dynamic posturography (CDP) aspects in early progressive supranuclear palsy (PSP) - a case report.

BACKGROUND: Posture and gait instability may cause of morbidity in individuals with progressive supranuclear palsy (PSP). OBJECTIVE: To quantitatively measure balance control by using computerized dynamic posturography (CDP) and to assess gait analysis in early PSP.CASE REPORT: She was evaluated for Berge balance scale, Functional Independence Measure (FIM) and postural stability using CDP device in early PSP with still able to walk or stand unassisted. Also, Gait analysis was conducted using an 8 M-camera Vicon 612 data capturing system set. Berge balance scale improved from 41/56 to 48/56. The score of FIM improved from 71/126 points to 95/126 points in early PSP. In CDP analysis, there was a decrease of composite equilibrium score (38 %). There was an increase of composite equilibrium score (59%) after three months of treatment. In gait analysis, there was no difference of gait parameters after three months of treatment in early PSP.CONCLUSIONS: Both CDP and gait analysis are important quantitative tools in the assessment of posture and gait instability as well as allow for early disclosure of the failure of the postural control system in early PSP.

Gait and Computerized Dynamic Posturography (CDP) Aspects in Early Progressive Supranuclear Palsy (PSP) - A Case Report

BACKGROUND: Posture and gait instability may cause of morbidity in individuals with progressive supranuclear palsy (PSP). OBJECTIVE: To quantitatively measure balance control by using computerized dynamic posturography (CDP) and to assess gait analysis in early PSP.CASE REPORT: She was evaluated for Berge balance scale, Functional Independence Measure (FIM) and postural stability using CDP device in early PSP with still able to walk or stand unassisted. Also, Gait analysis was conducted using an 8 M-camera Vicon 612 data capturing system set. Berge balance scale improved from 41/56 to 48/56. The score of FIM improved from 71/126 points to 95/126 points in early PSP. In CDP analysis, there was a decrease of composite equilibrium score (38 %). There was an increase of composite equilibrium score (59%) after three months of treatment. In gait analysis, there was no difference of gait parameters after three months of treatment in early PSP.CONCLUSIONS: Both CDP and gait analysis are important quantitative tools in the assessment of posture and gait instability as well as allow for early disclosure of the failure of the postural control system in early PSP.

On-line failure prediction in safety-critical systems

In safety-critical systems such as Air Traffic Control system, SCADA systems, Railways Control Systems, there has been a rapid transition from monolithic systems to highly modular ones, using off-the-shelf hardware and software applications possibly developed by different manufactures. This shift increased the probability that a fault occurring in an application propagates to others with the risk of a failure of the entire safety-critical system. This calls for new tools for the on-line detection of anomalous behaviors of the system, predicting thus a system failure before it happens, allowing the deployment of appropriate mitigation policies.The paper proposes a novel architecture, namely CASPER, for online failure prediction that has the distinctive features to be (i) black-box: no knowledge of applications internals and logic of the system is required (ii) non-intrusive: no status information of the components is used such as CPU or memory usage; The architecture has been implemented to predict failures in a real Air Traffic Control System. CASPER exhibits high degree of accuracy in predicting failures with low false positive rate. The experimental validation shows how operators are provided with predictions issued a few hundred of seconds before the occurrence of the failure.

Analysis of vortex-induced and stall-induced vibrations at standstill conditions using a free wake aerodynamic code

Vortex-induced and stall-induced vibrations of a 2D elastically mounted airfoil at high angles of attack in the vicinity of 90° are investigated using a vortex type model. Such conditions are encountered in parked or idling operation at extreme yaw angles provoked by control system failures. At very high angles of attack, massive flow separation takes place over the entire blade span, and vortex shedding evolves downstream of the blade giving rise to periodically varying loads at frequencies corresponding to the Strouhal number of the vortices shed in the wake. As a result, vortex-induced vibrations may occur when the shedding frequency matches the natural frequency of the blade. A vortex type model formulated on the basis of the ‘double wake’ concept is employed for the modelling of the stalled flow past a 2D airfoil. By tuning the core size of the vortex particles in the wake, the model predictions are successfully validated against averaged 2D measurements on a DU-96-W-180 airfoil at high angles of attack. In order to assess the energy fed to the airfoil by the aerodynamic loads, the behaviour under imposed sinusoidal edgewise motions is analysed for various oscillation frequencies and amplitudes. Moreover, stall-induced and vortex-induced vibrations of an elastically mounted airfoil section are assessed. The vortex model predicts higher aeroelastic damping as compared with that obtained using steady-state aerodynamics. Excessive combined vortex-induced and stall-induced edgewise vibrations are obtained beyond the wind speed of 30 m s−1. Copyright © 2014 John Wiley & Sons, Ltd.

Methods to Establish the Fault Tree of Substation Automation System Based on HAZOP

Because of it’s complexity of substation, once the control system failure will cause huge losses, according to the fault characteristics, established the HAZOP method combined with the method of fault tree model, and the substation and protection and control system as an example, the modeling process complete sample. This method can standardize and establish fault tree, provides a scientific, reasonable means to discover substation system inherent or potential risk factors.

Computerized Dynamic Posturography in Patients with Diabetic Peripheral Neuropathy and Visual Feedback-Based Balance Training Effects

BACKGROUND: Diabetic peripheral neuropathy (DPN) often has reduced stability during standing conditions.AIM: To compare balance control in diabetic patients and normal subjects using computerized dynamic posturography and to assess effect of visual feedback-based balance training in DPN.MATERIALS AND METHODS: A total of 57 patients of type 2 diabetes mellitus and 30 age-matched normal control subjects were recruited. The sensory organization test was done before and after the training program.RESULTS: There was a significant decrease of mean (± SD) of composite equilibrium score and somatosensory ratio score between subgroups of DPN and control healthy group (p < 0.05). There was a significant increase of mean (± SD) of composite equilibrium score and the somatosensory ratio score after treatment as compared to results before training (p < 0.05) in mild DPN. Moreover, there were a significant correlation between composite equilibrium score and disease duration before training in the severe DPN (r = 0.368, p < 0.05). CONCLUSIONS: Computerized dynamic posturography is an important quantitative tool in the assessment of posture instability and allows for early disclosure of the failure of the postural control system. Visual feedback-based balance training was shown to be a promising method for fall prevention among early diabetes mellitus with peripheral neuropathy.

Analysis and Design of Automatic Transmission’ Hydraulic System Based on Logic Analysis

Volkswagen AG4 Automatic transmission ,for example , was detailed analyzed by logical method from the shifting operation, interlocking of combining elements and failure protection. Shifting operation must first meet the shifting demand ,mangy oil line criss-cross in the automatic transmission hydraulic system circuit ,in a particular gear ,some components must to be meet bonding requirements interlock between them ,finally ,vehicle need a failure system to protect the oil line to prevent failures in order to travel to the failure of the automatic transmission electronic control system .By analyzing ,design principles and ideas of automatic transmission shift controlling hydraulic system were derived.

Loss functions and their applications in process safety assessment

Process deviations, along with failure of control systems and protection layers, result in safety and quality loss in plant operations. This article proposes an operational risk‐based warning system design methodology based on overall system loss. Loss functions (LFs) are used to define the relationship between process deviations and system loss. For this purpose, properties associated with quadratic LF and a set of inverted probability LFs are investigated and compared. The results suggest that LFs can be used in a novel way to assess operational stability and system safety. The proposed consequence assessment methodology using LFs is then incorporated into a risk‐based warning system design model to analyze warnings associated with process deviations. A simulated case study is presented to demonstrate potential application of the proposed methodology; the study examines the response to a temperature surge for a reactor system. © 2014 American Institute of Chemical Engineers Process Saf Prog 33: 285–291, 2014