| 1. |
- Armengol Llobet, J., et al.
(författare)
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Minimal Structurally Overdetermined Sets for Residual Generation: A Comparison of Alternative Approaches
- 2009
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Ingår i: <em>Proceedings of IFAC Safeprocess'09</em>. - Barcelona, Spain. - 9783902661463 ; , s. 1480-1485
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Konferensbidrag (refereegranskat)abstract
- The issue of residual generation using structural analysis has been studied by several authors. Structural analysis does not permit to generate the analytical expressions of residuals since the model of the system is abstracted by its structure. However, it determines the set of constraints from which residuals can be generated and it provides the computation sequence to be used. This paper presents and compares four recently proposed algorithms that solve this problem.
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| 2. |
- Ali, Mohammad, 1982, et al.
(författare)
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Automotive Threat Assessment Design for Combined Braking and Steering Maneuvers
- 2013
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Ingår i: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; PP:99, s. 1-1526
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Tidskriftsartikel (refereegranskat)abstract
- The active safety systems available on the passenger cars market today, automatically deploy automated safety interventions in situations where the driver is in need of assistance. In this paper, we consider the process of determining whether such interventions are needed. In particular, we design a threat assessment method which evaluates the risk that the vehicle will either leave the road or its maneuverability will be significantly reduced within a finite time horizon. The proposed threat assessment method accounts for combined braking and steering maneuvers, which results in a nonlinear dynamical vehicle behavior. We formulate the threat assessment problem as a nonconvex constraint satisfaction problem and implement an algorithm that solves it through interval-based consistency techniques. Experimental validation of the proposed approach indicates that constraint violation can be predicted, while avoiding the detection of false threats.
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| 3. |
- Armengol, Joaquim, et al.
(författare)
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SQualTrack: A Tool for Robust Fault Detection
- 2009
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Ingår i: IEEE Transactions on Systems, Man and Cybernetics Part B: Cybernetics. - 1083-4419. ; 39:2, s. 475-488
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Tidskriftsartikel (refereegranskat)abstract
- One of the techniques used to detect faults in dynamic systems is analytical redundancy. An important difficulty in applying this technique to real systems is dealing with the uncertainties associated with the system itself and with the measurements. In this paper, this uncertainty is taken into account by the use of intervals for the parameters of the model and for the measurements. The method that is proposed in this paper checks the consistencybetween the system’s behavior, obtained from the measurements, and the model’s behavior; if they are inconsistent, then there is a fault. The problem of detecting faults is stated as a quantified real constraint satisfaction problem, which can be solved using the modal interval analysis (MIA). MIA is used because it providespowerful tools to extend the calculations over real functions to intervals. To improve the results of the detection of the faults, the simultaneous use of several sliding time windows is proposed. The result of implementing this method is SemiQUALitative TRACKing (SQualTrack), a fault-detection tool that is robust in the sense that it does not generate false alarms, i.e., if there are false alarms, they indicate either that the interval model does not represent the system adequately or that the interval measurements do not represent the true values of the variables adequately. SQualTrack is currently being used to detect faults in real processes. Some of these applications using real data have been developed within the European project Advanced Decision Support System for Chemical/Petrochemical Manufacturing Processes and are also described in this paper.
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| 4. |
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| 5. |
- Gelso, Esteban, 1977
(författare)
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A proposal for the diagnosis of uncertain dynamic systems based on interval models
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The performance of a model-based diagnosis system could be affected by several uncertainty sources, such as,model errors,uncertainty in measurements, and disturbances. This uncertainty can be handled by mean of interval models.The aim of this thesis is to propose a methodology for fault detection, isolation and identification based on interval models. The methodology includes some algorithms to obtain in an automatic way the symbolic expression of the residual generators enhancing the structural isolability of the faults, in order to design the fault detection tests. These algorithms are based on the structural model of the system. The stages of fault detection, isolation, and identification are stated as constraint satisfaction problems in continuous domains and solved by means of interval based consistency techniques. The qualitative fault isolation is enhanced by a reasoning in which the signs of the symptoms are derived from analytical redundancy relations or bond graph models of the system. An initial and empirical analysis regarding the differences between interval-based and statistical-based techniques is presented in this thesis. The performance and efficiency of the contributions are illustrated through several application examples, covering different levels of complexity.
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| 6. |
- Gelso, Esteban, 1977, et al.
(författare)
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Consistent Threat Assessment in Rear-End Near-Crashes Using BTN and TTB Metrics, Road Information and Naturalistic Traffic Data
- 2017
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Ingår i: IEEE Intelligent Transportation Systems Magazine. - : Institute of Electrical and Electronics Engineers (IEEE). - 1939-1390 .- 1941-1197. ; 9:1, s. 74-89
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Tidskriftsartikel (refereegranskat)abstract
- Rear-end crashes are one of the most frequent types of traffic accidents. As a response, in order to assist the drivers, Advanced Driver Assistance Systems (ADAS) are being developed; particularly, Collision Avoidance Systems (CAS). Current CAS algorithms are commonly based on very simplified models of the preceding vehicle motion, under the assumptions of constant velocity or con-stant acceleration. This leads to several issues in the pre-diction of the lead vehicle behavior, and at the end, in the evaluation of the potential collision hazard. This paper identifies and addresses a hazard overestimation issue occurring in events related to rear-end (near) crashes that take place at traffic junctions. The issue was identified by analyzing 121 events found within data of 14640 driving hours collected in the framework of the Eu-ropean Field Operational Test on Active Safety Systems (euroFOT) project. Aiming to solve this issue, in this work it is proposed an enhanced model including road information to predict the lead vehicle braking behavior (deceleration pattern) of the CAS algorithms. Then, the hazard estimation is han-dled by a consistent event detection strategy, which uses simultaneously two metrics: the Time-to-Brake (TTB), and the Brake-Threat-Number (BTN). The result is the Consistent Threat Assessment for Longitudinal Motion Al-gorithm (CTALMA). The applicability of this algorithm is illustrated by an in-depth analysis of three test examples. Obtained results show a better assessment of the collision potential hazard and consistent event detection avoiding false alarms in all the cases.
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| 7. |
- Gelso, Esteban, 1977, et al.
(författare)
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Structural analysis extended with active fault isolation - methods and algorithms
- 2009
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Ingår i: 7th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes SAFEPROCESS.
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Konferensbidrag (refereegranskat)abstract
- Isolability of faults is a key issue in fault diagnosis whether the aim is maintenance or active fault-tolerant control. It is often encountered that while faults are detectable, they are only group-wise isolable from a usual diagnostic point of view. However, active injection of test signals on system inputs can considerably enhance fault isolability. This paper investigates this possibility of active fault isolation from a structural point of view. While such extension of the structural analysis approach was suggested earlier, algorithms and case studies were needed to explore this theory. The paper develops algorithms for investigation of the possibilities of activestructural isolation and it offers illustrative examples and a larger case study to explore the properties of active structural isolability ideas.
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| 8. |
- Gelso, Esteban, 1977, et al.
(författare)
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Threat assessment for driver assistance systems using interval-based techniques
- 2011
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Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - 1474-6670. - 9783902661937 ; 18:PART 1, s. 9782-9787
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Konferensbidrag (refereegranskat)abstract
- We present a threat assessment algorithm for driver assistance systems in which mathematical vehicle and driver models are used to explicitly account for the vehicle and driver behavior. For the application considered in this paper, requirements that the vehicle stays on the road while operating in a stable operating region are expressed as constraints on the vehicle states which need to be satisfied over a finite time horizon. The threat assessment problem is then formulated as a constraint satisfaction problem, solved through interval-based techniques considering bounded uncertainty in the measurements. Experimental results demonstrate the algorithms ability to detect unsafe operation in advance.
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| 9. |
- Gelso, Esteban, 1977, et al.
(författare)
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Towards a consistent threat assessment at traffic junctions using road information and naturalistic data: A test example
- 2015
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Ingår i: Proceedings of the 3rd International Symposium on Future Active Safety Technology Towards zero traffic accidents, 2015. ; , s. 477-482
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Konferensbidrag (refereegranskat)abstract
- This paper presents enhanced versions of two metrics: the Time-to-Brake (TTB) andthe Brake-Treat-Number (BTN), which are used as measures to describe the degree of beingcritical of traffic situations. The main idea is to include road information as input to obtain amore advanced prediction of the leading vehicle.The results, illustrated by an example using real data, show a better assessment of the collisionpotential hazard and no false alarms.
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| 10. |
- Janardhanan, Sachin, 1983, et al.
(författare)
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Motion control and power coordination of electric propulsion and braking distributed on multiple axles on heavy vehicles
- 2022
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Ingår i: 2022 IEEE Vehicle Power and Propulsion Conference, VPPC 2022 - Proceedings.
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Konferensbidrag (refereegranskat)abstract
- Instantaneous allocation of power in a distributed electric powertrain reduces losses by selective usage of actuators. Such an allocation also poses a challenge of coordinating power among actuators optimally. This study explores three different approaches of motion control and power coordination of electric machines and service brakes, using an instantaneous power allocation. These approaches based on control allocation framework, are further evaluated and compared for a given use case using simulations. The distinctive strength of the power loss minimisation approach, by using regressed data of power losses from electric machine models instantaneously, is highlighted. Additionally, it is also shown that the power loss minimisation approach resulted in the lowest energy loss in actuator power losses compared to the other approaches.
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