| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- Mohan, Naveen, et al.
(författare)
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A Method towards the Systematic Architecting of Functionally Safe Automated Driving- Leveraging Diagnostic Specifications for FSC design
- 2017
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Ingår i: SAE technical paper series. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; 2017-March:March
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Tidskriftsartikel (refereegranskat)abstract
- With the advent of ISO 26262 there is an increased emphasis on top-down design in the automotive industry. While the standard delivers a best practice framework and a reference safety lifecycle, it lacks detailed requirements for its various constituent phases. The lack of guidance becomes especially evident for the reuse of legacy components and subsystems, the most common scenario in the cost-sensitive automotive domain, leaving vehicle architects and safety engineers to rely on experience without methodological support for their decisions. This poses particular challenges in the industry which is currently undergoing many significant changes due to new features like connectivity, servitization, electrification and automation. In this paper we focus on automated driving where multiple subsystems, both new and legacy, need to coordinate to realize a safety-critical function. This paper introduces a method to support consistent design of a work product required by ISO 26262, the Functional Safety Concept (FSC). The method arises from and addresses a need within the industry for architectural analysis, rationale management and reuse of legacy subsystems. The method makes use of an existing work product, the diagnostic specifications of a subsystem, to assist in performing a systematic assessment of the influence a human driver, in the design of the subsystem. The output of the method is a report with an abstraction level suitable for a vehicle architect, used as a basis for decisions related to the FSC such as generating a Preliminary Architecture (PA) and building up argumentation for verification of the FSC. The proposed method is tested in a safety-critical braking subsystem at one of the largest heavy vehicle manufacturers in Sweden, Scania C.V. AB. The results demonstrate the benefits of the method including (i) reuse of pre-existing work products, (ii) gathering requirements for automated driving functions while designing the PA and FSC, (iii) the parallelization of work across the organization on the basis of expertise, and (iv) the applicability of the method across all types of subsystems.
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| 3. |
- Mohan, Naveen, et al.
(författare)
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AD-eye : A co-simulation platform for early verification of functional safety concepts
- 2019
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Ingår i: SAE technical paper series. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; 2019-April:April
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Tidskriftsartikel (refereegranskat)abstract
- Automated Driving is revolutionizing many of the traditional ways of operation in the automotive industry. The impact on safety engineering of automotive functions is arguably one of the most important changes. There has been a need to re-think the impact of the partial or complete absence of the human driver (in terms of a supervisory entity) in not only newly developed functions but also in the qualification of the use of legacy functions in new contexts. The scope of the variety of scenarios that a vehicle may encounter even within a constrained Operational Design Domain, and the highly dynamic nature of Automated Driving, mean that new methods such as simulation can greatly aid the process of safety engineering. This paper discusses the need for early verification of the Functional Safety Concepts (FSCs), details the information typically available at this stage in the product lifecycle, and proposes a co-simulation platform named AD-EYE designed for exploiting the possibilities in an industrial context by evaluating design decisions and refining Functional Safety Requirements based on a reusable scenario database. Leveraging our prior experiences in developing FSCs for Automated Driving functions, and the preliminary implementation of co-simulation platform, we demonstrate the advantages and identify the limitations of using simulations for refinement and early FSC verification using examples of types of requirements that could benefit from our methodology.
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| 4. |
- Mohan, Naveen
(författare)
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Architecting Safe Automated Driving with Legacy Platforms
- 2018
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Modern vehicles have electrical architectures whose complexity grows year after year due to feature growth corresponding to customer expectations. The latest of the expectations, automation of the dynamic driving task however, is poised to bring about some of the largest changes seen so far. In one fell swoop, not only does required functionality for automated driving drastically increase the system complexity, it also removes the fall-back of the human driver who is usually relied upon to handle unanticipated failures after the fact. The need to architect thus requires a greater rigour than ever before, to maintain the level of safety that has been associated with the automotive industry.The work that is part of this thesis has been conducted, in close collaboration with our industrial partner Scania CV AB, within the Vinnova FFI funded project ARCHER. This thesis aims to provide a methodology for architecting during the concept phase of development, using industrial practices and principles including those from safety standards such as ISO 26262. The main contributions of the thesis are in two areas. The first area i.e. Part A contributes, (i) an analysis of the challenges of architecting automated driving, and serves as a motivation for the approach taken in the rest of this thesis, i.e. Part B where the contributions include, (ii) a definition of a viewpoint for functional safety according to the definitions of ISO 42010, (iii) a method to systematically extract information from legacy components and (iv) a process to use legacy information and architect in the presence of uncertainty to provide a work product, the Preliminary Architectural Assumptions (PAA), as required by ISO 26262. The contributions of Part B together comprise a methodology to architect the PAA. A significant challenge in working with the industry is finding the right fit between idealized principles and practical utility. The methodology in Part B has been judged fit for purpose by different parts of the organization at Scania and multiple case studies have been conducted to assess its usefulness in collaboration with senior architects. The methodology was found to be conducive in both, generating the PAA of a quality that was deemed suitable to the organization and, to find inadequacies in the architecture that had not been found earlier using the previous non-systematic methods. The benefits have led to a commissioning of a prototype tool to support the methodology that has begun to be used in projects related to automation at Scania. The methodology will be refined as the projects progress towards completion using the experiences gained.A further impact of the work is seen in two patent filings that have originated from work on the case studies in Part B. Emanating from needs discovered during the application of the methods, these filed patents (with no prior publications) outline the future directions of research into reference architectures augmented with safety policies, that are safe in the presence of detectable faults and failures. To aid verification of these ideas, work has begun on identifying critical scenarios and their elements in automated driving, and a flexible simulation platform is being designed and developed at KTH to test the chosen critical scenarios.
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| 5. |
- Mohan, Naveen, et al.
(författare)
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ATRIUM analysis with AD-EYE and RCV-E
- 2023
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Annan publikation (mjukvara/multimedium) (övrigt vetenskapligt/konstnärligt)abstract
- ATRIUM analysis with AD-EYE and RCV-E This repository contains code for the AD-EYE testbed for Automated Driving and Intelligent Transportation Systems, located at KTH Campus Valhallavägen, designed and developed by Naveen Mohan and others.This particular respository serves as a store for the work performed during the first application made by AD-EYE to become an authorised test site for AD testing in Stockholm, Sweden. This application used AD-EYE code integrated with the Research Concept Vehicle from the ITRL lab at KTH.This repository contains work from theITRL team in the form of the RCV-E Capella libraryAD-EYE team in modelling the ADI in CapellaAD-EYE team in performing the analysis of the integrated system using the ATRIUM process.Note: The folder "Capella" contains the base software capella MBSE and requires java jre-8u221.Once launched, by chosing the workspace "workspace", the user will be able to see and modify the model of ADI and its related library : RCVE.The Atrium VP v1.0.0 has been added in the dropins folder of the base capella software. Although it can be used in both branches, the branch ADI_and_RCVE does not contain any Atrium elements. The Capella model in the branch Atrium_process contains the start an Atrium iteration, and can be continued by opening the Atrium UI on the diagram "Atrium process diagram" of ADI.
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| 6. |
- Mohan, Naveen, et al.
(författare)
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ATRIUM - Architecting Under Uncertainty for ISO 26262 compliance
- 2017
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Ingår i: 2017 11TH ANNUAL IEEE INTERNATIONAL SYSTEMS CONFERENCE (SYSCON). - : IEEE. - 9781509046232 ; , s. 786-793
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Konferensbidrag (refereegranskat)abstract
- The ISO 26262 is currently the dominant functional safety standard for electrical and electronic systems in the automotive industry. The Functional Safety Concept sub-phase in the standard requires the Preliminary Architectural Assumptions (PAA) for allocation of functional safety requirements. This paper justifies the need for, and defines a process ATRIUM, for consistent design of the PAA. ATRIUM is subsequently applied in an industrial case study for a function enabling highly automated driving at one of the largest heavy vehicle manufacturers in Europe, Scania CV AB. The findings from this study, which contributed to ATRIUM's institutionalization at Scania, are presented. The benefits of ATRIUM include (i) a fast and flexible way to refine the PAA, and a framework to (ii) incorporate information from legacy systems into safety design and (iii) rigorously track and document the assumptions and rationale behind architectural decisions under uncertain information. The contributions of this paper are (i) the analysis of the problem (ii) the process ATRIUM and (iii) findings and the discussion from the case study at Scania.
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| 7. |
- Mohan, Naveen, et al.
(författare)
-
Challenges in architecting fully automated driving; With an emphasis on heavy commercial vehicles
- 2016
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Ingår i: Proceedings - 2016 Workshop on Automotive Systems/Software Architectures, WASA 2016. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781509025718 ; , s. 2-9
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Konferensbidrag (refereegranskat)abstract
- Fully automated vehicles will require new functionalities for perception, navigation and decision making - an Autonomous Driving Intelligence (ADI). We consider architectural cases for such functionalities and investigate how they integrate with legacy platforms. The cases range from a robot replacing the driver - with entire reuse of existing vehicle platforms, to a clean-slate design. Focusing on Heavy Commercial Vehicles (HCVs), we assess these cases from the perspectives of business, safety, dependability, verification, and realization. The original contributions of this paper are the classification of the architectural cases themselves and the analysis that follows. The analysis reveals that although full reuse of vehicle platforms is appealing, it will require explicitly dealing with the accidental complexity of the legacy platforms, including adding corresponding diagnostics and error handling to the ADI. The current fail-safe design of the platform will also tend to limit availability. Allowing changes to the platforms, will enable more optimized designs and fault-operational behaviour, but will require initial higher development cost and specific emphasis on partitioning and control to limit the influences of safety requirements. For all cases, the design and verification of the ADI will pose a grand challenge and relate to the evolution of the regulatory framework including safety standards.
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| 8. |
- Mohan, Naveen, et al.
(författare)
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OPEN-KTH : An Open Lidar Dataset of KTH Campus Valhallavägen
- 2021
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Annan publikationabstract
- OPEN-KTH: An open Lidar dataset of KTH campus VahlallavägenOpen-KTH is a subproject of the AD-EYE testbed for Automated Driving and Intelligent Transportation Systems.Learn more at https://www.adeye.se/open-kth or contact adeye@md.kth.seThe AD-EYE simulation platform is based on the description presented in the work:Naveen Mohan, Martin Törngren, "AD-EYE: A Co-Simulation Platform for Early Verification of Functional Safety Concepts", SAE Technical Paper 19AE-0203/2019-01-0126, https://doi.org/10.4271/2019-01-0126Preprint available at: https://arxiv.org/abs/1912.00448Data collected by students of the group "AD-EYE on Road" in the capstone course of the Mechatronics Masters program using the AD-EYE platform.Mapping using the collected data was performed by Maxime Sainte Catherine from the AD-EYE team.
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| 9. |
- Mohan, Naveen, et al.
(författare)
-
OPEN-KTH-3dMODELS: An Open Dataset of Building Models at KTH Campus Valhallavägen
- 2023
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Annan publikationabstract
- OPEN-KTH-3dMODELS: An open dataset of building models at KTH Campus ValhallavägenOpen-KTH-3dModels is a subproject of the AD-EYE testbed for Automated Driving and Intelligent Transportation Systems.The dataset comprises of a series .blend files that have prominent buildings from KTH campus Valhallavägen. The dataset also contains PreScan compatible models that can be used wtih AD-EYE (https://www.adeye.se/)Visualisation video: https://www.youtube.com/watch?v=F6NfCiul3oELearn more at https://www.adeye.se/open-kth-3dmodels or contact adeye@md.kth.se The AD-EYE testbed is based on the design presented in the work "AD-EYE: A Co-Simulation Platform for Early Verification of Functional Safety Concepts" Original paper: https://doi.org/10.4271/2019-01-0126Preprint available at: https://arxiv.org/abs/1912.00448Citation:Naveen Mohan, Martin Törngren, "AD-EYE: A Co-Simulation Platform for Early Verification of Functional Safety Concepts", SAE Technical Paper 19AE-0203/2019-01-0126, https://doi.org/10.4271/2019-01-0126 Notes:Modelling work primarily performed by Lester Jose, during his internship with AD-EYE.
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| 10. |
- Mohan, Naveen, et al.
(författare)
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System and Method for Controlling a Motor Vehicle to Drive Autonomously
- 2017
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Patent (populärvet., debatt m.m.)abstract
- A motor vehicle (MV) is controlled to drive autonomously in agreement with a nominal path in response to nominal control signals (NCS) from a bank of control units (110). Safety policies (P) are provided via a first data-interface unit (163). The safety policies (P) describe mission-related rules to be followed during operation of the motor vehicle (MV). The safety policies (P) are based on a safety case (SC) stipulating how the motor vehicle (MV) shall be controlled to meet a functional safety standard. A watch unit (160) receives sensor signals (SS) from the motor vehicle (MV), and based thereon repeatedly generates commands ({cmd}) to update the boundary conditions ({bc}) aiming at confining the nominal path within limits that are given by the sensor signals (SS) and the at least one safety policy (P). The bank of control units reads out the set of boundary conditions ({bc}) and controls the motor vehicle (MV) to move in such a manner that the nominal path satisfies the boundary conditions ({bc}), and is thus be considered to be safe.
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