Distributed System Simulation Methods : For Model-Based Product Development

Braun, Robert

doi:10.3384/diss.diva-122754

Cited by 8 publications

(12 citation statements)

References 70 publications

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“…The model used to describe the surroundings of the hydraulic circuit was implemented in Hopsan, a system simulation tool developed at Linköping University [34]. This software is based on the Transmission Line element Method (TLM), which considers the constant time delays present in physical elements [35].…”

Section: Hopsan Modelmentioning

confidence: 99%

Low-Level Control of Hybrid Hydromechanical Transmissions for Heavy Mobile Working Machines

et al. 2019

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Fuel efficiency has become an increasingly important property of heavy mobile working machines. As a result, Hybrid Hydromechanical Transmissions (HMTs) are often considered for the propulsion of these vehicles. The introduction of hybrid HMTs does, however, come with a number of control-related challenges. To date, a great focus in the literature has been on high-level control aspects, concerning optimal utilization of the energy storage medium. In contrast, the main topic of this article is low-level control, with the focus on dynamic response and the ability to realize requested power flows accurately. A static decoupled Multiple-Input-Multiple-Output (MIMO) control strategy, based on a linear model of a general hybrid HMT, is proposed. The strategy is compared to a baseline approach in Hardware-In-the-Loop (HWIL) simulations of a reference wheel loader for two drive cycles. It was found that an important benefit of the decoupled control approach is that the static error caused by the system’s cross-couplings is minimized without introducing integrating elements. This feature, combined with the strategy’s general nature, motivates its use for multiple-mode transmissions in which the transmission configuration changes between the modes.

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Section: Hopsan Modelmentioning

confidence: 99%

Low-Level Control of Hybrid Hydromechanical Transmissions for Heavy Mobile Working Machines

et al. 2019

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“…Hopsan is based on the Transmission Line Modelling (TLM) method, in which the transmission components may be modelled individually and separated by transmission line elements. This decouples the components from each other in time and enables fast parallel simulation using distributed equation solvers [46]. The full vehicle model is shown in figure 3.5.…”

Section: Modelmentioning

confidence: 99%

Control Aspects of ComplexHydromechanical Transmissions: with a Focus on Displacement Control

Larsson¹

2017

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This thesis deals with control aspects of complex hydromechanical transmissions. The overall purpose is to increase the knowledge of important aspects to consider during the development of hydromechanical transmissions to ensure transmission functionality. These include ways of evaluating control strategies in early design stages as well as dynamic properties and control aspects of displacement controllers, which are key components in these systems.Fuel prices and environmental concerns are factors that drive research on propulsion in heavy construction machinery. Hydromechanical transmissions are strong competitors to conventional torque-converter transmissions used in this application today. They offer high efficiency and wide speed/torque conversion ranges, and may easily be converted to hybrids that allow further fuel savings through energy recuperation. One challenge with hydromechanical transmissions is that they offer many different configurations, which in turn makes it important to enable evaluation of control aspects in early design stages. In this thesis, hardware-in-the-loop simulations, which blend hardware tests and standard software-based simulations, are considered to be a suitable method. A multiple-mode transmission applied to a mid-sized construction machine is modelled and evaluated in offline simulations as well as in hardware-in-the-loop simulations.Hydromechanical transmissions rely on efficient variable pumps/motors with fast, accurate displacement controllers. This thesis studies the dynamic behaviour of the displacement controller in swash-plate axial-piston pumps/motors. A novel control approach in which the displacement is measured with an external sensor is proposed. Performance and limitations of the approach are tested in simulations and in experiments. The experiments showed a significantly improved performance with a controller that is slightly more advanced than a standard proportional controller. The implementation of the controller allows simple tuning and good predictability of the displacement response.

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“…In this way a time delay is introduced between capacitive and resistive components. Compared to the centralized solver approach, this facilitates a higher degree of numerical isolation of components which, may serve as an enabler for parallelization of model equations for simulation on multi-core platforms (Braun, 2015), (Sjölund et al, 2010). TLM is used in the M&S tool HOPSAN 6 developed at Linköping University.…”

Section: Istributed M Odelingmentioning

confidence: 99%

On Credibility Assessment in Aircraft System Simulation

Eek¹

2016

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HE aeronautical industry is becoming increasingly reliant on Modeling and Simulation (M&S) for use throughout all system development phases, for system verification, and end-user training. To justify and to utilize the full potential of today's model-based approach and to enable the industrially requested transition towards virtual testing and virtual certification, the development of efficient and industrially applicable methods for M&S credibility assessment is a key challenge. Credibility assessment of an M&S effort using one individual simulation model is undoubtedly a challenging task involving several vital aspects like verification, validation, uncertainty quantification, and model use history. Building confidence in simulator applications in which several individual models are connected and simulated together is even more problematic.This work addresses methods facilitating credibility assessment of simulation models and simulator applications used in aircraft system development. For models of individual aircraft subsystems, like liquid cooling or environmental control systems, an uncertainty aggregation method is proposed that facilitates early model validation through approximate uncertainty quantification. The central idea is to integrate information obtained during component level validation directly into the component equations, and to utilize this information in model level uncertainty quantification. The method is applicable in early development phases when the availability of system level measurement data for traditional model validation purposes is typically very limited. To clarify, the model may describe a system not yet realized, neither in a test rig nor in a test aircraft.In addition to methods intended for models of individual subsystems, this work also proposes a method and an associated tool for credibility assessment of large-scale simulator applications. As a complement to traditional document-centric approaches, static and dynamic credibility information is here presented to end-users directly during simulation. This implies a support for detecting test plan deficiencies, or that a simulator configuration is not a suitable platform for the execution of a particular test. The credibility assessment tool has been implemented and evaluated in two large-scale system simulators for the Saab Gripen fighter aircraft. The work presented herein also includes an industrially applicable workflow for development, validation, and export of simulation models.Thanks to the close connection to industry, some of the research results have already been successfully implemented in operations and are currently in industrial use. T vii Populärvetenskaplig SammanfattningLYGINDUSTRIN förlitar sig i allt högre utsträckning på modellering och simulering inom såväl systemutveckling som verifiering, samt för träning av piloter och flygtekniker. För att kunna styrka och dra maximal nytta av dagens modellbaserade arbetssätt krävs utveckling av effektiv och industriellt relevant metodik för bedömning av tro...

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Distributed System Simulation Methods : For Model-Based Product Development

Cited by 8 publications

References 70 publications

Low-Level Control of Hybrid Hydromechanical Transmissions for Heavy Mobile Working Machines

Low-Level Control of Hybrid Hydromechanical Transmissions for Heavy Mobile Working Machines

Control Aspects of ComplexHydromechanical Transmissions: with a Focus on Displacement Control

On Credibility Assessment in Aircraft System Simulation

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