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Larsson, L. V. & Krus, P. (2018). A General Approach to Low-Level Control of Heavy Complex Hybrid Hydromechanical Transmissions. In: BATH/ASME 2018 Symposium on Fluid Power and Motion Control: . Paper presented at BATH/ASME 2018 Symposium on Fluid Power and Motion Control, Bath, United Kingdom, September 12-14, 2018.
Open this publication in new window or tab >>A General Approach to Low-Level Control of Heavy Complex Hybrid Hydromechanical Transmissions
2018 (English)In: BATH/ASME 2018 Symposium on Fluid Power and Motion Control, 2018Conference paper, Published paper (Refereed)
Abstract [en]

This paper focuses on the low-level control of heavy complex hydraulic hybrids, taking stability and the dynamic properties of the included components into account. A linear model which can describe a high number of hybrid configurations in a straightforward manner is derived and used for the development of a general multiple input multiple output (MIMO) decoupling control strategy. This strategy is tested in non-linear simulations of an example vehicle and stability requirements for the low-level actuators are derived. The results show that static decoupling may be used to simplify the control problem to three individual loops controlling pressure, output speed and engine speed. In particular, the pressure and output speed loops rely on fast displacement controllers for stability. In addition, it was found that the decoupling is facilitated if the hydrostatic units have equal response. The low-level control of heavy complex hydraulic hybrids may thus imply other demands on actuators than what is traditionally assumed.

Keywords
Control, Multiple input multiple output control, heavy hydraulic hybrids, hydromechanical transmissions
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:liu:diva-154306 (URN)10.1115/FPMC2018-8877 (DOI)2-s2.0-85058056485 (Scopus ID)978-0-7918-5196-8 (ISBN)
Conference
BATH/ASME 2018 Symposium on Fluid Power and Motion Control, Bath, United Kingdom, September 12-14, 2018
Funder
Swedish Energy Agency, P39367-2
Available from: 2019-02-04 Created: 2019-02-04 Last updated: 2019-02-14Bibliographically approved
Baer, K., Ericson, L. & Krus, P. (2018). Framework for simulation-based simultaneous system optimization for a series hydraulic hybrid vehicle. International Journal of Fluid Power
Open this publication in new window or tab >>Framework for simulation-based simultaneous system optimization for a series hydraulic hybrid vehicle
2018 (English)In: International Journal of Fluid Power, ISSN 1439-9776Article in journal (Refereed) Epub ahead of print
Abstract [en]

Hybridisation of hydraulic drivetrains offers the potential of efficiency improvement for on – and off-road applications. To realise the advantages, a carefully designed system and corresponding control strategy are required, which are commonly obtained through a sequential design process. Addressing component selection and control parameterisation simultaneously through simulation-based optimisation allows for exploration of a large design space as well as design relations and trade-offs, and their evaluation in dynamic conditions which exist in real driving scenarios. In this paper, the optimisation framework for a hydraulic hybrid vehicle is introduced, including the simulation model for a series hybrid architecture and component scaling considerations impacting the system’s performance. A number of optimisation experiments for an on-road light-duty vehicle, focused on standard-drive-cycle-performance, illustrate the impact of the problem formulation on the final design and thus the complexity of the design problem. The designs found demonstrate both the potential of energy storage in series hybrids, via an energy balance diagram, as well as some challenges. The framework presented here provides a base for systematic evaluation of design alternatives and problem formulation aspects.

Place, publisher, year, edition, pages
Taylor & Francis, 2018
Keywords
Simulation-based optimization, hydraulic hybrid vehicle, series hybrid, simultaneous design and control optimization, Hopsan
National Category
Computer Systems
Identifiers
urn:nbn:se:liu:diva-152353 (URN)10.1080/14399776.2018.1527122 (DOI)2-s2.0-85055674140 (Scopus ID)
Available from: 2018-10-29 Created: 2018-10-29 Last updated: 2018-11-23Bibliographically approved
Larsson, L. V. & Krus, P. (2018). Hardware-in-the-loop Simulation of Complex Hybrid Hydromechanical Transmissions. In: WIEFP2018 – 4th Workshop on Innovative Engineering for Fluid Power, November 28-30, Sao Paulo, Brazil: . Paper presented at WIEFP2018 – 4th Workshop on Innovative Engineering for Fluid Power, November 28-30, Sao Paulo, Brazil (pp. 69-73). Linköping, 156, Article ID 014.
Open this publication in new window or tab >>Hardware-in-the-loop Simulation of Complex Hybrid Hydromechanical Transmissions
2018 (English)In: WIEFP2018 – 4th Workshop on Innovative Engineering for Fluid Power, November 28-30, Sao Paulo, Brazil, Linköping, 2018, Vol. 156, p. 69-73, article id 014Conference paper, Published paper (Refereed)
Abstract [en]

Fuel efficiency and environmental concerns are factors that drive the development of complex solutions for propulsion in heavy working machines. Although these solutions, such as power-split hydromechanical transmissions and hydraulic hybrids, indeed are promising in terms of energy efficiency, they also tend to increase the dependency on accurate, stable control. The realization of this aspect, in turn, relies on continuous testing throughout the development process, usually carried out on expensive, time-consuming prototypes. To lower the development costs and time, hardware-in-the-loop (HWIL) simulations may be introduced as a middle-way between pure prototyping and computer-based simulations. In this concept, some parts of the transmission are represented as hardware while others are included as mathematical models running in real-time in a data acquisition system. This mix of hardware and software allows for high versatility while maintaining a high level of reliability of the results. This paper reports on parts of a study on HWIL simulations of heavy complex hybrid hydromechanical transmissions. Control algorithms for the hardware/model interface in a test rig are derived and their performance are evaluated in HWIL simulations of a mid-sized wheel loader. The results show the importance of fast rig controllers to capture the fast dynamics of the software simulations. It was also found that an important aspect of HWIL simulations is that they are well aligned with their purpose. If so, the simulation yields more reliable knowledge, which is of higher use in the design process of these complex systems. To summarize, HWIL simulations may, if implemented properly, be an important asset in the development of heavy complex hybrid hydromechanical transmissions.

Place, publisher, year, edition, pages
Linköping: , 2018
Series
Linköping Electronic Conference Proceedings, ISSN 1650-3686, E-ISSN 1650-3740
Keywords
Hardware-in-the-loop-simulations, hydromechanical transmissions, heavy hydraulic hybrid vehicles
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:liu:diva-154304 (URN)10.3384/ecp1815669 (DOI)978-91-7685-136-4 (ISBN)
Conference
WIEFP2018 – 4th Workshop on Innovative Engineering for Fluid Power, November 28-30, Sao Paulo, Brazil
Funder
Swedish Energy Agency, P39367-2
Available from: 2019-02-04 Created: 2019-02-04 Last updated: 2019-02-14Bibliographically approved
Sobron, A., Lundström, D., Larsson, R., Krus, P. & Jouannet, C. (2018). Methods for efficient flight testing and modelling of remotely piloted aircraft within visual line-of-sight. In: The International Council of the Aeronautical Sciences (Ed.), Proceedings of the 31st Congress of The International Council of the Aeronautical Sciences (ICAS), September 9-14 2018, Belo Horizonte, Brazil.: . Paper presented at 31st Congress of The International Council of the Aeronautical Sciences (ICAS), September 9-14 2018, Belo Horizonte, Brazil.. Bohn
Open this publication in new window or tab >>Methods for efficient flight testing and modelling of remotely piloted aircraft within visual line-of-sight
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2018 (English)In: Proceedings of the 31st Congress of The International Council of the Aeronautical Sciences (ICAS), September 9-14 2018, Belo Horizonte, Brazil. / [ed] The International Council of the Aeronautical Sciences, Bohn, 2018Conference paper, Published paper (Refereed)
Abstract [en]

Remotely piloted scaled models not only serve as convenient low-risk flying test-beds but also can provide useful data and increase confidence in an eventual full-scale design. Nevertheless, performing advanced flight tests in a safe and cost-effective manner is often a challenge for organizations with limited resources. A typical scenario is testing within visual line-of-sight at very low altitude, a type of operation that offers major cost advantages at the expense of a reduced available airspace. This paper describes some of the authors' work towards efficient performance evaluation and system identification of fixed-wing, remotely piloted aircraft under these challenging conditions. Results show that certain techniques, manoeuvre automation, and platform-optimised multisine input signals can improve the flight test efficiency and the modelling process. It is also probable that some of the benefits observed here could be extrapolated to flight testing beyond visual line-of-sight or even to full-scale flight testing.

Place, publisher, year, edition, pages
Bohn: , 2018
Keywords
flight testing, system identification, flight mechanics, modelling and simulation, RPAS
National Category
Aerospace Engineering
Identifiers
urn:nbn:se:liu:diva-155052 (URN)978-3-932182-88-4 (ISBN)
Conference
31st Congress of The International Council of the Aeronautical Sciences (ICAS), September 9-14 2018, Belo Horizonte, Brazil.
Projects
MSDEMO
Available from: 2019-03-11 Created: 2019-03-11 Last updated: 2019-03-22Bibliographically approved
Hällqvist, R., Schminder, J., Eek, M., Braun, R., Gårdhagen, R. & Krus, P. (2018). NOVEL FMI AND TLM-BASED DESKTOP SIMULATOR FORDETAILED STUDIES OF THERMAL PILOT COMFORT. In: ICAS congress proceeding: . Paper presented at 31st Congress of the International Council of the Aeronautical Sciences,Belo Horizonte, Brazil, September 9-14, 2018. International Council of the Aeronautical Sciences, Article ID ICAS2018_0203.
Open this publication in new window or tab >>NOVEL FMI AND TLM-BASED DESKTOP SIMULATOR FORDETAILED STUDIES OF THERMAL PILOT COMFORT
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2018 (English)In: ICAS congress proceeding, International Council of the Aeronautical Sciences , 2018, article id ICAS2018_0203Conference paper, Published paper (Other academic)
Abstract [en]

Modelling and Simulation is key in aircraft systemdevelopment. This paper presents a novel,multi-purpose, desktop simulator that can beused for detailed studies of the overall performanceof coupled sub-systems, preliminary controldesign, and multidisciplinary optimization.Here, interoperability between industrially relevanttools for model development and simulationis established via the Functional MockupInterface (FMI) and System Structure andParametrization (SSP) standards. Robust anddistributed simulation is enabled via the TransmissionLine element Method (TLM). The advantagesof the presented simulator are demonstratedvia an industrially relevant use-case wheresimulations of pilot thermal comfort are coupledto Environmental Control System (ECS) steadystateand transient performance.

Place, publisher, year, edition, pages
International Council of the Aeronautical Sciences, 2018
Keywords
OMSimulator; FMI; TLM; Pilot Thermal Comfort; Modelling and Simulation
National Category
Applied Mechanics Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-152897 (URN)978-3-932182-88-4 (ISBN)
Conference
31st Congress of the International Council of the Aeronautical Sciences,Belo Horizonte, Brazil, September 9-14, 2018
Available from: 2018-11-27 Created: 2018-11-27 Last updated: 2018-11-27
Pettersson, K., Heybroek, K., Mattsson, P. & Krus, P. (2017). A novel hydromechanical hybrid motion system for construction machines. International Journal of Fluid Power, 18(1), 17-28
Open this publication in new window or tab >>A novel hydromechanical hybrid motion system for construction machines
2017 (English)In: International Journal of Fluid Power, ISSN 1439-9776, Vol. 18, no 1, p. 17-28Article in journal (Refereed) Published
Abstract [en]

This paper deals with a novel type of hybrid motion system for construction machines based on a common pressure rail shared between a hydromechanical power-split transmission and secondary controlled work hydraulics. A construction machine with driveline and work functions is a complex coupled motion system and the design of an effective hybrid system needs to take both subsystems into account. Studies on energy efficient hybrid systems for construction machines have hitherto principally focused on one subsystem at a time - work hydraulics or driveline. The paper demonstrates a use case with a specific transmission concept proposal for a medium-sized wheel loader. The system is modelled and simulated using an optimal energy management strategy based on dynamic programming. The results show the benefits of a throttle-free bidirectional link between the machine's subsystems and the energy storage, while taking advantage of the complex power flows of the power-split transmission.

Place, publisher, year, edition, pages
Abingdon, UK: Taylor & Francis, 2017
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:liu:diva-142329 (URN)10.1080/14399776.2016.1210423 (DOI)
Available from: 2017-10-26 Created: 2017-10-26 Last updated: 2017-11-09Bibliographically approved
Sobron, A., Lundström, D., Krus, P., Jouannet, C. & Sandoval Goez, L. C. (2017). Flight test design for remotely-piloted aircraft in confined airspace. In: The Council of European Aerospace Societies (Ed.), 6th CEAS Air and Space Conference, Aerospace Europe, 16-20 October, 2017, Bucharest, Romania.: . Paper presented at 6th CEAS Air and Space Conference, Aerospace Europe, 16-20 October, 2017, Bucharest, Romania.. Brussels
Open this publication in new window or tab >>Flight test design for remotely-piloted aircraft in confined airspace
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2017 (English)In: 6th CEAS Air and Space Conference, Aerospace Europe, 16-20 October, 2017, Bucharest, Romania. / [ed] The Council of European Aerospace Societies, Brussels, 2017Conference paper, Published paper (Refereed)
Abstract [en]

Thispaper presents various techniques and procedures that aim to simplify flighttesting of fixed-wing, remotely-piloted aircraft with the purposes ofperformance evaluation and system identification. These methods have beenspecifically developed for flight within visual line-of-sight, a type ofoperation that limits the available airspace severely but offers major costadvantages considering the current regulations for unmanned flight in mostWestern countries.

Place, publisher, year, edition, pages
Brussels: , 2017
Keywords
flight testing, visual line-of-sight, UAS, data acquisition, flight dynamics
National Category
Aerospace Engineering
Identifiers
urn:nbn:se:liu:diva-155054 (URN)
Conference
6th CEAS Air and Space Conference, Aerospace Europe, 16-20 October, 2017, Bucharest, Romania.
Projects
MSDEMO
Available from: 2019-03-11 Created: 2019-03-11 Last updated: 2019-03-22Bibliographically approved
Hochwallner, M. & Krus, P. (2017). Hydraulic Infinite Linear Actuator -- The Ballistic Gait: Digital Hydro-Mechanical Motion. In: : . Paper presented at 15th Scandinavian International Conference on Fluid Power, SICFP’17, Linköping, Sweden, Juni 7-9, 2017. Linköping, Sweden
Open this publication in new window or tab >>Hydraulic Infinite Linear Actuator -- The Ballistic Gait: Digital Hydro-Mechanical Motion
2017 (English)Conference paper, Published paper (Refereed)
Abstract [en]

The Hydraulic Infinite Linear Actuator, HILA, has been presented in previous publications. The novel actuator consists of one, two or more double-acting cylinders witha common piston rod and hydraulically detachable pistons. In the basic gait, one cylinderalternatingly engages and drives the load while the other retracts. The HILA thus works in akind of rope-climbing motion. The concept also allows other gaits, i.e. patterns of motion.This contribution focuses on the ballistic gait, a pattern of motion where one cylinder engagesto give the load a push. The load then carries on with its motion by inertia, cylinders disen-gaged. The actuator thus realizes hydro-mechanical pulse-frequency modulation (PFM).This gait is energy efficient and able to recuperate energy.

Place, publisher, year, edition, pages
Linköping, Sweden: , 2017
Keywords
novel actuator, infinite linear motion, digital fluid power, digital hydromechanical motion, energy recuperation
National Category
Other Mechanical Engineering
Identifiers
urn:nbn:se:liu:diva-142416 (URN)
Conference
15th Scandinavian International Conference on Fluid Power, SICFP’17, Linköping, Sweden, Juni 7-9, 2017
Available from: 2017-10-30 Created: 2017-10-30 Last updated: 2017-11-23Bibliographically approved
Hochwallner, M. & Krus, P. (2017). Motion Control Concepts For The Hydraulic Infinite Linear Actuator. In: : . Paper presented at ASME 2016 9th FPNI Ph.D Symposium on Fluid Power -- FPNI2016. ASME Press, Article ID UNSP V001T01A017.
Open this publication in new window or tab >>Motion Control Concepts For The Hydraulic Infinite Linear Actuator
2017 (English)Conference paper, Published paper (Refereed)
Abstract [en]

This contribution presents the novel Hydraulic Infinite Linear Actuator (HILA). It focuses on the control of motion and is based on simulation and analysis. The novel actuator consists of two symmetric double acting cylinders with a common piston rod and hydraulically detachable pistons. Alternatingly one cylinder engages and drives the load while the other retracts, the HILA thus works in a kind of rope climbing motion. The purpose of this contribution is to study the motion control of the HILA and to mimic the behaviour of a conventional cylinder. The HILA has three degrees of freedom which are temporarily coupled compared with one in a conventional cylinder. Further, the HILA with the chosen hydraulic system has two continuous and two digital control inputs. The challenge to be tackled is to combine the short stroke back and forth motions of the cylinders into a continuous smooth motion of the whole actuator. Results from simulations and analyses show that the investigated concepts can keep the jerk within acceptable limits for many applications.

Place, publisher, year, edition, pages
ASME Press, 2017
Keywords
novel actuator, infinite linear stroke, cylinder, control
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:liu:diva-136125 (URN)10.1115/FPNI2016-1523 (DOI)000398986900017 ()2-s2.0-85008258420 (Scopus ID)978-0-7918-5047-3 (ISBN)
Conference
ASME 2016 9th FPNI Ph.D Symposium on Fluid Power -- FPNI2016
Available from: 2017-03-28 Created: 2017-03-28 Last updated: 2017-05-05Bibliographically approved
Braun, R. & Krus, P. (2017). Parallel Implementations of the Complex-RF Algorithm. Engineering optimization (Print), 49(9), 1558-1572
Open this publication in new window or tab >>Parallel Implementations of the Complex-RF Algorithm
2017 (English)In: Engineering optimization (Print), ISSN 0305-215X, E-ISSN 1029-0273, Vol. 49, no 9, p. 1558-1572Article in journal (Refereed) Published
Abstract [en]

Even though direct-search optimization methods are more difficult to parallelize than population-based methods, there are many unexploited opportunities. Five methods for parallelizing the Complex-RF methods have been implemented and evaluated. Three methods are based on the unchanged original algorithm, while two require modifications. The methods have been tested on two test function and one real simulation model. An analysis of the algorithm has been performed. This provides a basis for parametrization of the parallel methods. Without changing the original algorithm, speed-up of 2.5-3 is achieved. With allowing modifications, a speed-up of up to 5 is obtained without significantly reducing the probability of finding the global minimum. Speed-up does not scale linear to the number of threads. When more threads are added, parallelization efficiency decreases. However, a comparison with a particle swarm method shows that Complex-RF performs better regardless of the number of threads, due to its fast convergence rate.

Place, publisher, year, edition, pages
Taylor & Francis, 2017
Keywords
Parallel optimization, direct-search, simplex, Complex-RF
National Category
Electrical Engineering, Electronic Engineering, Information Engineering Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:liu:diva-122751 (URN)10.1080/0305215X.2016.1260712 (DOI)000404810100006 ()
Note

The prevuous status of this article was Manuscript.

Available from: 2015-11-19 Created: 2015-11-19 Last updated: 2017-08-09Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-2315-0680

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