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Larsson, L. V., Ericson, L., Uebel (Pettersson), K. & Krus, P. (2019). Low-Level Control of Hybrid Hydromechanical Transmissions for Heavy Mobile Working Machines. Energies, 12(9), Article ID 1683.
Open this publication in new window or tab >>Low-Level Control of Hybrid Hydromechanical Transmissions for Heavy Mobile Working Machines
2019 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 9, article id 1683Article in journal (Refereed) Published
Abstract [en]

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. 

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
hydromechanical transmissions, hybridization, control, construction machinery; decoupled control, hardware-in-the-loop
National Category
Other Mechanical Engineering
Identifiers
urn:nbn:se:liu:diva-157504 (URN)10.3390/en12091683 (DOI)000469761700099 ()
Funder
Swedish Energy Agency, P39367-2
Note

Funding agencies: Swedish Energy Agency (Energimyndigheten) [P39367-2]

Available from: 2019-06-14 Created: 2019-06-14 Last updated: 2019-08-21Bibliographically approved
Baer, K., Ericson, L. & Krus, P. (2019). Robustness and performance evaluations for simulation-based control and component parameter optimization for a series hydraulic hybrid vehicle. Engineering optimization (Print), 1-19
Open this publication in new window or tab >>Robustness and performance evaluations for simulation-based control and component parameter optimization for a series hydraulic hybrid vehicle
2019 (English)In: Engineering optimization (Print), ISSN 0305-215X, E-ISSN 1029-0273, p. 1-19Article in journal (Refereed) Epub ahead of print
Abstract [en]

Simulation-based optimization is a useful tool in the design of complex engineering products. Simulation models are used to capture numerous aspects of the design problem for the objective function. Optimization results obtained can be assessed from various perspectives. In this study, component and control optimization of a series hydraulic hybrid vehicle is used as an application, and different robustness and performance aspects are evaluated. Owing to relatively high computational loads, efficient optimization algorithms are important to provide sufficient quality of results at reasonable computational costs. To estimate problem complexity and evaluate optimization algorithm performance, the definitions for information entropy and the related performance index are extended. The insights gained from various simulation-based optimization experiments and their subsequent analysis help characterize the efficiency of the optimization problem formulation and parameterization, as well as optimization algorithm selection with respect to parallel computation capabilities for further development of the model and optimization framework.

Place, publisher, year, edition, pages
Taylor & Francis, 2019
Keywords
Simulation-based optimization, information entropy-rate-based performance index, robustness analysis, direct search optimization, hydraulic hybrid vehicle
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:liu:diva-156185 (URN)10.1080/0305215X.2019.1590566 (DOI)
Available from: 2019-04-08 Created: 2019-04-08 Last updated: 2019-04-15Bibliographically approved
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)000460491500042 ()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
Note

Funding agencies: Swedish Energy Agency

Available from: 2019-02-04 Created: 2019-02-04 Last updated: 2019-08-21Bibliographically 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
Hochwallner, M., Pinto, L. & Krus, P. (2018). Tracking Control for High-Performance Motion of a Hydraulic Infinite Linear Actuator. IEEE/ASME transactions on mechatronics, 23(6), 2782-2793
Open this publication in new window or tab >>Tracking Control for High-Performance Motion of a Hydraulic Infinite Linear Actuator
2018 (English)In: IEEE/ASME transactions on mechatronics, ISSN 1083-4435, E-ISSN 1941-014X, Vol. 23, no 6, p. 2782-2793Article in journal (Refereed) Published
Abstract [en]

The concept of the hydraulic infinite linear actuator consists of two double-acting cylinders with hydraulically detachable pistons driving a common rod. Alternatingly, one cylinder engages and drives the load, whereas the other retracts; the actuator, thus, works in a kind of rope-climbing motion. The actuator has three degrees of freedom, which are temporarily coupled compared with one in a conventional cylinder. Hence, the actuator is a hybrid system with both continuous and discrete states and control inputs. This paper presents a tracking control problem and a solution for high-performance motion, which is interpreted as utilizing the hardware limits in the sense of velocity, accuracy, smoothness, and usability. The concept is demonstrated by simulation for the case of a rest-to-rest motion, but the intended use cases also include arbitrary trajectories.

Place, publisher, year, edition, pages
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2018
Keywords
Hybrid system; hydraulic servo system; infinite motion; linear hydraulic actuator; tracking problem
National Category
Control Engineering
Identifiers
urn:nbn:se:liu:diva-153684 (URN)10.1109/TMECH.2018.2871865 (DOI)000453560200025 ()2-s2.0-85054223956 (Scopus ID)
Available from: 2019-01-07 Created: 2019-01-07 Last updated: 2019-08-19
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
Larsson, L. V. & Krus, P. (2017). Displacement Control Strategies of an In-Line Axial-Piston Unit. In: Petter Krus, Liselott Ericson and Magnus Sethson (Ed.), Proceedings of 15:th Scandinavian International Conference on Fluid Power, June 7-9, 2017, Linköping, Sweden: . Paper presented at The 15th Scandinavian International Conference on Fluid Power, SICFP’17, June 7-9, 2017, Linköping, Sweden (pp. 244-253). Linköping: Linköping University Electronic Press, 144
Open this publication in new window or tab >>Displacement Control Strategies of an In-Line Axial-Piston Unit
2017 (English)In: Proceedings of 15:th Scandinavian International Conference on Fluid Power, June 7-9, 2017, Linköping, Sweden / [ed] Petter Krus, Liselott Ericson and Magnus Sethson, Linköping: Linköping University Electronic Press, 2017, Vol. 144, p. 244-253Conference paper, Published paper (Refereed)
Abstract [en]

The need for efficient propulsion in heavy vehicles has led to an increased interest in hybrid solutions. Hydraulic hybrids rely on variable hydraulic pumps/motors to continuously convert between hydraulic and mechanical power. This process is carried out via the implementation of secondary control which, in turn, is dependent on a fast displacement controller response. This paper reports on a study of a prototype axial piston pump of the in-line type, in which the displacement is measured with a sensor and controlled using a software-based controller. A pole placement control approach is used, in which a simple model of the pump is used to parametrise the controller using desired resonance and damping of the closed loop controller as input. The controller’s performance is tested in simulations and hardware tests on the prototype unit. The results show that the pole placement approach combined with a lead-compensator controller architecture is flexible, easy to implement and is able to deliver a fast response with high damping. The results will in the future be used in further research on full-vehicle control of heavy hydraulic hybrids.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2017
Series
Linköping Electronic Conference Proceedings, ISSN 1650-3686, E-ISSN 1650-3740 ; 144
Keywords
Hydraulic hybrids, displacement control, pole placement
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:liu:diva-139854 (URN)10.3384/ecp17144244 (DOI)9789176853696 (ISBN)
Conference
The 15th Scandinavian International Conference on Fluid Power, SICFP’17, June 7-9, 2017, Linköping, Sweden
Available from: 2017-08-17 Created: 2017-08-17 Last updated: 2019-08-21Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-2315-0680

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