| 1. |
- Björn, Eriksson, 1981-, et al.
(författare)
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Energy saving system utilizing LQ-technique design
- 2009
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Ingår i: Proceedings of the Seventh International Conference on Fluid Power Transmission and Control. - Beijing : Beijing World Publishing Corporation. ; , s. 224-229
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Konferensbidrag (refereegranskat)abstract
- This paper deals with the control of individual metering systems. This paper deals with the control of an individual metering system that could be used for reducing metering losses by enabling recuperation and regeneration operation. A system that utilizes individual metering is more flexible than a conventional system since there are more control signals and thereby more outputs to control. Energy saving aspects is among the main reasons for the research on this kind of system, but there is also an opportunity of improvements of the dynamics compared to a conventional system. In this paper an approach with LQtechnique are presented for improvements of system dynamics. Since all states in the system can not be measured a state observer is also considered in the control design. These work present simulations, implementations in a real world forwarder application and results from verifying experiments.
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| 2. |
- Degerman, Pär, 1976-, et al.
(författare)
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A Full Four-Quadrant Hydraulic Steering Actuator Applied to a Fully Automatic Passenger Vehicle Parking System
- 2006
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Ingår i: Proceedings of the 4th FPNI-PhD Symposium. - Lafayettem, IN, USA : FPNI Fluid Power Net Publications. - 1424304997 ; , s. 387-396
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Konferensbidrag (refereegranskat)abstract
- This project describes how the Active Pinion hydraulic steering system can be used to replace a electric power steering actuator in the Parking Pilot automatic parking system.Customer demand for fully or semi automatic parking systems in passenger cars, are getting higher with increased cost of parking related body damage repair coupled with restricted rearward sight and the larger dimensions of modern cars. This, however, puts new demands on the steering actuator. An automatic parking system requires full control of the steering servo, which is not possible with current hydraulic actuators. Instead these systems have to rely on electric servos which allow for the needed controllability.All current electric steering servos have the drawback that it is impossible to use them on anything but small or medium sized cars. Since a parking system can be seen as a premium accessory, which is more likely to attract customers who buy larger cars, this is a major hindrance for the success of automatic parking systems.A solution to the problem is to construct a controllable variant of the hydraulic steering servo, the Active Pinion. In this concept a small electric pilot motor is added to the traditional hydraulic valve, which adds one additional degree of freedom to the servo, accomplishing full four-quadrant operations.The project discusses how the Active Pinion concept is introduced in the Parking Pilot parking system and how different demands on the parking system relates to the performance of the actuator. The parking system is installed in a prototype car and simulation of the Active Pinion concept is accomplished with HWIL simulation in a load simulator.
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| 3. |
- Eriksson, Björn, 1981-, et al.
(författare)
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A High Energy Efficient Mobile Fluid Power System : Novel System Layout and Measurements
- 2008
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This is one of the earliest publications of the proposed energy efficient individual metering system shown in chapter 5, section 5.3.3. This paper introduces the novel system design, which utilizes independent meter-in and meter-out valves. This system design has the potential to increase energy efficiency considerably in a system that consists of a pump connected to more than one fluid power actuator. The system proposed here is not dependent on pressure transducers for either flow control or mode selection. The main difference between the work presented in this paper and earlier work is the control strategy. The output signal choices in the closed loops are new. Some functionality is kept in hardware to avoid critical sensor dependency. The presented system uses pressure compensators to achieve desired flows.
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| 4. |
- Eriksson, Björn, 1981-, et al.
(författare)
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An LQ-Control Approach for Independent Metering Systems
- 2009
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Ingår i: 11th Scandinavian International Conference on Fluid Power, SICFP'09, Linköping, Sweden, 2nd-4th June. - Linköping.
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Konferensbidrag (refereegranskat)abstract
- This paper deals with the control of an individual metering fluid power system. There are a number of reasons to use individual metering technology, one is flexibility. In traditional valves there is a mechanical connection between the meter-in orifice and the meter-out orifice. By control this orifices individually one valve can be used in different applications without hard- ware modifications. Instead of change spool the software is changed. Since there are more control signals and thereby more outputs to control there is also an opportunity of improve- ments of the dynamics compared to a conventional system. In this paper an approach with LQ-technique is presented for improvements of system dynamics. Since all states in the sys- tem can not be measured a state observer is also considered in the control design. These work present simulations, implementations in a real world forwarder application and results from ve- rifying experiments.
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| 5. |
- Larsson, Felix, 1995-
(författare)
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Evaluation of Aircraft Actuator Technologies
- 2023
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The flight control actuation system is one of the most critical systems in an aircraft. A failure of this system cannot occur, since it would have catastrophic consequences. The environment it operates in is considered as highly demanding, with temperatures ranging from -50 to +60 degrees Celsius, speeds from 0 to Mach 2+ and G-forces from -3 up to 9. At the same time, the system shall be as small and lightweight as possible, since every gram and cm3 will decrease the available payload and/or increase the total aircraft size, which in turn increase the fuel-burn. The preferred choice of technology for actuators has, since the late 1930s, been hydraulics. Hydraulic actuators are characterized by high power density, high technical maturity, high safety, and high response. With emerging benefits from the electric domain, research during the last decade has been focusing on electrified alternatives as the future alternative for actuators. With varying requirements on the actuators depending on the type of air-craft platform, it is not trivial when it is a better alternative to electrify the actuators. For example, with smaller platforms, the forces acting on the actuators will be lower in comparison with larger aircraft. The purpose of this thesis was to investigate if, and when certain technology may be the preferred alternative with regards to size and weight, performance, power consumption and thermal characteristics. Also, it was investigated how to compare different topologies which utilize different technologies, and how certain technology may affect the requirements of surrounding systems in the platform. This work has led to three different approaches for comparison and evaluation of actuator technology that can be applied in early conceptual design of aircraft platforms. The first approach can be used to ensure comparability of the topologies to be studied. The second approach focuses on modeling of performance and thermal impact and can be applied to study static and dynamic behavior of different technologies. The third approach can be used to study how size and weight of actuators will be affected by operational requirements, with special emphasis on high-level modeling with few inputs.
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| 6. |
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| 7. |
- Rösth, Marcus, 1974-
(författare)
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Hydraulic power steering in passenger cars : analysis, modeling and new functionality
- 2003
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- THIS THESIS COVERS various aspects of hydraulic power assisted steering, HPAS, systems in road vehicles. Power steering is viewed as a dynamic system and is investigated with linear and non-linear modeling techniques.With the help of the linear model, relevant transfer functions and the underlying control structure of the conventional power steering system have been derived and analyzed. The non-linear model has been used in concept validation of a new feature that can be added to traditional power steering units in order to increase functionality. This model also has the capability of co-simulation with a vehicle model in order to create realistic tie-rod loads to the power steering model.This thesis treats energy aspects of power steering systems. In order to point out solutions to energy problems, different methods of reducing energy consumption are discussed.The interest for including more functions in power steering systems in road vehicles has increased with the development of new active safety features such as Lane Keep Assist, LKA. The traditional HPAS system cannot meet these new demands, due to the control units pure hydro-mechanical solution. The Active Pinion concept is presented in this thesis, which is a novel concept for controlling the steering wheel torque for future active safety applications. The concept introduces an additional degree of freedom in the control unit. Active safety features are going to play an increasingly important roll in future safety strategies; therefore, it is essential that sub systems, such as power steering systems, in road vehicles are adjusted to meet new demands.
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| 8. |
- Rösth, Marcus, 1974-
(författare)
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Hydraulic Power Steering System Design in Road Vehicles : Analysis, Testing and Enhanced Functionality
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Demands for including more functions such as haptic guiding in power steering systems in road vehicles have increased with requirements on new active safety and comfort systems. Active safety systems, which have been proven to have a positive effect on overall vehicle safety, refer to systems that give the driver assistance in more and less critical situations to avoid accidents. Active safety features are going to play an increasingly important roll in future safety strategies; therefore, it is essential that sub systems in road vehicles, such as power steering systems, are adjusted to meet new demands.The traditional Hydraulic Power Assisted Steering, HPAS, system, cannot meet these new demands, due to the control unit's pure hydro-mechanical solution. The Active Pinion concept presented in this thesis is a novel concept for controlling the steering wheel torque in future active safety and comfort applications. The concept, which can be seen as a modular add-on added to a traditional HPAS system, introduces an additional degree of freedom to the control unit. Different control modes used to meet the demands of new functionality applications are presented and tested in a hardware-in-the-loop test rig.This thesis also covers various aspects of hydraulic power assisted steering systems in road vehicles. Power steering is viewed as a dynamic system and is investigated with linear and non-linear modeling techniques. The valve design in terms of area gradient is essential for the function of the HPAS system; therefore, a method involving optimization has been developed to determine the valve characteristic. The method uses static measurements as a base for calculation and optimization; the results are used in both linear and the non-linear models. With the help of the linear model, relevant transfer functions and the underlying control structure of the power steering system have been derived and analyzed. The non-linear model has been used in concept validation of the Active Pinion. Apart from concept validation and controller design of the active pinion, the models have been roven effective to explain dynamic phenomena related to HPAS systems, such as the chattering phenomena and hydraulic lag.
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| 9. |
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| 10. |
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