| 1. |
- Landberg, Magnus, et al.
(författare)
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THE HYDRAULIC INFINITE LINEAR ACTUATOR APPLIED TO ELEVATORS IN MID-RISE BUILDINGS
- 2018
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Ingår i: PROCEEDINGS OF THE BATH/ASME SYMPOSIUM ON FLUID POWER AND MOTION CONTROL, 2018. - : AMER SOC MECHANICAL ENGINEERS. - 9780791851968
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Konferensbidrag (refereegranskat)abstract
- Hydraulic elevators with conventional long -stroke hydraulic cylinders are limited for use in low-rise buildings, up to five floors, due to low hydraulic stiffness, low natural frequency, low hydraulic pressure and large oil volume. With a new hydraulic actuation technology jointly invented at Linkoping University and SAAB named the Hydraulic Infinite Linear Hydraulic Actuator (HILA), these short -comings for hydraulic actuators can be reduced and hydraulic elevators can be offered for mid rise buildings. The HILA technology provides long strokes, high system pressure, compactness and small chamber volumes. The actuator has a higher stiffness and a higher natural frequency compared to conventional hydraulic cylinders. The higher system pressure allows for an even more compact system design, with lower flow levels and a smaller reservoir. The HILA technology combines two short -stroke cylinders with two engaging and disengaging clamping mechanisms into one actuator with long stroke length. The motion of each single short stroke piston linked together by the clamping mechanisms creates the motion of the piston rod. In this way the two pistons are moving along the rod in a kind of rope climbing motion. The challenge is to implement a control system which can provide a smooth motion without unacceptable jerk at load shift as seen with ordinary directional valves. Earlier research work on HILA technology has shown that a control system with fast servo valves can fulfil these requirements. This study shows promising results from simulation analysis combined with optimization techniques, using slightly modified standard directional hydraulic valves.
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| 2. |
- Landberg, Magnus, et al.
(författare)
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The Hydraulic Infinite Linear Actuator with Multiple Rods
- 2017
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Ingår i: Proceedings of 15:th Scandinavian International Conference on Fluid Power, June 7-9, 2017, Linköping, Sweden. - Linköping : Linköping University Electronic Press. - 9789176853696 ; , s. 279-293
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Future hydraulic actuation systems can be significantly improved by utilisation of a new type of hydraulic linear actuator technology. By enabling multiple actuating elements, integrated in a compact and lightweight single unit controlled by ordinary directional valves it is possible to achieve a high position accuracy. This is a new way to generate and distribute mechanical linear movement and force by using hydraulic actuators in a cost effective way, in less responsive closed loop systems. This is a variant on the Hydraulic Infinite Linear Actuator, HILA, invention. The technology also represents a new sort of digital hydraulics. The presented technology provides typical hydraulic actuator characteristics with high system pressure and potentially no external oil leakage. It is based on a well-known hydraulic clamping element technology used in a new way, where the piston and the piston rod can quickly be coupled and uncoupled by means of the clamping element in a failsafe way by using well defined incremental steps. HILA in its simplest usage, provides new features to hydraulic cylinders such as providing very long strokes, high rod speed, and small chamber volumes which means high stiffness and low capacitance. The aim of this study is to present a fundamentally new way of using hydraulic actuators. The invention is called the Hydraulic Infinite Linear Actuator with Multiple Rods, HILA MR. The study presents the idea, principles and feasible combinations of the technology. Also applications in the aircraft and robotic field will be presented.
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| 3. |
- Strömberg, Jan-Erik, et al.
(författare)
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Complex Hybrid Systems I : a Study of Available Tools and Specification of Planned Work
- 1994
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this report is twofold. First, to provide a common framework and terminology for the participants of the Nutek supported COHSY project a multi-disciplinary academic-industrial cooperation on COmplex Hybrid SYstems. Second, to define more precisely the activities within the nest few years of the project. Therefore, the current report should be considered as a project definition rather than a statement about the constructive work currently in progress.
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| 4. |
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| 5. |
- Degerman, Pär, 1976-, et al.
(författare)
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Hough Transform for Parking Space Estimation Using Long Range Ultrasonic Sensors
- 2006
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Ingår i: SAE Technical Paper. - Detroit : SAE. - 0148-7191. ; , s. 2006-01-0810-
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Konferensbidrag (refereegranskat)abstract
- This paper describes a system for supporting the driver of a passenger car in different parking situations. Todays cars are getting larger in size and the drivers view in both forward and rearward direction is becoming more limited. This fact calls for a system of sensors and algorithms capable of supporting the driver through the parking maneuvre in a safe and smooth way.The paper presents the development of some of the subsystems in a fully automatic parallel parking system, utilizing ultrasonic ranging sensors for environment mapping. In contrast to existing passive parking aid systems, the ultrasonic range sensors need to have a narrower aperture to be able to map the surroundings properly. This can be accomplished by either increased sensor size or by a higher number of sensors.The emphasis of the paper is the signal conditioning in the parking system. The Hough-transform along with a statistical CUSUM test are used to find the properties of the target parking space.The system makes use of hardware components already available in modern cars and a small number of added components. The resulting system is automated, from finding a suitable parking space to maneuvering the car into the parking space, while keeping the driver in authority since the longitudinal control, i.e. throttle and brakes, are still the drivers responsibilities.The prototype system is implemented in a Volvo S60 which has been modified with an electric power steering unit and an ultrasonic sensor array consisting of a total of six sensors spread out around the vehicle. The electric power steering unit is used for steering wheel angle control when the system is active by adding an external torque to the assist torque normally applied.
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| 6. |
- Degerman, Pär, et al.
(författare)
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Ultrasonic Sensor Modeling for Automatic Parallel Parking Systems in Passenger Cars
- 2007
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Ingår i: SAE Technical Paper. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; , s. 2007-01-1103-
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Konferensbidrag (refereegranskat)abstract
- The performance of a parking system is dependent on many factors. One is the placement of the sensors. In this paper a system which uses ultrasonic ranging sensors is considered. The mounting of a ultrasonic sensor on a passenger vehicle is restricted by, among other factors, design, assembly process, enclosure cost and reliability. All of which must be considered when choosing optimal mounting locations.The basis of this work includes a ray-trace based simulation environment which is used to capture the physical properties of sound traveling through air. The simulation environment together with sensor models, is used to evaluate the effect of different mounting positions on the accuracy of the detection of the parking space. The Hough transform is used here, as well as in the real system, in order to extract the confining lines of the parking space from the sensor measurements. The strength of these lines are then used to compare different sensor mounting locations.The created simulation environment differs from other work in this area since it tries to capture the physical properties of the sound waves as opposed to the geometric-only approach. The emitted sound pulse is divided into a large number of rays, each with sound properties tied to them. These rays are then traced through a model of the parking space environment, reflections are calculated and finally the summarized echo into the listening sensor is calculated.The simulation is implemented in 3D Studio MAX which make it relatively easy to create various realistic parking scenarios. An important factor for choosing 3D Studio MAX as the basis of the simulation environment was that it allowed for a new way of modeling ultrasonics using ray-tracing, and at the same time - using the same ray-tracing technology - excellent visualization capabilities.
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| 7. |
- Dell'Amico, Alessandro, et al.
(författare)
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Investigation of a Digital Hydraulic Actuation System on an Excavator Arm
- 2013
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Ingår i: 13th Scandinavian International Conference on Fluid Power. - : Linköping University Electronic Press. - 9789175195728 ; , s. 505-511
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Konferensbidrag (refereegranskat)abstract
- Digital hydraulics is an ongoing trend that offers many interesting advantages and possibilities. Digital refers to that the system output is discrete, e.g. using an on/off valve with only discrete values or a finite amount of flow steps available. The advantages mentioned when compared to analogue systems are better performance, robust and fault tolerant, and amplitude independent bandwidth. On the other side noise and pressure pulsations must be handled, the physical size can be a problem, and the system requires complicated control. When considering control of linear motion, there are mainly two branches, controlling the flow with several parallel connected on/off valves, which generates discrete output flow values, or switching valves, which in theory can generate any mean output flow. The latter only requires one valve for each flow path but the demand for fast valves is very high, while the former requires many valves but avoids high frequent switching. With the introduction of a multi-chamber cylinder, secondary control is now also possible for linear motion. This paper is a first step in the investigation of the system applied to an excavator arm. The cylinder has four chambers, each with different area. Three pressure lines are used and a valve-pack of 27 on/off valves. The valve-pack connects the three pressure lines with each chamber generating 81 available force steps. The scope has been to start out with relative simple control of the velocity of the cylinder. To handle unnecessary switching of valves, different penalty strategies were tested. The results are promising where relatively smooth control could be achieved at the same time challenges with the system were identified. Next step is to investigate the force transients due to different capacitance in all four chambers as well as mode control for better accuracy. Energy potential compared to original system remains to investigate as well.
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| 8. |
- Dell'Amico, Alessandro, et al.
(författare)
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Modeling, Simulation and Experimental Verification of a Solenoid Pressure Control Valve
- 2009
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Konferensbidrag (refereegranskat)abstract
- Simulation is a great tool to help the development of products. For simulation to be a validtool there are high demands on the models, where they need to be accurate and fast, regardingcomputational time. This work is a first step to model and implement a 4 wheel drive system.The system is electronically controlled and the torque transferred by the system is dependenton the pressure built up by the hydraulic system. This work focuses primary on the develop-ment of the solenoid pressure control valve model. In order to perform simulations, the valvemodel needs to be connected to the rest of the system. The supply pressure is provided froma piston accumulator, that is implemented only to provide the right functionality at this stage.The load in this system is composed of a wet multiplate clutch, that is implemented only as astatic model based on measurements. The modeling of the valve was divided into studying theelectromagnetical part and hydromechanical part separately. The electromagnetical part, i.e.the solenoid, is modeled as a resistor in series with a nonlinear inductor. The electromagneticcharacteristics is modeled with the help of a curve fitting technique. A testbench was developedfor this purpose. The simulation results of the solenoid agrees well with measured results. Alinearized analysis of the hydromechanical part was performed in order to better understand thedynamics of the valve and see the most dominant effects. Two valve configurations resultedfrom this work. One includes more dynamics and has the possibility to change more param-eters in order to study different effects. The other configuration was based on the linearizedanalysis and therefore includes only the most dominant dynamics. This model is much fasterto simulate. Both configuration shows accurate results when compared to measurements of thesystem.
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| 9. |
- Hägerlind, E., et al.
(författare)
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Near infrared and skin impedance spectroscopy : a possible support in the diagnostic process of skin tumours in primary health care
- 2015
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Ingår i: Skin research and technology. - : John Wiley & Sons. - 0909-752X .- 1600-0846. ; 21:4, s. 493-499
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Tidskriftsartikel (refereegranskat)abstract
- Background/purpose: The global incidence of skin cancer has increased drastically in recent decades, especially in Australia and Northern Europe. Early detection is crucial for good prognosis and high survival rates. In general, primary care physicians have considerably lower sensitivity and specificity rates for detection of skin cancer, compared to dermatologists. A probable main reason for this is that current diagnostic tools are subjective in nature, and therefore diagnostic skills highly depend on experience. Illustratively, in Sweden, approximately 155500 benign skin lesions are excised unnecessarily every year. An objective instrument, added to the clinical examination, might improve the diagnostic accuracy, and thus promote earlier detection of malignant skin tumours, as well as reduce medical costs associated with unnecessary biopsies and excisions. The general aim of this study was to investigate the usefulness of the combination of near infrared (NIR) and skin impedance spectroscopy as a supportive tool in the diagnosis and evaluation of skin tumours in primary health care.Methods: Near infrared and skin impedance data were collected by performing measurements on suspect malignant, premalignant and benign tumours in the skin of patients seeking primary health care for skin tumour evaluation. The obtained data were analysed using multivariate analysis and compared with the diagnosis received by the conventional diagnostic process.Results: The observed sensitivity and specificity rates were both 100%, when discriminating malignant and premalignant skin tumours from benign skin tumours, and the observed sensitivity and specificity for separating malignant skin tumours from premalignant and benign skin tumours were also 100%, respectively.Conclusion: The results of this study indicate that the NIR and skin impedance spectroscopy may be a useful supportive tool for the general practitioner in the diagnosis and evaluation of skin tumours in primary health care, as a complement to the visual assessment.
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| 10. |
- Jouannet, Christopher, 1974-, et al.
(författare)
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Design process for micro air vehicles
- 2003
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Ingår i: Bristol International UAV systems conference,2003. - Bristol, UK : UAV. - 0862925347
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Konferensbidrag (refereegranskat)abstract
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