Academic literature on the topic 'Pneumatic suspension system'

The static and dynamic properties of a vehicle suspension comprising hydraulic struts interconnected in the roll plane are investigated. The fundamental properties of the interconnected suspension are investigated and compared to those of the unconnected suspensions with and without the anti-roll bar, in terms of load-carrying capacity, suspension rate, roll stiffness as well as damping characteristics. The anti-roll performance of the interconnected suspension is analyzed for excitations encountered during directional manoeuvres. The ride quality performance is evaluated for excitations occurring at tire-road interface. It is concluded that the interconnected hydro-pneumatic suspension with inherent enhanced roll stiffness and damping characteristics can significantly restrict the body roll motion to achieve improved roll stability of a vehicle.

Semi-active and active suspensions can improve both ride comfort and handling compared to passive suspensions. The authors have proposed a suspension comprising a pneumatic system capable of changing the stiffness of the suspension and a semi-active magnetorheological damper capable of controlling the suspension damping. Eight configurations of this magnetorheological/pneumatic suspension result from combining two possible stiffnesses (compliant and stiff) and four possible means of producing damping (constant low, constant high, on-off skyhook control and on-off balance control). The minimization of a cost function, which considers both ride comfort and handling, leads to decision maps which indicate the most appropriate configuration depending on vehicle velocity and two pieces of information about the road: the international roughness index and the curve radius. All this information can be gathered from a GPS system and toggling between set-ups is fast, efficient, and easily done by simply opening or closing pipes in the pneumatic system and modifying the current supply in the magnetorheological dampers. The proposed magnetorheological/pneumatic suspension achieves the same roll angle levels as in a comparable passive vehicle while improving ride comfort by reducing acceleration by up to 30%.

Ambulance suspensions often give a poor ride, which may result in deterioration in the condition of ill or injured patients. Suspension of the ambulance stretcher itself is a lower cost option than a purpose- built ambulance suspension and may offer superior isolation of the patient from road-induced disturbances. This paper describes the development of a pneumatic stretcher suspension offering both pitch and heave isolation. Design and theoretical considerations are outlined, and preliminary performance figures reported. Subsequent parts of this paper will explore the dynamics of the system with pneumatic damping and report on the performance of the prototype suspension for a range of patient masses, damping levels and floor vibration inputs.

Perceived comfort level and ride stability are the two most important factors in the evaluation of suspension system in a mobile vehicle. It is extremely difficult to simultaneously maintain a high standard of vehicle ride, handling and body control in the vehicle by using conventional passive suspension system. However, the use of active suspensions would result in better comforts than the passive ones. This paper presents the design and analysis of a pneumatic friction damper and hydro-pneumatic friction damper. A non-linear quarter car model is developed, which includes pneumatic actuation by pressure regulation. The performance of the proposed model was assessed in terms of level of vibration reduction. Simulations on a prototype model show that the proposed system has good performance and robustness.

Background: Vehicles generally travel on different road conditions, and withstand strong shock and vibration. In order to reduce or isolate the strong shock and vibration, it is necessary to propose and develop a high-performance vehicle suspension system. Objective: This study aims to report a pneumatic artificial muscle bionic kangaroo leg suspension to improve the comfort performance of vehicle suspension system. Methods: In summarizing the existing vehicle suspension systems and analyzing their advantages and disadvantages, this paper introduces a new patent of vehicle suspension system based on the excellent damping and buffering performance of kangaroo leg, A Pneumatic Artificial Muscle Bionic Kangaroo Leg Suspension. According to the biomimetic principle, the pneumatic artificial muscles bionic kangaroo leg suspension with equal bone ratio is constructed on the basis of the kangaroo leg crural index, and two working modes (passive and active modes) are designed for the suspension. Moreover, the working principle of the suspension system is introduced, and the rod system equations for the suspension structure are built up. The characteristic simulation model of this bionic suspension is established in Adams, and the vertical performance is analysed. Results: It is found that the largest deformation happens in the bionic heel spring and the largest angle change occurs in the bionic ankle joint under impulse road excitation, which is similar to the dynamic characteristics of kangaroo leg. Furthermore, the dynamic displacement and the acceleration of the vehicle body are both sharply reduced. Conclusion: The simulation results show that the comfort performance of this bionic suspension is excellent under the impulse road excitation, which indicates the bionic suspension structure is feasible and reasonable to be applied to vehicle suspensions.

HighlightsTractor ride vibrations were evaluated under various conditions according to type of cab suspension.Ride vibrations were measured on flat and bumpy roads using four tractors with different cab suspension types.Tractors with hydro-pneumatic suspension exhibited smaller ride vibrations than tractors with rubber mounts.Semi-active hydro-pneumatic control resulted in smaller ride vibrations than those resulting from passive control.Abstract. In this study, tractor ride vibrations were evaluated under various conditions according to the type of cab suspension, and the effects of different cab support methods on these ride vibrations were determined. Ride vibrations on flat and bumpy roads were measured using four tractors equipped with different cab suspension types and were analyzed based on ISO Standard 2631-1 for human exposure to whole-body vibration. The ride vibration values were evaluated using the weighted root mean square acceleration and fourth-power vibration dose value. The results confirmed that the tractor equipped with semi-active hydro-pneumatic cab suspension at the two rear positions yielded smaller ride vibrations than the tractors with rubber mounts at all four positions. Vibration reduction effects of up to 53.8% and 67.1% were yielded in the flat road test and bumpy road test, respectively. In addition, among the two tractors with hydro-pneumatic cab suspension systems, ride vibrations were reduced by approximately 7.1% in the tractor that used semi-active control as compared to the tractor that used passive control. Keywords: Hydro-pneumatic cab suspension, Ride vibration, Rubber mount, Whole-body vibration.

The pneumatic suspension is used to absorb vibration and provide comfortable labor conditions for transportation vehicle drivers. The cause of increased vibration of the tractor, often, are incorrectly matched elastic-damping characteristics of the cushions of the active suspension system, which can not cope (or cope extremely ineffectively) with fluctuations coming from the external background. Since the realization of an experiment for the dynamic analysis of pneumatic suspension takes a long time, the mathematical models of the vehicle suspension system are used to obtain the response parameters of the pneumatic suspension. In the given article the comparative characteristic of spring’s systems with a cylindrical spring and a linear pneumatic spring as a suspension system is given. To carry out the simulation, the Matlab/Simulink software complex was used, in which, based on the previously obtained values of equivalent rigidity, a simulation of the tractor was built. Since the tractor in this model is considered as a linear system, its spectral function was calculated from the spectrum of the input parameters of the path unevenness and the frequency response of the tractor. These parameters were used to analyze the vibration response of the suspension system to assess the effectiveness of the system and, as a result, assessment of the operator comfort. The algorithm of the proportional integral differentiating (PID) regulation of the suspension system was implemented depending on their output parameters as well. The comparative study shows how the linear model of the pneumatic suspension system controlled by a PID-regulator is able to suppress fluctuations arising from road roughness and whether it is effective than a passive suspension system for a vehicle with a coil spring. The criterion of efficiency in this work was the indicator of the tractor's displacement height.

The nonlinear stiffness and damping properties of the hydro-pneumatic suspension system are introduced, and the nonlinear mathematical model of it is established. Using MATLAB 2009b to establish the computer simulation program and draw out the nonlinear stiffness curve and damping properties curve of the hydro-pneumatic suspension system. Then, researching the influences of related parameters' changes on the nonlinear stiffness and damping properties of the hydro-pneumatic suspension system. The simulation of vehicle dynamic performance research's foundation is provided.

This study is focused on modifying an existing solenoid valve based semi-active hydropneumatic spring-damper system using Magneto-Rheological (MR) fluid. The MR fluid's effective viscosity can be altered by application of a magnetic field. Therefore, using a magnetic/ MR valve makes it possible to change the state of the system by simply changing the applied magnetic field. A prototype MR valve was developed to determine whether a unit small enough for installation was possible. This prototype valve was designed from first principles and properties such as pressure drop over the valve (damping) and flow blocking (for switching between spring characteristics) were measured. The measured pressure drop over the valve was higher than what was design for which was due to an incorrect assumption for the viscosity of the thixotropic MR Fluid. The flow blocking ability of the valve was determined by constant force tests. Results showed that the valve could virtually block the flow of fluid for approximately a quarter of the vehicles weight. With the second prototype, the valve design and magnetic circuit design were improved. Two valves were constructed and implemented on a prototype suspension system. The damping characteristics of the system were lower than expected, however they can be improved by changing the valve geometry. The base spring characteristics are acceptable, however the higher spring characteristics fail when a high force is exerted on the strut that exceeds the valves flow blocking capability. The response time of the valve is not yet sufficient to make the system viable for real world implementation, especially under extreme conditions that can change more rapidly than the current valves.
Dissertation (MEng)--University of Pretoria, 2015.
Mechanical and Aeronautical Engineering
MEng
Unrestricted

This report details the work done in a master thesis project. The project was conducted at the Brake Performance Department at Scania CV AB. The project involves the development of a numerical model (in Matlab) that calculates and predicts air consumption in a truck under different drive cycles. The report first details tests and experiments done so as to acquire the necessary information for the development of the model. The report then presents the model that was created and delves into tests that were conducted for its validation. A model is created that allows the user to select different component combinations on the trucks along with different loading scenarios and drive cycles. Finally the model is used to evaluate air consumption in trucks during particularly strenuous cycles. The model developed is found to be reliable and accurate to with 7% with regard to amount of air consumed. With its help, several recommendations on how air consumption in commercial vehicles can be improved are made. The best components’ combination is also found and presented.
I denna rapport beskrivs ett examensarbete som genomfördes på bromsavdelningen på Scania CV AB. Projektet innefattar utveckling av en numerisk modell (i Matlab) som beräknar och förutspår luftförbrukningen i en lastbil under olika körcykler. I rapporten beskrivs det tester och experiment som gjordes för att ta fram nödvändiga uppgifter för utvecklingen av modellen. Sedan presenteras modellen som skapades och alla valideringstester som genomfördes. Modellen är gjord så att användaren kan kombinera olika komponentkombinationer för lastbilar med olika lastningskonfigurationer och körcykler. Slutligen används modellen för att utvärdera luftförbrukningen i lastbilar under särskilt ansträngande körcykler. Den utvecklade modellen visade sig vara pålitlig och korrekt med en felmarginal på 7% med avseende på mängden luft som konsumeras. Med dess hjälp kunde flera rekommendationer ges om hur luftförbrukningen i kommersiella fordon kan förbättras. De bästa komponentkombinationerna hittades också och presenteras i denna rapport

Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.22.02 – автомобілі та трактори. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2019 р. Дисертація присвячена поліпшенню експлуатаційних властивостей колісного трактора в агрегаті з напівпричепом при русі на транспортних режимах за рахунок обладнання переднього моста комбінованою пневморесорною підвіскою та визначення її раціональних параметрів. Для вирішення поставленої задачі в роботі проаналізовані сучасні тенденції використання колісних тракторів під час перевезення вантажів, котрі є основною сільськогосподарською продукцією, а також продукцією призначеною для забезпечення виробничих процесів сільськогосподарських підприємств. Визначено основні вимоги, які висуваються до конструкції тракторів, які застосовуються в якості транспорту в сільськогосподарській галузі. Розглянуто тенденції розвитку конструкцій систем підресорювання колісних тракторів з урахуванням виконання вантажоперевезень із підвищеними транспортними швидкостями. Виконано аналіз методів і конструктивних засобів поліпшення плавності ходу й зниження динамічної навантаженості ходових систем. Визначено експлуатаційні вимоги, які висуваються до підвісок колісних тракторів. А також встановлені шляхи поліпшення показників плавності ходу на основі вдосконалення систем підресорювання. У рамках дослідження складена узагальнена математична модель поздовжньо-кутових, вертикальних і поздовжніх коливань машино-тракторного агрегату на базі колісного трактора з напівпричепом, яка дозволяє досліджувати плавність ходу й динамічну навантаженість ходової системи. Складена математична модель доповнена математичними моделями пневматичної шини, пневматичного гумово-кордового пружного елемента й тяглово-зчіпного пристрою. Це дозволяє врахувати наявність демпфірування в пневматичній системі комбінованої пневморесорної підвіски, найбільш повно оцінити вплив нелінійності пружних і дисипативних характеристик шини та пневмобалона, а так само наявність зазору в тяглово-зчіпному пристрої на показники плавності ходу й динамічну навантаженість ходової системи колісного трактора. Для найбільш повної оцінки плавності ходу й динамічної навантаженості ходової системи колісного трактора обладнаного різними типами систем підресорювання математична модель реалізована в детермінованій постановці з мікропрофілем, який відповідає різним дорожнім покриттям. Для зниження динамічної навантаженості ходової системи й поліпшення параметрів плавності ходу машино-тракторного агрегату на базі колісного трактора та напівпричепа, була розроблена комбінована пневморесорна підвіска, яка встановлена на передній міст трактора. При розробці регульованої пневморесорної підвіски використовувалися серійні вузли та деталі підвіски з листовими металевими ресорами. Пневморесорна підвіска розміщена в габаритних розмірах серійної підвіски, та складається з листових металевих ресор й двохсекційних пневмобалонів з додатковими повітряними резервуарами. Для збільшення демпфування в підвісці, в трубопроводі на вході до додаткових резервуарів було встановлено дроселі. При зростанні статичного навантаження на передній міст регулятор положення рами за допомогою клапану автоматично забезпечує надходження стисненого повітря до пневмобалонів по трубопроводах, а при її зменшені – випуск повітря до атмосфери. Таким чином забезпечується підтримання постійного зазору між пружним упором стискання та переднім мостом. З метою найбільш повної оцінки властивості конструкції розробленої пневморесорної підвіски та її досконалості при використанні трактора проведено експериментальні дослідження машино-тракторного агрегату в різних експлуатаційних умовах. Результати отримані під час проведення натурного експерименту дали можливість підтвердити достовірність теоретичних досліджень, та оцінити адекватність математичної моделі використовуваної для вивчення взаємозв’язків між параметрами конструкції підвіски та її експлуатаційними показниками. Також була запропонована методика проведення експериментальних досліджень по визначенню демпфування в пневматичній системі комбінованої пневморесорної підвіски, методика визначення параметрів плавності ходу та динамічної навантаженості ходової системи машино-тракторного агрегату при виконанні транспортних робіт. Під час проведення натурного експерименту визначено ступень дисипації в пневморесорній підвісці при різних прохідних перетинах дроселя, а також при різних об’ємах додаткових резервуарів, та визначено раціональний діаметр перехідного перетину дроселя. Проведена оцінка плавності ходу та динамічної навантаженості ходової системи машино-тракторного агрегату обладнаного серійною ресорною підвіскою, комбінованою пневморесорною підвіскою з гідравлічними амортизаторами та без гідравлічних амортизаторів, при русі трактора по дорозі з асфальтним і ґрунтовим покриттям, а саме проведена порівняльна оцінка пневматичного й гідравлічного демпфірування, порівняльна оцінка плавності ходу трактора із серійною та пневморесорними підвісками, шляхом визначення параметрів низькочастотних коливань у характерних точках трактора. Також визначена динамічна навантаженість ходової системи трактора оснащеного різними системами підресорювання. Для вимірів результатів експерименту, а саме для реєстрації параметрів низькочастотних коливань використовувався вимірювальний комплекс, що складається з вібровимірювальної апаратури. Для реєстрації динамічного навантаження передніх й задніх коліс трактора використовувалися тензодатчики, наклеєні на рукавах мостів, при цьому тензометричні датчики збиралися в тензометричні мости сигнал з котрих надходив до фіксуючої апаратури. На підставі аналізу отриманих даних встановлено, що застосування комбінованої пневморесорної підвіски з гідравлічними амортизаторами в порівнянні із серійною ресорною підвіскою дозволяє знизити величини середньоквадратичних прискорень у характерних точках трактора й знизити динамічне навантаження, що діє на колеса машино-тракторного агрегату. Проведено теоретичні дослідження, які дозволили дати об'єктивну оцінку впливу типу підвіски та її конструктивних параметрів на плавність ходу й динамічну навантаженість ходової системи колісного трактора. Визначено шляхи вдосконалення системи підресорювання й розроблені рекомендації з вибору раціональних параметрів підвіски. На підставі аналізу проведених експериментальних досліджень динамічних процесів, які виникають під час руху колісного трактора в агрегаті з напівпричепом, встановлено, що результати теоретичних розрахунків якісно й кількісно відображають характер зміни та рівень показників плавності ходу й динамічної навантаженості ходової системи машино-тракторного агрегату. Також підтверджені рекомендації щодо обраних раціональних параметрів системи підресорювання переднього мосту колісного трактора. Згідно рекомендацій найкращі показники плавності ходу та динамічної навантаженості ходової системи колісного трактора з шарнірно-зчленованою рамою на транспортних роботах досягаються при наступних обґрунтованих основних конструктивних параметрах комбінованої пневморесорної підвіски: діаметр прохідного перетину дроселя 9 мм, що забезпечує максимальне повітряне демпфірування в пневматичній системі та коефіцієнт загасання ψ=0,21; об’єм додаткових резервуарів Vd =40·10ˉ³ м³ на сторону; тиск у пневматичній системі 0,27 МПа; величина коефіцієнта загасання гідравлічного амортизатора ψа=0,21.
The dissertation for obtaining a scientific degree of Candidate of Science (Technology) on the specialty 05.22.02 – automobiles and tractors. –National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2019. The dissertation is devoted to improving the operational properties of a wheeled tractor in an aggregate with a semi-trailer during the driving in transport modes, due to the equipment of the front axle with a combined air spring suspension and determining its rational parameters. To solve this problem we have analyzed the current tendencies in the application of wheeled tractors in the transportation of the main agricultural products, as well as products intended to support the production processes of agricultural enterprises. The basic requirements for the construction of tractors used as a transport in the agricultural sector have been defined. The tendencies of development of designs of suspension systems of wheel tractors with consideration of performance of cargo transportation with the increased transport speeds have been considered. The analysis of methods and constructive approaches of improving the smoothness of the course and reducing the dynamic load of the running systems have been performed. The operational requirements for suspension wheeled tractors have been defined. There are also ways to improve the smoothness of the course based on the improvement of the suspension systems. In the framework of the study a generalized mathematical model of longitudinal-angular, vertical and longitudinal oscillations of a machine-tractor unit based on a wheeled tractor with a semi-trailer, which allows to investigate the smooth running and the dynamic load of the running system, is drawn up. The mathematical model is completed with mathematical models of pneumatic tire, pneumatic rubber-cord elastic element and traction coupling. This allows to take into account the presence of damping in the pneumatic system of the combined pneumatic spring suspension, to fully assess the influence of nonlinearity of the elastic and dissipative characteristics of the tire and the pneumatic cylinder, as well as the presence of a gap in the traction-coupling device on the trajectory of smooth running and dynamic load. For the most completed evaluation of the smooth running and dynamic loading of the running system of a wheeled tractor equipped with different types of suspension systems, a mathematical model is implemented in a deterministic formulation with micro-profiles corresponding to different road surfaces. To reduce the dynamic load of the running system and improve the parameters of the smooth running of the machine-tractor unit based on the wheeled tractor and semi-trailer, a combined pneumatic spring suspension have been developed, which was mounted on the front axle of the tractor. Developing the adjustable pneumatic spring suspension we used serial units and suspension parts with sheet metal springs. The pneumatic spring suspension is housed in the overall dimensions of the serial suspension, and consists of sheet metal springs and two-section pneumatic cylinders with additional air tanks. In order to increase the damping in the suspension, throttles were installed in the pipeline at the inlet to the additional tanks. As the static load on the front axle increases, the regulator of the frame position by means of a valve automatically ensures the supply of compressed air to the air cylinders through the pipelines, and with its reduction – the release of air to the atmosphere. This ensures that there is a constant gap between the elastic compression stop and the front axle. With the purpose of the most complete evaluation of the design properties of the developed pneumatic spring suspension and its perfection when using the tractor, experimental studies of the machine-tractor unit under different operating conditions have been performed. The results obtained during the full-scale experiment made it possible to confirm the validity of theoretical studies and to evaluate the adequacy of the mathematical model used to study the relationship between the suspension structure parameters and its performance. Also, a method of conducting experimental studies to determine the damping in the pneumatic system of the combined pneumatic spring suspension, the method of determining the parameters of smooth running and the dynamic load of the running system of the machine-tractor unit in the performance of transport works was also proposed. During the full-scale experiment, the degree of dissipation in the pneumatic spring suspension was determined at different throttle cross-sections, as well as at different volumes of additional tanks, and the rational diameter of the throttle cross-section was determined. The estimation of the smoothness of the course and the dynamic loading of the running system of the machine-tractor unit equipped with a serial spring suspension, combined pneumatic spring suspension with hydraulic shock absorbers and without hydraulic shock absorbers, when driving the tractor on the road with asphalt comparative estimation of the smooth running of the tractor with serial and pneumatic spring suspensions, by determining the parameters of low-frequency oscillations at the characteristic points of the tractor. The dynamic loading of the running gear of the tractor equipped with various suspension systems is also determined. To estimate the results of the experiment, namely to record the parameters of low-frequency oscillations, a measuring complex consisting of vibration measuring equipment was used. To register the dynamic load of the front and rear wheels of the tractor were used strain gauges glued to the sleeves of the bridges, while the strain gauge sensors were collected in the strain gauge bridges signal from which came to the fixing equipment. Being based on the analysis of the obtained data, it has been found out that the application of a combined pneumatic spring suspension with hydraulic shock absorbers in comparison with the serial spring suspension allows to reduce the magnitude of the rms acceleration at the characteristic points of the tractor and to reduce the dynamic load acting on the wheels of the machine-tractor. Theoretical researches allowed to give an objective estimation of influence of a type of a suspension bracket and its design parameters on smoothness of a course and dynamic loading of a running system of a wheel tractor are carried out. Ways to improve the suspension system were identified and recommendations were made for choosing rational suspension parameters. Based on the analysis of the experimental studies of the dynamic processes that occur during the movement of a wheeled tractor in a semi-trailer unit, it is established that the results of theoretical calculations qualitatively and quantitatively reflect the nature of the change and the level of smoothness and dynamic load of the running gear of the machine-tractor system. Recommendations for the selected rational parameters of the front axle suspension system of the wheeled tractor have been also confirmed. According to the recommendations, the best performance of smooth running and dynamic loading of the running system of the wheeled tractor with the articulated frame on the transport works are achieved with the following substantiated basic design parameters of the combined pneumatic spring suspension: diameter of the throttle cross-section 9 mm, which provides the maximum air damping in the pneumatic system and attenuation coefficient ψ=0,21; volume of additional tanks Vd =40·10ˉ³ m³ per side; pressure in the pneumatic system 0,27 MPa; the value of the damping coefficient of the hydraulic shock absorber ψа=0,21.

Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.22.02 – автомобілі та трактори. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2019 р. Дисертація присвячена поліпшенню експлуатаційних властивостей колісного трактора в агрегаті з напівпричепом при русі на транспортних режимах за рахунок обладнання переднього моста комбінованою пневморесорною підвіскою та визначення її раціональних параметрів. Складено узагальнену математичну модель поздовжньо-кутових, вертикальних та поздовжніх коливань машино-тракторного агрегату на базі колісного трактора в агрегаті з напівпричепом, яка дає змогу дослідити плавність ходу та динамічну навантаженість ходової системи з урахуванням нелінійності пружних та дисипативних характеристик підвіски, а також конструктивних характеристик тягово-зчіпного пристрою. Виконано теоретичні дослідження, котрі дозволили дати об'єктивну оцінку впливу типу підвіски та її конструктивних параметрів на плавність ходу й динамічну навантаженість ходової системи колісного трактора. Визначено шляхи вдосконалювання системи підресорювання та її раціональні параметри. На основі експериментальних досліджень підтверджено достовірність математичної моделі руху машино-тракторного агрегату на транспортних швидкостях, та підтверджено рекомендації щодо вибраних раціональних параметрів системи підресорювання переднього моста колісного трактора.
The dissertation for obtaining a scientific degree of Candidate of Science (Technology) on the specialty 05.22.02 – automobiles and tractors. –National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2019. The dissertation is devoted to improving the operational properties of a wheeled tractor in an aggregate with a semi-trailer when driving in transport modes, due to the equipment of the front axle with a combined air spring suspension and determining its rational parameters. A generalized mathematical model of the longitudinal-angular, vertical and longitudinal oscillations of a machine-tractor unit based on a wheeled tractor in an aggregate with a semi-trailer has been compiled, which allows us to study the smoothness and dynamic loading of the running system with taking into account the nonlinearity of the elastic and dissipative characteristics of the suspension, as well as the structural characteristics of the towing device. Theoretical studies have been carried out, which made it possible to give an objective assessment of the influence of the type of suspension and its design parameters on the smoothness and dynamic loading of the wheeled tractor running system. Ways to improve the suspension system are identified and recommendations for the selection of rational suspension parameters are developed. Based on experimental studies, the reliability of the mathematical model of the movement of a ma-chine-tractor unit at transport speeds is confirmed. The recommendations regarding the selected rational parameters of the suspension system of the front axle of the wheeled tractor are also confirmed.

This thesis describes a programme of work which has been undertaken with the objective of obtaining data relating to the performance of on-line mass flow rate meters as applied to pulverised coal injection systems. Such injection systems are utilised widely in power generation, cement and steel manufacture. A technology review was carried out, incorporating an extensive literature survey. This review precipitated the conclusion that a number of techniques have been proposed, which may be applicable to the measurement under investigation. However, very little experimental verification of sensing systems based on these techniques had been undertaken. A test facility, suitable for such verification was therefore developed and an extensive programme of tests were carried out, of a sensing system based on an electrostatic technique. The development of a mathematical model of the sensor operation has also been undertaken, in an attempt to explain some of the more unusual aspects of the experimental results. The overall conclusion is that some aspects of the measurement can be achieved without major difficulties, whilst problems have yet to be resolved in respect of other aspects of the measurement system. The principle of the measurement system is such that the independent measurement of average particle velocity and suspension density are required in order to measure mass flow rate. The measurement of average particle velocity was shown to be achievable by either of two techniques, whilst the measurement of suspension density proved more problematic. Recommendations for further work, aimed at addressing these remaining aspects are detailed.

Tato práce se se zabývá návrhem kinematiky zavěšení kol obou náprav. Na základě analýz jízdních dat, multi-body simulací v softwaru Adams Car, simulací v Matlabu a analytických kalkulací v Mathcadu, je navržena řada změn s cílem zlepšit jízdní vlastnosti vozu Formule student, tyto změny jsou následně implementovány do CAD modelu vozu. Jednotlivé změny kinematiky náprav jsou provedeny na základě analýzy konkrétního problému, který se snaží řešit. Jednou z problematik je zástavbová náročnost systému odpružení a zavěšení zadních kol, zde je cílem snížit hmotnost, výšku těžiště a moment setrvačnosti. Další problematikou je geometrie předního kola, kde je cílem zlepšit využití pneumatik a snížit síly v řízení. Dále se práce zabývá simulacemi elastokinematiky zadní nápravy, součástí je také návrh měřícího zařízení. V poslední části je zkoumán vliv provedených změn i elastokinematiky na jízdní dynamiku vozu v ustálených stavech za pomocí MM metody simulované s modelem celého vozu v Adams Car a zpracované v Matlabu.

碩士
大葉大學
機械工程研究所碩士在職專班
96
A heavy off-road land vehicle’s safety, ride, and handling are the mainly consideration when exercised in cross-country road. Since the traditional mechanical suspension system need to maintain controllable of vehicle, the driver and passengers have to endure the intense impact from the road. On the other hand, the pursuit of ride will be ignored by safety and handling. To explore a good suspension system installation is very important. This paper adopted hydro-pneumatic suspension system and used double A-arm suspension design institutions to discuss heavy-duty wheeled vehicle. And, this paper utilized Automatic Dynamic of Mechanical Systems (ADAMS), a kind of software for multi-body dynamics, to establish a two-degree-of-freedom (2-DOF) quarter-car dynamic model. Then, input a different frequency stability sine wave to carry observation of the quality of dynamic response, to examine the vertical movement and the frequency domain performance of the hydro-pneumatic suspension system, and to explore the human body vibration on the impact of comfort. Re-use suspension durability testing platform for dynamic experiments, comparison of the vertical movement and acceleration between the actual hydro-pneumatic suspension system components and construction model. Finally, implementation of decompression tests for the nonlinear air-spring of the hydro-pneumatic suspension system, to understand suspension system performance by the pressure of air- spring changes impact. The results showed that the heavy-duty wheeled vehicle using hydro-pneumatic suspension system can reduce the components occupy space of vehicles and perform a more stable condition. It can achieve good results in ride evaluation. In addition, the experimental verification of results of the hydro-pneumatic suspension system ADAMS model is very close to the actual status. Compared with the traditional coil-spring suspension system, the hydro-pneumatic suspension system can reduce the pressure of air-spring to improve riding comfort. The hydro-pneumatic suspension system in this research can be applied in the heavy type vehicles, and it can assemble with semi-active or active control components to increase the suspension performance. The hydro-pneumatic suspension system ADAMS model can expand to whole vehicle modeling, and further forecast the performance of ride comfort and handling.

碩士
國立臺灣大學
機械工程學研究所
103
This thesis studies the dynamic and structural analysis of the hydro-pneumatic suspension of the wheeled heavy vehicle, and discussion on the performance of the new hydro-pneumatic shock absorber and the structural strength and rigidity of new design components of the suspension. From literature review, this study summarizes conventional methods in research of the suspension system, and chooses suitable simulation methods for research. In addition to the rigid body model commonly used in the literature, this study creates a flexible body model that is closer to real suspension components to obtain more realistic results, and discusses on the differences in the results between rigid body model and flexible body model. This thesis uses finite element software: Abaqus to create rigid body model simulation analysis, and uses multi-body dynamic software: ADAMS to do the same simulation, and compare results between Abaqus and ADAMS. Finally, this study uses Abaqus to create the flexible body model to obtain more realistic results. The simulation results show that dynamic results between Abaqus and ADAMS are consistent, and it means the rigid model and its results are reasonable. From results of the flexible body model, it shows the newly designed hydro-pneumatic shock absorber doesn’t meet requirements. And the structural strength and rigidity of new design components of the suspension are enough. Finally, by comparing the results between rigid body model and flexible body model, this thesis presents a more efficient method of dynamic and structural analysis, and uses this method to simulate suspension responses with different parameters to provide the basis for improving performances of the shock absorber.

碩士
輔仁大學
電機工程學系碩士班
104
This thesis firstly proposed a pneumatic road actuation system based on fuzzy logic control technique for the developed suspension test bench. The road actuation system can provide the simulated road profile for the analysis in the vehicle suspension control system. Further, the neural network (NN) is applied to learn the control parameters of fuzzy logic controller in different road surface conditions. Due to high nonlinearity and uncertainty of the utilized pneumatic actuation system in the developed road surface simulator, the genetic algorithm (GA) optimization is adopted to assist NN to gain the optimized control parameters for the fuzzy controller. In the second part of thesis, LQR-based optimal controller is designed for the pneumatic-muscle active vehicle suspension system against the road disturbance. Besides, the road profile is employed into the feedforward compensation with the vehicle body control loop so that the suspension control performance can be enhanced. Finally, the experimental results under different road conditions are given to verify the superior performance of the active suspension controller using pneumatic muscle actuators.

碩士
龍華科技大學
機械工程系碩士班
104
This thesis aims at the controller design for the pneumatic muscle activate vehicle suspension system in order to provide better riding comfort and driving controllability. Since the pneumatic muscle activate vehicle suspension system is highly nonlinear and time-dependent, it is difficult to build an accurate mathematical model for the system dynamics of the controller design. Therefore, this thesis combines a finite Fourier series approximation system dynamic mathematical model with adaptive control, sliding mode control, and the H_∞ tracking technique to design an adaptive sliding mode controller for a pneumatic muscle activate vehicle suspension system. The controller consists of Fourier series and an adaptive control approximation system dynamic mathematical model, where the sliding mode controller design requires the constraints of the system’s mathematics model. In addition, the H_∞ tracking technique is applied to compensate the approximation error and system external interference, in order to mitigate the discontinuous jump cut caused by the sliding mode controller, and the updated rules of the controller parameters are deduced from the Lyapunov stability criteria, thus, guaranteeing the stability of the controlled process of the system, improving the control effect, and reducing the difficulty level of actual control. Furthermore, in order to enhance the vibration suppression and vibration reduction of the system, this thesis uses the grey forecast algorithm to predict the next system error as the controller input. The experiments prove that the proposed controller with the grey forecast algorithm performs better vibration suppression and vibration reduction effects on various pavements.

This chapter discusses vibration isolation of STM and AFM. First, the basic concepts of vibration isolation are illustrated by a one-dimensional system using elementary mechanics. The source of vibration, the environmental vibration, its characteristics, and methods of measurement are presented. The importance of vibration isolation at the laboratory foundation level and the proper mechanical design of STM and AFM are then discussed. The focus of this chapter in on the most important vibration isolation system: two-stage suspension spring with eddy-current damping. A detailed analysis of the two-stage spring system as well as aspects of practical design is presented. The principles and design charts for eddy-current damping system are discussed. Finally, the commercial pneumatic vibration isolation system is briefly discussed.

The paper presents implementation of a modified skyhook control on a purely pneumatic suspension system comprising of an airspring, a pressure-differential causing geometry such as a sharp edged orifice and an accumulator, which utilizes the dynamics of compressible air flow through an orifice to inject damping into the suspension rather than heat dissipation as in suspensions with oil-base damper. A continuous-skyhook logic is implemented on the hardware built as a single degree of freedom system. For a head-to-head comparison, a contemporary semi-active suspension using an MR-damper is modeled. The airspring of this suspension is modeled from first principles of Thermodynamics and a new continuously differentiable function describing the force-velocity profiles of the MR-damper is developed. An evaluation of the sprung mass acceleration shows that the performance of the pneumatic suspension rivals that of the MR based unit for an arbitrarily chosen base excitation input. The modified Skyhook law proposed for producing pneumatic damping is shown to be able to inject sufficient damping (compared to MR-Damper), thereby off-setting the need for an additional oil damper.

This paper presents analytical modeling, system identification, and controller design for a “pneumatic-only” vibration isolation system. There exist extensive literature on traditional suspension designs but the literature on purely pneumatic suspension devices is very sparse. This paper presents an extensive modeling and experimental work for characterizing dynamical behavior of the system. The experimental data was used to derive approximate but simple low-order dynamic models using system identification techniques. A solenoid operated orifice mechanism is used to control the flow of air mass between air spring and accumulator. The design of accumulated air spring with controlled orifice constitutes a Continuously Variable Natural Frequency and Damping (CVNFD) device introduced in previous work by the second author. The paper also presents a robust control analysis and design for disturbance rejection problem. The results show promising trends for potential use of such simple and inexpensive system in various vibration isolation applications.

Present within the medical literature are numerous studies which indicate the negative effects of the vibration environment encountered by a wheelchair passenger with regard to human health and comfort (Wolf, Cooper, Pearlman, Fitzgerald, & Kelleher, 2007). In the regard, the accelerations due to road variations have been documented to cause numerous health effects in the human body, such as chronic back, increased need for medication and painkillers, and aggravation of the primary disease, thereby illustrating a need for improvement of the vibration environment (Weisman & Huston, 1995). The current state of the art for wheelchair suspensions is very basic with vast majority of wheelchairs having no suspension of any kind (Cooper, Wolf, Fitzgerald, Bonninger, Ulerich, & Ammer, 2003), some that do offer suspensions use simple off-the-shelf components and are not tuned, reducing performance (Wolf, Cooper, Pearlman, Fitzgerald, & Kelleher, 2007) (Hostens, Papaioannou, Spaepen, & Ramon, 2003). This research study was conducted to design and implement a new semi-active suspension system utilizing the combination of purely pneumatic system components comprising of an airspring and an electronically controlled, high-fidelity, electro-mechanical valve to achieve variable pneumatic damping in real time. Three semi-active controller types were designed and tested in this research, viz. Skyhook control, Acceleration driven damping control, and a combined control law using a time domain frequency selector to determine which of the above two laws to choose at any given instant. The evaluation of the vibration environment was analyzed with respect ISO 2631, in order assess the performance of each controller. The three controllers were tested and implemented on the hardware. It was noticed that each of the three semi-active suspensions utilizing the different controllers showed a distinct improvement in the ride quality over the basic wheelchair configurations (Wheelchairs with no suspension) that are widely used. Furthermore, each controller design outperformed the passive suspension (current state-of-the-art) by two orders of magnitude. It was also shown that implementation of a passive suspension was counter-productive to system performance.

Hydro-pneumatic suspension and multi-bridges steering system, which can meet the demands of ride comfort and steering maneuverability of the crane by their excellent nonlinear stiffness and damping characteristics and innovative control technology in their electro-hydraulic rear axle steering system, is used for construction industry vehicles widely. Such systems have great influences on controllability, steering stability, driving comfort and safety of a vehicle. Such a complex system includes mechanical multi-body, hydraulic, and control components which are influenced each other. However, few previous works concerned the coupling effects from multidisciplinary view, in general just single domain detail model are built and studied. This paper presents a detailed 5 axle all-terrain crane with hydro-pneumatic suspension and multi-bridges steering system consisting of the mechanical parts of suspension and steering multi-body model with ADAMS, suspension and steering hydraulic model that contain cylinder, control valve, and hydraulic pipes, etc., and the control strategy are built with AMESim software. A co-simulation is carried out to study the handling and stability of the vehicle affected by the hydro-pneumatic suspension and electro-hydraulic steering system. Some typical handling maneuvers, such as cornering steering releasing test and pylon slalom course of test are carried out by co-simulation to evaluate the control strategy of the steering and hydro-pneumatic suspension performance numerically. Comparisons between measured data and simulation results validate the correctness of the model.

The Vehicle Dynamics Group (VDG) at the University of Pretoria has developed a semi-active hydro-pneumatic suspension system for an off road vehicle. The suspension system can switch its characteristics between two discrete spring characteristics as well as two discrete damping characteristics all incorporated in a single suspension strut. This original 4-State Semi-active Suspension System (or 4S4), switches between discrete characteristics through the control a set of solenoid valves. Recently, the 4S4 was further developed with the aim of extending its damping characteristics to be continuously variable through the use of Magneto-rheological (MR) technology. The newly developed MR4S4 prototype received a re-designed flow path which channels the MR suspension fluid through two independent magnetic valves (flow orifice enclosed by coils) in parallel. The damping characteristics of each of the valves are controlled independently by the application of electric currents through damper coils. These valves are also able to block flow completely to achieve the discrete spring characteristics through switching flow to the independent accumulators. However, in order to ensure that this new technology could be effectively applied and controlled a model of the MR4S4 needed to be developed. This paper describes the development and validation of a physics based model which is able to capture the overall dynamics and properties of the MR4S4 suspension system. Importantly, the aim of the research was to appropriately capture the physical properties of both the gas as well as the MR fluid as it interacts with the suspension displacements and forces. This model would aid further research in the development of control strategies and provide insight through simulation studies on the systems’ influence on vehicle dynamics.