Este trabalho apresenta a aplicação da teoria de Controle Robusto H-infinito em modelo não linear de sistema de suspensão ativa com Atuador Tubular de Ímã Permanente (ATIP). Os principais objetivos na aplicação dos sistemas ativos de suspensão são a obtenção de melhores níveis de conforto do usuário e dirigibilidade do veículo em relação aos sistemas de suspensão passivo e semi-ativo, e a manutenção dos limites de deslocamento da suspensão. Inicialmente, são apresentados os modelos de suspensão ativa de um quarto de carro e carro completo, utilizados respectivamente como planta para o projeto dos controladores H-infinito e como modelo para as simulações dos sistemas de suspensão em malha fechada. Em seguida, o conjunto de controladores H-infinito e desenvolvido, baseado em especificações de projeto definidas, para posterior avaliação e comparação dos sistemas projetados. Verificações de robustez dos sistemas de suspensão ativos, utilizando-se da Análise-µ como ferramenta de avaliação, são feitas em conjunto com as análises de desempenho de cada sistema. A avaliação de desempenho dos sistemas é realizada tanto no domínio do tempo (avaliando-se angulações, velocidades, acelerações, defexões e energia do sistema) quanto no domínio da frequência (através da análise de densidade espectral de potência, ou Power Spectral Density (PSD), das acelerações verticais do veículo e do esforço de controle do atuador). A excitação do sistema é realizada por meio de distúrbios impostos às posições das rodas, dos tipos determinístico e estocástico, representativos de condições reais da aplicação de um veículo. O conjunto de controladores desenvolvido neste trabalho apresenta resultados satisfatórios para distúrbios de entrada do tipo determinísticos e estocásticos, com ganhos de desempenho dos sistemas de suspensão ativa em relação ao sistema passivo de referência de até 34; 92% para a métrica de avaliação do conforto do usuário, de 17; 23% para a métrica da manutenção da dirigibilidade, e de 43; 48% e 30; 10% para as métricas das acelerações dos ângulos de arfagem e de rolagem da carroceria, respectivamente. / This work presents the application of the H-infinity robust control theory into a non-linear model of active suspension system with a Tubular Permanent Magnet Actuator (TPMA). The main objectives in the application of the active suspension systems are the achievement of greater levels of comfort to the user and of road holding for the vehicle, when compared to the passive and semi-active suspension systems, besides the maintenance of suspension displacement limits. Initially are presented the active suspension models of a quarter-car and of a full-car, used respectively as a plant for the design of the H-infinity controllers and as a model for the simulations of the closed loop suspension systems. In the sequel, the controllers are developed, based on properly defined specifications, for further evaluation and comparison among the systems designed. Robustness verications of the active suspension systems, using the µ-Analysis as assessment tool, are performed together with the performance analysis of each system. The performance evaluation of the systems is performed both in the time domain (assessing angles, speeds, accelerations, dections and the energy of the system) and in the frequency domain (through the analysis of Power Spectral Density (PSD) of vertical accelerations of the vehicle and the control efort of the actuator). The excitation of the system is carried out by means of disturbances imposed to the vertical wheel\'s positions. Those disturbances are of deterministic and stochastic types, which are representatives of real working conditions of the vehicle. The set of controllers developed in this work presents satisfactory results for both deterministic and stochastic input disturbances, with performance gains of the active suspension systems in relation to the passive system of reference up to 34; 92%, 17; 23%, 43; 48% and 30; 10% respectively to the assessment metrics of user comfort, handling maintenance and acceleration of the pitch and roll angles of the chassis.

Ce travail de thèse s’inscrit dans le cadre du rejet adaptatif de perturbations sur des structures de contrôle actif de vibrations. L’objectif était de développer des stratégies de commande adaptatives, pour le rejet actif de perturbations, et de les mettre en œuvre sur des procédés réels se trouvant au sein du département Automatique du laboratoire GIPSA-Lab de Grenoble. En première partie, le rejet de perturbations bande étroites inconnues a été traité en utilisant des lois de commande adaptatives en contre réaction basées sur le principe du modèle interne. Ces lois de commande ont été validées expérimentalement sur une plate-forme de suspension active. En deuxième partie, des algorithmes adaptatifs pour l’atténuation de perturbations bande larges par action anticipatrices « feedforward » ont été proposés, analysés, et testés en pratique sur une structure flexible de contrôle actif de vibrations. / This thesis work is a part of adaptive disturbances rejection on some flexible structures in active vibration control (AVC). The objective was to develop adaptive control strategies for the active disturbances rejection, and to implement them on real process located in the Automatic Control Department of GIPSA-Lab in Grenoble. In the first part, the rejection of unknown narrow-band disturbances (Sinusoidal and multi-sinusoidal) was treated using adaptive control laws in « feedback » based on the internal model principle. These control laws have been validated experimentally on an active suspension platform. In the second part, adaptive algorithms for the minimization of the effects of "broadband" disturbances in "feedforward" have been proposed, analyzed and tested in practice on a flexible structure of active vibration control.

Este trabalho foca o estudo e desenvolvimento de um atuador linear com ímãs permanentes aplicado a sistemas de suspensão ativa, com ênfase em suspensão veicular. Seu desenvolvimento considera aspectos específicos como força, volume, razão força/volume, curso e resposta em frequência. Junto ao estudo teórico desenvolve-se o projeto baseado na simulação paramétrica em elementos finitos que analisa aspectos qualitativos e quantitativos importantes para tomada de decisão do projeto, especificamente na definição de materiais e geometrias. Para servir como ferramenta de análise foi empregada uma modelagem analítica que se mostrou eficiente, pois foi capaz de produzir resultados de forma mais rápida que o método de elementos finitos para avaliar grandezas de interesse como força e densidade de fluxo magnético. Por fim e com base nos aspectos de projeto, foi construído um protótipo que permitiu validar os modelos. Os resultados experimentais e teóricos mostraram boa concordância o que permite concluir que os métodos empregados são eficazes, fornecendo subsídios à aplicação em foco. / This work aims the study and development of a linear actuator with permanent magnets applied to active suspension systems, with emphasis on vehicular suspension. That development takes into account specific features such as force, volume, force per volume ratio, stroke and frequency response. Together with the theoretical study the design of the actuator is carried out based on parametric simulation by means of finite elements which analyses qualitative and quantitative aspects that are important to make the project decision, specifically to define materials and geometry. To suit as an analysis tool it was employed an analytical modelling, which showed to be efficient because it was capable of producing faster results than the finite elements method to evaluate physical quantities of interest such as force and magnetic flux density. Finally and based on project aspects, a prototype was built which allowed to validate all models. Experimental and theoretical results showed a good agreement which led to conclude that the employed methods are efficient, providing subsidies to the studied application.

Este trabalho foca o estudo e desenvolvimento de um atuador linear com ímãs permanentes aplicado a sistemas de suspensão ativa, com ênfase em suspensão veicular. Seu desenvolvimento considera aspectos específicos como força, volume, razão força/volume, curso e resposta em frequência. Junto ao estudo teórico desenvolve-se o projeto baseado na simulação paramétrica em elementos finitos que analisa aspectos qualitativos e quantitativos importantes para tomada de decisão do projeto, especificamente na definição de materiais e geometrias. Para servir como ferramenta de análise foi empregada uma modelagem analítica que se mostrou eficiente, pois foi capaz de produzir resultados de forma mais rápida que o método de elementos finitos para avaliar grandezas de interesse como força e densidade de fluxo magnético. Por fim e com base nos aspectos de projeto, foi construído um protótipo que permitiu validar os modelos. Os resultados experimentais e teóricos mostraram boa concordância o que permite concluir que os métodos empregados são eficazes, fornecendo subsídios à aplicação em foco. / This work aims the study and development of a linear actuator with permanent magnets applied to active suspension systems, with emphasis on vehicular suspension. That development takes into account specific features such as force, volume, force per volume ratio, stroke and frequency response. Together with the theoretical study the design of the actuator is carried out based on parametric simulation by means of finite elements which analyses qualitative and quantitative aspects that are important to make the project decision, specifically to define materials and geometry. To suit as an analysis tool it was employed an analytical modelling, which showed to be efficient because it was capable of producing faster results than the finite elements method to evaluate physical quantities of interest such as force and magnetic flux density. Finally and based on project aspects, a prototype was built which allowed to validate all models. Experimental and theoretical results showed a good agreement which led to conclude that the employed methods are efficient, providing subsidies to the studied application.

Este trabalho foca o estudo e desenvolvimento de um atuador linear com ímãs permanentes aplicado a sistemas de suspensão ativa, com ênfase em suspensão veicular. Seu desenvolvimento considera aspectos específicos como força, volume, razão força/volume, curso e resposta em frequência. Junto ao estudo teórico desenvolve-se o projeto baseado na simulação paramétrica em elementos finitos que analisa aspectos qualitativos e quantitativos importantes para tomada de decisão do projeto, especificamente na definição de materiais e geometrias. Para servir como ferramenta de análise foi empregada uma modelagem analítica que se mostrou eficiente, pois foi capaz de produzir resultados de forma mais rápida que o método de elementos finitos para avaliar grandezas de interesse como força e densidade de fluxo magnético. Por fim e com base nos aspectos de projeto, foi construído um protótipo que permitiu validar os modelos. Os resultados experimentais e teóricos mostraram boa concordância o que permite concluir que os métodos empregados são eficazes, fornecendo subsídios à aplicação em foco. / This work aims the study and development of a linear actuator with permanent magnets applied to active suspension systems, with emphasis on vehicular suspension. That development takes into account specific features such as force, volume, force per volume ratio, stroke and frequency response. Together with the theoretical study the design of the actuator is carried out based on parametric simulation by means of finite elements which analyses qualitative and quantitative aspects that are important to make the project decision, specifically to define materials and geometry. To suit as an analysis tool it was employed an analytical modelling, which showed to be efficient because it was capable of producing faster results than the finite elements method to evaluate physical quantities of interest such as force and magnetic flux density. Finally and based on project aspects, a prototype was built which allowed to validate all models. Experimental and theoretical results showed a good agreement which led to conclude that the employed methods are efficient, providing subsidies to the studied application.

Este trabalho apresenta a aplicação da teoria de Controle Robusto H-infinito em modelo não linear de sistema de suspensão ativa com Atuador Tubular de Ímã Permanente (ATIP). Os principais objetivos na aplicação dos sistemas ativos de suspensão são a obtenção de melhores níveis de conforto do usuário e dirigibilidade do veículo em relação aos sistemas de suspensão passivo e semi-ativo, e a manutenção dos limites de deslocamento da suspensão. Inicialmente, são apresentados os modelos de suspensão ativa de um quarto de carro e carro completo, utilizados respectivamente como planta para o projeto dos controladores H-infinito e como modelo para as simulações dos sistemas de suspensão em malha fechada. Em seguida, o conjunto de controladores H-infinito e desenvolvido, baseado em especificações de projeto definidas, para posterior avaliação e comparação dos sistemas projetados. Verificações de robustez dos sistemas de suspensão ativos, utilizando-se da Análise-µ como ferramenta de avaliação, são feitas em conjunto com as análises de desempenho de cada sistema. A avaliação de desempenho dos sistemas é realizada tanto no domínio do tempo (avaliando-se angulações, velocidades, acelerações, defexões e energia do sistema) quanto no domínio da frequência (através da análise de densidade espectral de potência, ou Power Spectral Density (PSD), das acelerações verticais do veículo e do esforço de controle do atuador). A excitação do sistema é realizada por meio de distúrbios impostos às posições das rodas, dos tipos determinístico e estocástico, representativos de condições reais da aplicação de um veículo. O conjunto de controladores desenvolvido neste trabalho apresenta resultados satisfatórios para distúrbios de entrada do tipo determinísticos e estocásticos, com ganhos de desempenho dos sistemas de suspensão ativa em relação ao sistema passivo de referência de até 34; 92% para a métrica de avaliação do conforto do usuário, de 17; 23% para a métrica da manutenção da dirigibilidade, e de 43; 48% e 30; 10% para as métricas das acelerações dos ângulos de arfagem e de rolagem da carroceria, respectivamente. / This work presents the application of the H-infinity robust control theory into a non-linear model of active suspension system with a Tubular Permanent Magnet Actuator (TPMA). The main objectives in the application of the active suspension systems are the achievement of greater levels of comfort to the user and of road holding for the vehicle, when compared to the passive and semi-active suspension systems, besides the maintenance of suspension displacement limits. Initially are presented the active suspension models of a quarter-car and of a full-car, used respectively as a plant for the design of the H-infinity controllers and as a model for the simulations of the closed loop suspension systems. In the sequel, the controllers are developed, based on properly defined specifications, for further evaluation and comparison among the systems designed. Robustness verications of the active suspension systems, using the µ-Analysis as assessment tool, are performed together with the performance analysis of each system. The performance evaluation of the systems is performed both in the time domain (assessing angles, speeds, accelerations, dections and the energy of the system) and in the frequency domain (through the analysis of Power Spectral Density (PSD) of vertical accelerations of the vehicle and the control efort of the actuator). The excitation of the system is carried out by means of disturbances imposed to the vertical wheel\'s positions. Those disturbances are of deterministic and stochastic types, which are representatives of real working conditions of the vehicle. The set of controllers developed in this work presents satisfactory results for both deterministic and stochastic input disturbances, with performance gains of the active suspension systems in relation to the passive system of reference up to 34; 92%, 17; 23%, 43; 48% and 30; 10% respectively to the assessment metrics of user comfort, handling maintenance and acceleration of the pitch and roll angles of the chassis.

The forwarder acts as an important role in mechanized Cut-to-Length timber harvesting system. But the majority of forwarder products on the market are not suspended or simply suspended by bogies which limit the riding quality of forwarder and result in soil damage due to large tireground interaction force. The Forestry Research Institute of Sweden is developing an active controlled pendulum arm suspension system actuated by hydraulic cylinders on the forwarder prototype named XT28. The aim of this active suspension system is to compensate the inherent shortcomings of the current suspension solutions. The thesis project focuses on implementing a heterogeneous simulation methodology which integrates the Multi-Body System model of XT28 built in MSC ADAMS/View with active suspension control model developed in MATLAB/Simulink. Thus, the co-simulation process is visualized in ADAMS/View. The results show that the active controlled pendulum arm suspension could improve the riding quality in a large extend and reduce the force between tire and ground at the same time. The cosimulation between ADAMS and Simulink is proved as a feasible and efficient approach to study the active control system for pendulum arm suspension on XT28 forwarder. / Skotaren har tillsammans med skördaren en central roll i den fullt mekaniserade kortvirkesmetoden för skogsavverkning. Majoriteten av dagens skotare på marknaden har sex eller åtta hjul, som är monterade parvis på boggilådor. Det innebär att de saknar chassidämpning, vilket begränsar operatörens komfort och orsakar även stora markskador på mjuk mark. Skogforsk koordinerar realiseringen av en fullskaleprototyp, som går under arbetsnamnet XT28, med sex hjul monterade på varsin pendelarm. Pendelarmarna har varsin hydraulcylinder som möjliggör aktiv helmaskinsdämpning. Detta examensarbete är inriktat på att skapa, demonstrera och verifiera en heterogen simuleringsmetodik, som integrerar och möjliggör samsimulering av en dynamisk mekanikmodell utvecklad i MSC Adams/View med en reglermodell för aktiv styrning av pendelarmarna. Reglermodellen har utvecklats i MATLAB / Simulink. Simuleringsresultaten, som visualiseras i Adams-miljön, visar att den aktiva pendelarmregleringen skulle kunna förbättra åkkomforten signifikant, och också kraftigt markkontaktkrafterna. Det visas att samsimulering mellan ADAMS och Simulink är en effektiv metod för att verifiera prestandan hos aktiva reglersystem för pendelarmsfjädring på prototypskotaren XT28.

Today, Sport Utility Vehicles are marketed as both on-road and off-road vehicles. This results in a compromise when designing the suspension of the vehicle. If the suspension characteristics are fixed, the vehicle cannot have good handling capabilities on highways and good ride comfort over rough terrain. The rollover propensity of this type of vehicle compared to normal cars is high because it has a combination of a high centre of gravity and a softer suspension. The 4 State Semi-active Suspension System (4S4) that can switch between two discrete spring characteristics as well as two discrete damper characteristics, has been proven to overcome this compromise. The soft suspension setting (soft spring and low damping) is used for ride comfort, while the hard suspension setting (stiff spring and high damping) is used for handling. The following question arises: when is which setting most appropriate? The two main contributing factors are the terrain profile and the driver’s actions. Ride comfort is primarily dependant on the terrain that the vehicle is travelling over. If the terrain can be identified, certain driving styles can be expected for that specific environment. The terrains range from rough and uncomfortable to smooth with high speed manoeuvring. Terrain classification methods are proposed and tested with measured data from the test vehicle on known terrain types. Good results were obtained from the terrain classification methods. Five terrain types were accurately identified from over an hour’s worth of vehicle testing. Handling manoeuvres happen unexpectedly, often to avoid an accident. To improve the handling and therefore safety of the vehicle, the 4S4 can be switched to the hard suspension setting, which results in a reduced body roll angle. This decision should be made quickly with the occupants’ safety as the priority. Methods were investigated that will determine when to switch the suspension to the handling mode based on the kinematics of the vehicle. The switching strategies proposed in this study have the potential, with a little refinement, to make the ride versus handling decision correctly. Copyright 2007, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Bester, R 2007, The ride comfort versus handling decision for off-road vehicles, MEng dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-10252007-111611 / > / Dissertation (MEng (Mechanical Engineering))--University of Pretoria, 2007. / Mechanical and Aeronautical Engineering / unrestricted

This report is the result of Master of Science thesis project developed for KTH Royal Institute of Technology in collaboration with the Forestry Research Institute of Sweden (Skogforsk) for the Forestry Master Thesis School 2016. In the past few years, Adams MBD models have been created to verify the better comfortability of six-wheeled pendulum-arm-suspension compared to bogie-suspended forwarder. Based on the current achievements, this thesis would focus on discovering the energy consumption states of both types of forwarder. A study on the energy usage of a pendulum arm suspension forwarder was preformed based on existing design parameters and test data gathered by Skogforsk, providing insight about the performance of XT28 when operating on a test track. Hydraulic and mechanical models of the forwarder were built using Adams and Simulink/Matlab. These models were used for the simulation of the working process and calculation of the energy consumption. The result of this research project shows that active pendulum arm suspension forwarder saves approximately 28% of energy consumption compared to passive suspension. It is also shown that a speed increase from 0.84m/s to 1m/s increases the energy consumptio with approximately 10%. / Rapporten är resultatet av ett masterprojekt som utförts vid KTH Kungliga Tekniska Högskolan i samarbete med Skogforsk för Skogsforskningskolan 2017. Under de senaste åren har ett antal Adams-baserade MBD-modeller skapats, med syftet att undersöka och verifiera hur mycket vibrationsmiljön kan förbättras med en sexhjulig pendelarmsdämpad skotare jämfört med en traditionell bogie-maskin. Denna avhandling fokuserade på att jämföra energiförbrukningen hos båda typer av maskiner. En studie om energiförbrukningen hos en pendularmsskotare har utförts, baserat på befintliga designparametrar och provningsdata insamlade av Skogforsk, vilket gav insikt om energiprestandan hos den aktivt dämpade pendelarmsskotaren XT28 vid drift på provbana. Hydrauliska och mekaniska modeller av maskinen skapades med Adams och Matlab/Simulink. Dessa modeller användes för simulering av en idealiserad arbetsprocess och beräkning av energiförbrukningen. Resultatet av detta projekt visar att aktivt dämpad pendularmsskotare har cirka 28% lägre energiförbrukning jämfört en passivt dämpad skotare. En analys visar också att en ökad hastighet från 0,84 m/s till 1 m/s ökar energiförbrukningen med cirka 10% .

Tyre wear is a vital problem in vehicles, especially in articulated vehicles because of their heavier axle loads. Tyre wear can not only do harm to vehicle dynamics but also cause tyre particle emissions. Therefore, solutions that can minimise tyre wear are where this thesis work focuses. The suspension design is one of the main factors affecting tyre wear. This thesis considers different kinds of semi-active (such as ADD, SH-2 and GH-2) and active suspensions (\(H_\infty\) control) and compares them with a passive suspension with regards to tyre wear. Driving comfort and road holding are considered as well. The simulation starts by running a IPG/TruckMaker model on a route introducing a certain road roughness profile, and outputs lateral slip angles, which together with vehicle parameters and route data are input into a Simulink model. Then, based on the static vertical load on each axles of the articulated vehicle, three different quarter car models corresponding to the axles with various suspension systems are built in Simulink. Simulation results show that the active suspension (\(H_\infty\) control approach) works best in minimising tyre wear, reducing tyre wear by 1-10\% compared to the passive suspension when the vehicle is driving on road profile Class C (country road). Meanwhile, several control strategies of \(H_\infty\) control are applied in order to result in overall good vehicle performance considering comfort and road holding. Semi-active suspensions also work well in reducing tyre wear, but the amount of tyre wear reduction is lower than that of the \(H_\infty\) controllers. / Däckslitage är ett viktigt problem för fordon, särskilt för tunga ledade fordon på grund av deras högre axellaster. Däckets slitage påverkar inte bara fordonets dynamik utan orsakar också utsläpp av däckpartiklar. Olika lösningar behöver utvecklas som kan minimera däckslitage och det är fokus för detta examensarbete. Hjulupphängningens konstruktion är en viktig faktor som påverkar däckslitaget. Detta arbete studerar olika typer av semiaktiva (såsom ADD, SH-2 och GH-2) och aktiva fjädringssystem (\(H_\infty\) reglering) och jämför dem med ett passivt fjädringssystem när det gäller däckslitage, samtidigt som även körkomfort och väghållning beaktas. Simuleringarna inleds med att en IPG/TruckMaker fordonsmodell kör längs en sträcka med en viss typ av vägojämnhet. Simuleringarna resulterar i avdriftsvinklar för fordonet som tillsammans med fordonsparametrar och ruttinformation skapar indata till en Simulink-modell. Därefter, baserat på den statiska vertikala belastningen på varje axel i det ledade fordonet, skapas tre olika kvartsbilsmodeller i Simulink som motsvarar axlarna med deras olika hjulupphängningssystem.Simuleringsresultaten visar att den aktiva fjädringen (\(H_\infty\)) fungerar bäst när det gäller att minimera däckslitage, där slitaget minskar med 1-10\% jämfört med den passiva fjädringen när fordonet kör på vägprofil klass C (landsväg). Samtidigt tillämpas flera olika \(H_\infty\) reglerstrategier för att åstadkomma överlag goda fordonsprestanda även med avseende på komfort och väghållning. Semiaktiva fjädringssystem fungerar också bra för att minska däckslitaget, men minskningen av slitaget är lägre än den för den aktiva \(H_\infty\) fjädringen.