Réponse indicielle

Résumé

En automatique la réponse indicielle est la réponse d'un système dynamique à une fonction marche de Heaviside \sigma (t)\ communément appelée échelon. Si le système est un système linéaire invariant (SLI) à temps continu ou discret, alors la réponse indicielle est définie par les relations respectives suivantes : :a(t) = (h * \sigma)(t) = \int\limits_{-\infty }^\infty h(\tau)\sigma (t - \tau) d\tau = \int\limits_{-\infty }^t h(\tau) d\tau :a(n) = (h * \sigma)(n) = \sum_k h(k) \sigma(n-k) = \sum_{k=-\infty}^n h(k) Lorsque le système est asymptotiquement stable, la réponse indicielle converge vers une valeur limite (asymptote horizontale) appelée valeur stationnaire ou finale. Dans ce cas, la réponse indicielle possède les caractéristiques suivantes : *Dépassement : la différence entre sa valeur maximale et la valeur finale (parfois exprimée en valeur relative). *Temps de montée : le temps nécessaire pour qu’elle passe de 10 % à 90 % de la val

Source officielle

https://fr.wikipedia.org/wiki/R%C3%A9ponse_indicielle

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Apporter aux étudiants les connaissances de base nécessaires à la modélisation et à l'analyse des systèmes dynamiques. Leur apprendre à concevoir des régulateurs et à analyser la performance des systèmes commandés.

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This course introduces the analysis and design of linear analog circuits based on operational amplifiers. A Laplace early approach is chosen to treat important concepts such as time and frequency responses, convolution, and filter design. The course is complemented with exercises and simulations.

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Jamie Paik, Yun Seong Song, Yi Sun

Conventional pneumatic actuators have been a popular choice due to their decent force/torque output. Nowadays, new generation of pneumatic actuator made out of highly compliant elastomers, which we call soft pneumatic actuators (SPA), are drawing increasing attention due to their ease of fabrication, high customizability and innately softness. However, there is no effective method presented to characterize and understand these actuators, such as to measure the force and torque output, range of motion and the speed of actuation. In this work, we present two types of SPAs: bending and rotary actuators. In addition, we have developed two measurement setups to characterize actuators of different geometries. The measured force/torque outputs of different actuators are presented and analyzed. Step responses to certain pressure input are presented and discussed. A simple model is presented to provide physical insight to the observed behavior of the soft actuators. This work provides the basis for designing customized SPAs with application-specific requirements.

Ieee2013

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Nowadays, hearing impaired people can be treated with a multitude of different devices and surgical interventions that are selected in function of the type and degree of hearing loss of the patient. These known therapies cover the major part of possible hearing losses except severe to profound mixed hearing loss. The present thesis results from an industrial project that aims to develop a dedicated hearing therapy that treats this kind of hearing loss based on direct acoustic cochlear stimulation (DACS). A semi-implantable investigational hearing device is used in a clinical trial with four patients to validate this novel therapy approach. The development of this investigational hearing implant presents a considerable challenge due to the numerous medical and engineering aspects that have to be considered. The conceptual design process is therefore of central importance because it incorporates all the relevant aspects and defines the future device characteristics and performances. Fundamental design aspects that are not considered at this early design stage can only be implemented with difficulties and increased efforts later on. This is the motivation to develop within the scope of this thesis a conceptual design methodology that supports and facilitates this essential design phase. A conceptual design methodology for acoustic hearing implants is therefore presented at the example of the DACS investigational device. The methodology consists of a four-step-procedure and a system diagram tool. The four steps of the procedure are: Step 1: determination and analysis of the human body functions that shall be emulated by the system Step 2: determination of the preliminary system architecture Step 3: determination of the user and system requirements Step 4: conceptual design The system diagram tool guides the engineer through all four steps and helps visualizing and structuring the system environments, functions, interfaces and, most important, all interactions between the system elements and environments. The diagram drawing rules ensure that all requirements coming from the environments are correctly linked with the concerned system functions and therefore ensure that the system meets all these requirements. Finally, the system diagram is a valuable tool for the conceptual design step. Because of the clearly represented system elements and interactions, it supports the development of integrated solutions. The output of the presented methodology is a design concept that cannot be directly quantified to assess the benefit of the methodology. Only once the resulting device is successfully verified against the system requirements and validated against the user requirements, it can be concluded that the underlying concept is adequate. The outcome of the clinical study shows that the four implanted patients benefit all from the DACS device, which is therefore well suited to treat severe to profound mixed hearing loss. This confirms that device meets the user requirements and implies that conceptual design methodology is adequate. The realized investigational device consists of an externally worn audio processor, a percutaneous connector, and an implantable actuator. The hermetically sealed balanced armature actuator provides a maximal equivalent sound pressure level of 125 dB over the frequency range between 100 Hz and 10'000 Hz with a limited 1-mW power supply. A lumped parameter model of the actuator dynamics and a finite element model of the electro-mechanic actuator are used for the detailed actuator design.

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Advanced Materials Enabling High-Volume Road Transport Applications of Lightweight Structural Composite Parts

Jan-Anders Månson, Véronique Michaud, Ignaas Herman Johannes Verpoest

Current applications of carbon fibre reinforced plastics (CFRP) can be found mostly in sectors where their use is not principally cost-driven and which have limited production volumes, such as aerospace and sports cars. In order to achieve a step-change in the application of high-performance composites in larger-volume applications, new materials systems are needed that combine very short production cycle times with performance that meets automotive requirements. The EU-FP 7-project HIVOCOMP is developing two material systems that show unique promise for cost effective, higher-volume production of high performance carbon fibre reinforced parts. These materials systems are: Advanced polyurethane (PU) thermoset matrix materials offering a combination of improved mechanical performance and reduced cycle times in comparison with conventional matrix systems, Thermoplastic PP- and PA6-based self-reinforced polymer composites incorporating continuous carbon fibre reinforcements offering increased toughness and reduced cycle times in comparison to current thermoplastic and thermoset solutions. In this introduction, the global concept of the HIVOCOMP-project is presented, and an overview is given of the achievements during the first three project years. Emphasis is then put on the demonstrators (see figures) and how they show the advantages of both innovative material concepts, both in processing (reduced cycle times) and in properties (increased toughness). Finally, the environmental impact of these new material concepts is evaluated by reporting on the results of the LCA (life cycle assessment) and LCC (life cycle costing) studies.

Sampe Publishers2014

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EPFL2011