Texas Instruments | EPFL Graph Search

Texas Instruments Incorporated (TI) is an American technology company headquartered in Dallas, Texas, that designs and manufactures semiconductors and various integrated circuits, which it sells to electronics designers and manufacturers globally. It is one of the top 10 semiconductor companies worldwide based on sales volume. The company's focus is on developing analog chips and embedded processors, which account for more than 80% of its revenue. TI also produces TI digital light processing technology and education technology products including calculators, microcontrollers, and multi-core processors. The company holds 45,000 patents worldwide as of 2016. Texas Instruments emerged in 1951 after a reorganization of Geophysical Service Incorporated, a company founded in 1930 that manufactured equipment for use in the seismic industry, as well as defense electronics. TI produced the world's first commercial silicon transistor in 1954, and the same year designed

Mechatronic elements and haptic rendering for computer-assisted minimally invasive surgery training

Thomas Moix

Technological advances of the last decades enabled the development of a set of new medical techniques that differ from traditional open surgery. These techniques, referred to as minimally invasive surgery (MIS), involve complex instruments and imaging devices to reach and treat anatomical regions through small incisions or natural entry points resulting in reduced trauma and shorter recovery time. For the surgeons, MIS introduces unnatural hand-eye coordination and anatomical representation that require specific training. One alternative is the use of virtual reality (VR) simulations of MIS procedures coupled to input devices mimicking instruments used by surgeons. To achieve high-fidelity with such a computer-assisted training system, the input device also provides the sensations experienced during a procedure with force reflective technology, often referred to as haptics. This work explores the mechatronic aspects implied in the realization of such a haptic device for MIS training applications. An analysis of different MIS procedures enables to draw two categories: lumen-guided and cavity procedures. A simple classification of the required mechanism can be extracted from these observations. To fulfil the requirements, an implementation should follow a series of guidelines in terms of actuation and power transmission that are presented. The interactions between a human operator and a haptic interface involve both force and motion. Impedance control generates a force command based on the position of the haptic interface. This process, called haptic rendering, is an integrate part of the VR environment. This work proposes to extend impedance control with model-based compensation of the dynamics and non-linearities (such as friction) of the haptic device. Due to sensitivity to model uncertainties, the proposed control architecture is completed by a parallel implicit force controller. Since the computational load of VR simulation for complex anatomies is high, update rates reach 20 to 30 Hz. These frequencies are not sufficient to control a haptic device and meet the sensitivity requirements of the human sensory system. Therefore, in such system a multirate approach is introduced. A model is proposed for the dynamics of a haptic interface and its user. Based on this model, the effect of the introduced implicit force controller is studied and different interfacing techniques between the VR simulation and the haptic controller are evaluated. Since force sensing is a requirement for the implementation of the proposed implicit forcecontroller, a technique using infrared reflective sensors is proposed. A modelling method for such sensors is introduced and implementation issues for force sensing are discussed. Finally, the topics discussed in this work are applied to the development of a computer-assisted training system for Interventional Radiology.

EPFL2005

Investigation of femtosecond laser-tuned thermomechanical properties of fused silica

Pieter Vlugter

The thermomechanical properties of materials are among the most important properties for designing precision instruments, in particular for devices seeking high-dimensional stability, invariant temperature-elastic properties or low thermoelastic losses. Dedicated materials have been created for these purposes, such as ZerodurÂ® and SilinvarÂ®. In this thesis work, we propose a method for selectively tuning the thermomechanical behavior of transparent materials using ultrafast lasers. Specifically, we investigate laser-exposed fused silicaâs thermal expansion coefficient and thermoelastic properties. Fused silicaâs already outstanding physical properties, low-thermal expansion coefficient and such as low thermoelastic losses, offers a promising starting point for exploring its limits as a high performance thermomechanical materials. This study unraveled the preponderance of certain laser induced modifications in this pro-cess. The results are obtained using designed micro-mechanical devices. A bimorph structure is used to characterize the thermal expansion, while a resonant cantilever is implemented for investigating thermoelastic properties. Using these micro-instruments, we show that: 1) These laser-induced modifications can be used to tune silica thermal expansion coefficient perma-nently. In particular, we demonstrate that a given exposure regime leads to a lower thermal expansion than the pristine material, while other exposure conditions yield the opposite result. 2) The positive temperature-elastic coefficient of silica is reduced by nearly 50% after laser exposure. Such performance turns fused silica into a good candidate for temperature-stable resonators. 3) The Youngâs modulus at room temperature can display laser-induced elastic anisotropy controlled by the laser polarization. 4) The thermomechanical properties can be fine-tuned with an extra thermal annealing step. This thesis is a first step towards designing materials with arbitrary thermomechanical behavior, starting from a given transparent material. This approach stands out from other methods as the material properties can selectively be transformed at the microscale level with unique and tailored thermomechanical properties, and this, in arbitrary substrate shapes. It enables the fabrication of metamaterials with designed thermomechanical response. From a device point-of-view, this research further expands the capability of femtosecond laser to tune refractive index and etching selectivity towards thermomechanical properties, forming a larger palette of possible ultrafast laser-induced functionalities. This addition further enlarges the potential of femtosecond laser for making highly integrated multifunctional devices. This is in particular interesting for precision instruments, temperature-responsive sensors and actuators, as well as temperature-stable optomechanical devices.

EPFL2020

A digitally controlled 125 kVdc, 30kW power supply with an LCC resonant converter working at variable DC-link voltage: Full scale prototype test results

Mauro Carpita, Mario Paolone

In this paper, a high output voltage power converter working at variable input DC-link voltage is presented. The variable DC link voltage opens to very interesting solution at system level. However, those solutions will be the subject of futures papers. Only the main power converter structure is presented here. After an evaluation of the most promising converter topologies for the required high voltage and power, eventually an LCC resonant converter with phase shift control has been chosen. The resonant converter is followed by a double secondary high frequency transformer with a two diode voltage doublers. The system has been fully analysed from the theoretical point of view, designed, built and tested. The control system has been fully digital implemented making use of a TI DSP microcontroller, TMS320X28335.