Decision making at unsignalized inner city intersections using discrete events systems

Autonomous driving is a promising technology to, among many aspects, improve road safety. There are however several scenarios that are challenging for autonomous vehicles. One of these are unsignalized junctions. There exist scenarios in which there is no clear regulation as to is allowed to drive first. Instead, communication and cooperation are necessary to solve such scenarios. This is especially challenging when interacting with human drivers. In this work we focus on unsignalized T-intersections. For that scenario we propose a discrete event system (DES) that is able to solve the cooperation with human drivers at a T-intersection with limited visibility and no direct communication. The algorithm is validated in a simulation environment, and the parameters for the algorithm are based on an analysis of typical human behavior at intersections using real-world data.

Online harmonic error compensation of Atan2 function for a low-cost automotive sensor application

A new compensation method of harmonic distortions by using Atan2 function is introduced in this paper. It provides a simple online calibration function to determine the parameters of harmonic distortions. Thus, it can be implemented in a microcontroller with less computational capacity and can increase the accuracy of a low-cost angle position sensor for automotive applications.

Frequency and mode measurement techniques for megawatt-class gyrotrons

State-of-the-art vacuum electron tubes such as gyrotrons, deliver RF output powers up to more than 2 MW at frequencies up to 170 GHz. In terms of the very high power levels, a proper verification of the gyrotron components itself and measurements during gyrotron operation are vital to prevent possible fatal errors. Several basic RF measurement setups, which are used at IHM/KIT, are discussed. Currently, their upper frequency limit is 175 GHz. In terms of future gyrotron operation above 200 GHz, upgrades of the measurement setups for operation up to 260–330 GHz are prepared. The experimental devices discussed herein are a quasi-optical mode generator for the verification of the quasi-optical gyrotron output system, the window measurement test stand to verify the ceramic gyrotron output window and the frequency diagnostic system to measure the operating frequency and thereby the excited mode.

Tunable nanopillar array on a quartz-fiber tip for surface enhanced Raman scattering (SERS) detection

In this work, a simple two-step method to create tunable self-assembled three-dimensional nanostructure array-like nanoantennas directly on the tip of an optical quartz glass fiber is described. The structures are prepared by using dry etching of the fiber tip. For the etching process, gold nanoparticles fabricated by thermal dewetting technique were used as template. The structures are applied as sensors for label-free analysis of organic substances in ppb range, such as drug residues in liquid solutions. The measurements are carried out by a portable Raman device with an exchangeable sensor head utilizing the SERS-effect. This method allows in situ applications. In order to characterize the SERS cells, para-thiocresol and diclofenac sodium are used as model substances. For optimization of the substrate performance, different thicknesses of the dewetting-layer (6, 9, 12 nm), different etching times for formation of the pillars (6, 8, 10 and 12 min), and different thicknesses of SERS-metallization (25, 50, 75 nm) of gold and silver are compared. In order to show the applicability of the structure on the tip of a fiber, measurements from the upper side and from the underside of the substrate on quartz plates are compared. Reproducible SERS enhancement factors up to 10 7 {10^{7}} were achieved.

Two-component gas sensing with MIR dual comb spectroscopy

A dual comb spectrometer is used as gas sensor for the parallel detection of nitrous oxide (N2O) and carbon monoxide (CO). These gases have overlapping absorption features in the mid-infrared (MIR) at a wavelength of 4.6 µm. With a spectra acquisition rate of 10 Hz, concentrations of 50 ppm N2O and 30 ppm CO are monitored with a relative precision of 6 × 10 − 3 6\times {10^{-3}} and 3 × 10 − 3 3\times {10^{-3}} respectively. The limit of detections are 91 ppb for N2O and 50 ppb for CO for an integration time of 25 s. The system exhibits a linear sensitivity from 2 ppm to 100 ppm with coefficients of determination of 0.99998 for N2O and 0.99996 for CO.

Messung der Homogenität der Strahldichte einer Ulbricht-Kugel mit großer Apertur im SWIR mit einer InGaAs-Infrarotkamera

Zusammenfassung Wir stellen die Untersuchung der Homogenität der Strahldichte einer Ulbricht-Kugel mit großer Apertur vor, die mit einer InGaAs-Kamera im Wellenlängenbereich des SWIR gemessen wurde. Ein in der PTB entwickeltes Verfahren wird verwendet, um die Ungleichförmigkeit der relativen spektralen Empfindlichkeit der verwendeten Infrarotkamera zu korrigieren. Es werden verschiedene Konfigurationen untersucht und die Eignung der untersuchten Ulbricht-Kugel zur Charakterisierung von IR-Kameras geprüft. Es wurde festgestellt, dass die Ulbricht-Kugel eine Homogenität ihrer Strahldichte von ±1 % im integralen Wellenlängenbereich von 0,9 µm bis 1,7 µm aufweist.

Implementation of a mobile spectrometer using a near infrared MEMS Fabry–Pérot interferometer sensor

Miniaturised MEMS-based Fabry-Pérot interferometer (FPI) spectral sensors allow the design of compact spectrometers in the near infrared (NIR) range. These small-size instruments can be used for quality control of alimentation products, sorting of plastics and fabrics in respect to the material composition or defining genuineness of goods. This article describes design details and achieved results in development of an inexpensive user friendly hand-held NIR spectrometer incorporating a MEMS-FPI sensor with the spectral range of 1550–1850 nm. Implemented electronic circuitry as well as the optical configuration of the device are discussed, used electronic components and the background for the choice of the light source are presented. Furthermore, the associated software for device operation and data visualisation is described. Achieved technical parameters of the device are discussed and illustrated by examples of acquired spectra. Shared experience in operating a MEMS-FPI sensor could be especially useful for designers targeting low-cost instruments for use by general public.