Search the digital library catalog

Abstract: This study proposed an approach for robot localization using data from multiple low-cost sensors with two goals in mind, to produce accurate localization data and to keep the computation as simple as possible. The approach used data from wheel odometry, inertial-motion data from the Inertial Motion Unit (IMU), and a location fix from a Real-Time Kinematics Global Positioning System (RTK GPS). Each of the sensors is prone to errors in some situations, resulting in inaccurate localization. The odometry is affected by errors caused by slipping when turning the robot or putting it on slippery ground. The IMU produces drifts due to vibrations, and RTK GPS does not return to an accurate fix in (semi-) occluded areas. None of these sensors is accurate enough to produce a precise reading for a sound localization of the robot in an outdoor environment. To solve this challenge, sensor fusion was implemented on the robot to prevent possible localization errors. It worked by selecting the most accurate readings in a given moment to produce a precise pose estimation. To evaluate the approach, two different tests were performed, one with robot localization from the robot operating system (ROS) repository and the other with the presented Field Robot Localization. The first did not perform well, while the second did and was evaluated by comparing the location and orientation estimate with ground truth, captured by a hovering drone above the testing ground, which revealed an average error of 0.005 m±0.220 m in estimating the position, and 0.6°±3.5° when estimating orientation. The tests proved that the developed field robot localization is accurate and robust enough to be used on a ROVITIS 4.0 vineyard robot.
Keywords: localization, odometry, IMU, RTK GPS, vineyard, robot, sensors fusion, ROS, precision farming
Published in DKUM: 02.07.2024; Views: 123; Downloads: 13
Full text (690,56 KB)
This document has many files! More...

Abstract: An electrochemical sensor for the detection of insulin in a single drop (50 μL) was developed based on the concept of molecularly imprinted polymers (MIP). The synthetic MIP receptors were assembled on a screen-printed carbon electrode (SPCE) by the electropolymerization of pyrrole (Py) in the presence of insulin (the protein template) using cyclic voltammetry. After electropolymerization, insulin was removed from the formed polypyrrole (Ppy) matrix to create imprinting cavities for the subsequent analysis of the insulin analyte in test samples. The surface characterization, before and after each electrosynthesis step of the MIP sensors, was performed using atomic force microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The performance of the developed MIP–SPCE sensor was evaluated using a single drop of solution containing K3Fe(CN)6 and the square-wave voltammetry technique. The MIP–SPCE showed a linear concentration range of 20.0–70.0 pM (R2 = 0.9991), a limit of detection of 1.9 pM, and a limit of quantification of 6.2 pM. The rapid response time to the protein target and the portability of the developed sensor, which is considered a disposable MIP-based system, make this MIP–SPCE sensor a promising candidate for point-of-care applications. In addition, the MIP–SPCE sensor was successfully used to detect insulin in a pharmaceutical sample. The sensor was deemed to be accurate (the average recovery was 108.46%) and precise (the relative standard deviation was 7.23%).
Keywords: electrochemical sensors, electropolymerisation, electron microscopy
Published in DKUM: 14.03.2024; Views: 335; Downloads: 36
Full text (2,91 MB)
This document has many files! More...

Abstract: This paper describes a Fabry-Perot sensor-based measuring system for measuring fluid composition in demanding industrial applications. The design of the sensor is based on a two-parametric sensor, which enables the simultaneous measurement of temperature and refractive index (RI). The system was tested under real industrial conditions, and enables temperature-compensated online measurement of emulsion concentration with a high resolution of 0.03 Brix. The measuring system was equipped with filtering of the emulsion and automatic cleaning of the sensor, which proved to be essential for successful implementation of a fiber optic RI sensor in machining emulsion monitoring applications.
Keywords: optical fiber sensors, Fabry–Pérot interferometer, refractive index, temperature, emulsion concentration
Published in DKUM: 06.02.2024; Views: 336; Downloads: 26
Full text (4,44 MB)
This document has many files! More...

Abstract: This work presents a novel smartphone testing platform for the validation of colorimetric sensor receptors (CSRs) in the form of layers that enables reliable and straightforward determination of their color change in a closed system using a commercially available color sensor. The food-compatible model CSR used for the method development was made of black carrot extract and ethyl cellulose. The colorimetric responses were studied in detail for NH3, dimethylamine (DMA), and trimethylamine (TMA) by analyzing changes in the value of the total color difference (ΔE) with the increasing logarithm of the mass concentration (log γ) of the analytes. The method was partially validated for the detection limit (LOD), the limit of quantification, sensitivity, and linear γ range. The fastest reaction times were obtained for the NH3 analyte, while the calculated LOD values were quite similar (1.48 mg L−1 for NH3, 1.55 mg L−1 for DMA, and 1.58 mg L−1 for TMA). The applicability of CSRs was shown for different types of muscle food. Frozen (boneless and skinless) hake fillets were used for additional experimental work in which the color changes of the CSRs were correlated with the values of the total volatile basic nitrogen (TVB-N) and the total counts of aerobic and anaerobic microorganisms. The developed testing platform shows great promise for the development of CSRs that define the quality of a broad variety of muscle food.
Keywords: sensors receptors, CSRs, colorimetric
Published in DKUM: 01.08.2023; Views: 781; Downloads: 45
Full text (1,64 MB)
This document has many files! More...

Abstract: In the master thesis, we have created an interrogation system for measuring the change of the optical path in the Fabry-Perot interferometer caused by the strain of the surface at which it was attached to. The change of strain can be calculated via a change in optical path length which is visible as a shift in phase angle. The system will be used as a system for measuring strain, although it can be used for measuring various physical parameters that can cause a change in optical path length, such as pressure, force, temperature, etc. Initially, the theoretical background of the system and project components are represented and explained, following the building process of the electronic and optical part of the project. Lastly, the working principle and programming algorithms of a system are presented and explained. Measurement results are shown at the end, as well as the conclusion that is drawn from the thesis.
Keywords: optical fibers, sensors, interferometer, signal processing
Published in DKUM: 04.11.2020; Views: 1244; Downloads: 116
Full text (5,11 MB)