The paper presents construction and control system of the climbing robot Safari designed at the Poznan University of Technology for inspection of high building walls, executed in order to evaluate their technical condition. Because such tasks are uncomfortable and very dangerous for humans, this mobile machine gives a possibility to observe and examine the state of the surface on which it is moving. The robot is a construction developed for walking on flat but uneven vertical and horizontal surfaces. Its on-board equipment provides ability to remotely examine and record images reflecting the robot’s surroundings. At the beginning of the paper, several concepts of existing climbing robots (four-legged, six-legged, sliding platform) are outlined. Next, the mechanical system of the Safari robot is presented with special emphasis on its kinematic equations and description of movement stages. Then, the on-board manipulator as well as the sensor and control systems are described.
In literature, it is known that a Light Emitting Diode (LED) could be used as a light sensor. It is also known that its emitted light spectrum and sensitivity spectrum can be partially overlapped. This work presents how commercial LEDs can be used as light emitters and simultaneously as sensors of the reflected portion of the light emitted by themselves. The realized devices present a unique characteristic: the transmitter and the receiver coincide spatially as they are the same device. This ensures the perfect overlapping between transmission and reception radiation lobes that could provide many benefits in several applications like as distance measurements or image sensors. Some simple electronic configurations that use LEDs as detectors of their own emitted light are presented. It has been also demonstrated how these LEDsTx-Rx can work as image sensors by acquiring an image of a simple test object, and how they can realize distance sensors with respect to other known techniques. Further advantages can be obtained by realizing LEDTx-Rx array in single integrated devices. With the realization of such devices, it will be also possible to experiment new constructive solutions for commonly used applications, without the need of using separate emitter and receiver.
A metamaterial absorber (MA) based sensor is designed and analysed for various important applications including pressure, temperature, density, and humidity sensing. Material parameters, as well as equivalent circuit model have been extracted and explained. After obtaining a perfect absorption (PA) at around 6.46 GHz and 7.68 GHz, surface current distributions at resonance points have been explained. Since bandwidth and applicability to different sensor applications are important for metamaterial sensor applications, we have realized distinctive sensor demonstrations for pressure, temperature, moisture content and density and the obtained results have been compared with the current literature. The proposed structure uses the changes on the overall system resonance frequency which is caused by the sensor layer’s dielectric constant that varies depending on the electromagnetic behaviour of the sample placed in. This model can be adapted to be used in sensor applications including industrial, medical and agricultural products.
Optoelectronic technology plays an important role in medical diagnosis. In the paper a review of some optoelectronic sensors for invasive and non-invasive human health test is presented. The main attention is paid on their basic operation principle and medical usefulness. The paper presents also own research related to developing of tools for human breath analysis. Breath sample unit and three gaseous biomarkers analyzer employing laser absorption spectroscopy designed for clinical diagnostics were described. The analyzer is equipped with sensors for CO, CH4 and NO detection. The sensors operate using multi-pass spectroscopy with wavelength modulation method (MUPASS-WMS) and cavity enhanced spectroscopy (CEAS).
A modified optical fibre based Mach-Zehnder interferometer was applied as a sensor to detect wiretapping in long transmission optical fibre lines. The signal consisting of short pulses (around 1 ns) was launched to the input of the interferometer based on the polarization maintaining fibres and polarization elements. When the sensing line was undisturbed, detectors registered only a single pulse. The additional two side pulses appear, if the wiretapping attempt took place. For robust detection of any alarm situation we proposed two-criteria algorithm to minimize false alarm rate. Moreover, slow environmental fluctuations were continuously monitored and compensated by polarization controllers. We measured frequency characteristics of the sensor and performed a hundred wiretapping attempts, which proved high performance of the sensor.
HPM meters are required for the assessment of fields generated by sources of high-power microwaves. Finding the inverse calibration curves for such instruments is important for ensuring accuracy. The procedure is relatively simple for meters consisting of linear devices but there can also be hardware solutions implementing nonlinear ones. The objective of the present work was to develop a convenient procedure to allow finding such a curve when the meter uses a D-dot probe and a power detector. For that purpose, the results of low voltage measurements describing the properties of the detector were first analysed. Then a software code was developed to estimate the RMS value of an incident field based on measured output and frequency response. The response was estimated with very low electric field. And finally, the performance of the proposed procedure was verified by tests conducted with high electric field in a TEM cell. High conformity of the output of the meter with fields of known values was demonstrated. The maximum error related to the meter range did not exceed 4%.
Water is a sensitive and limited resource, mainly in intensively used agricultural areas in Austria, where groundwater is used as drinking water as well as for irrigation purposes. In order to guarantee a sustainable use of irrigation water, soil water measurement devices can be used to opti-mise irrigation, which means that controlling the soil water content in the entire root system may prevent water stress due to water deficiency on the one hand, and over wetting on the other hand. Furthermore, losses of nutrients due to leaching can be avoided. Several research studies on that topic were initiated during the last few years. The soil water status on selected fields planted with different crops (onions, carrots, sugar beets, sweet maize, zucchini) was monitored continuously by FDR (Fre-quency Domain Reflectometry) soil water measurement devices. Sensors in different depths measure the plant water uptake in the root zone under standard irrigation practices on different sites and dif-ferent soils, respectively. The deepest sensor is installed to avoid deep percolation caused by over irrigation. By means of these data, irrigation could be regulated based on the actual plant water re-quirements to keep the soil water content within an ideal range for crop development.
We experimentally studied three different D-shape polymer optical fibres with an exposed core for their applications as surface plasmon resonance sensors. The first one was a conventional D-shape fibre with no microstructure while in two others the fibre core was surrounded by two rings of air holes. In one of the microstructured fibres we introduced special absorbing inclusions placed outside the microstructure to attenuate leaky modes. We compared the performance of the surface plasmon resonance sensors based on the three fibres. We showed that the fibre bending enhances the resonance in all investigated fibres. The measured sensitivity of about 610 nm/RIUfor the refractive index of glycerol solution around 1.350 is similar in all fabricated sensors. However, the spectral width of the resonance curve is significantly lower for the fibre with inclusions suppressing the leaky modes.
Infrared (IR) science and technology has been mainly dedicated to surveillance and security: since the 70’s specialized techniques have been emerging in thermal imaging for medical and cultural heritage diagnostics, building and aeronautics structures control, energy savings and remote sensing. Most of these applications were developed thanks to IR FPAs sensors with high numbers of pixels and, actually, working at room temperatures. Besides these technological achievements in sensors/ receivers, advanced developments of IR laser sources up to far IR bands have been achieved in the form QCL (quantum cascade laser), allowing wide band TLC and high sensitivity systems for security. recently new sensors and sources with improved performances are emerging in the very far IR region up to submillimeter wavelengths, the so called terahertz (THz) region.
A survey of the historical growth and a forecast of the future developments in Devices and Systems for the new frontier of IR will be discussed, in particular for the key questions: “From where and when is IR coming?”, “Where is it now?” and “Where will it go and when?”. These questions will be treated for key systems (Military/Civil), key devices (Sensors/ Sources), and new strategic technologies (Nanotech/TeraHertz).
We experimentally studied three different D-shape polymer optical fibres with an exposed core for their applications as surface plasmon resonance sensors. The first one was a conventional D-shape fibre with no microstructure while in two others the fibre core was surrounded by two rings of air holes. In one of the microstructured fibres we introduced special absorbing inclusions placed outside the microstructure to attenuate leaky modes. We compared the performance of the surface plasmon resonance sensors based on the three fibres. We showed that the fibre bending enhances the resonance in all investigated fibres. The measured sensitivity of about 610 nm/RIU for the refractive index of glycerol solution around 1.350 is similar in all fabricated sensors. However, the spectral width of the resonance curve is significantly lower for the fibre with inclusions suppressing the leaky modes.
In this paper, we present a fibre-optic sensor for simultaneous measurement of refractive index and thickness of liquid layers.We designed an experimental low-coherence setup with two broadband light sources and an extrinsic fibre-optic Fabry–Pérot interferometer acting as the sensing head.We examined how the refractive index of a liquid film and its thickness affect spectrum at the output of a fibre-optic interferometer. We performed a series of experiments using two light sources and only one sensing head. The spectra were collected in ranges of 1220÷1340 nm and 1500÷1640 nm. The obtained results show that using two spectra recorded simultaneously for two wavelength ranges enables to determine thickness in a range of 50÷500 μm, and refractive index of a liquid film in a range of 1:00÷1:41 RIU using only one sensing head.
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