Mario Pauli

High-Accuracy Range Detection Radar Sensor for Hydraulic Cylinders

Industrial automation requires highly precise distance measurement sensors. Accurate detection of the piston position is indispensable for the control and monitoring of hydraulic cylinder applications. Known external and integrated solutions are subject to many limitations as for example in accuracy, in measurement length, or in price. A promising approach consists in the use of precise and low-cost radar sensors. The developed K-band frequency modulated continuous wave (FMCW) radar system in this paper detects the piston position in a hydraulic cylinder based on the guided propagation of a radar signal. The dielectric characteristics of the hydraulic oil are obtained for this purpose by permittivity measurement methods. Influences of the hydraulic oil on wave propagation in cylindrical waveguides as well as mechanical requirements associated with this new approach are investigated. The design of an adapted oil- and pressure-resistant transition between the radar sensor and the hydraulic cylinder and a novel calibration method will be described and verified under real measurement conditions. At a measurement repetition rate of 2 kHz, an accuracy of well below 200 μm was achieved for a hydraulic cylinder of 1 m in length.

122-GHz chip-to-antenna wire bond interconnect with high repeatability

This paper presents a 122-GHz chip-to-antenna wire bond interconnect for low-cost, fully integrated transceivers. It is based on the standard ball-stitch bond technology and uses planar transmission lines for matching. A study on the effects of process tolerances is given. Finally, an antenna which is integrated into a QFN plastic package is characterized together with the chip-to-antenna interconnect.

An Efficient Frequency and Phase Estimation Algorithm With CRB Performance for FMCW Radar Applications

In this paper, a chirp z-transform (CZT)-based algorithm for frequency-modulated continuous wave (FMCW) radar applications is presented. The proposed algorithm is optimized for real-time implementation in field-programmable gate arrays. To achieve a very high accuracy, the FMCW radar uses an additional phase evaluation. Therefore, a phase calculation based on the CZT algorithm is derived and compared with a correlation based algorithm. For a better classification of the algorithm, the respective Cramér-Rao bounds are calculated. The performance of the algorithm is shown by the evaluation of different radar measurements with a K-band radar. In the measurements, an accuracy of 5 μm with a mean standard deviation of 774 nm is achieved, which nearly matches the theoretically predicted mean standard deviation of 160 nm.

A versatile measurement system for the determination of dielectric parameters of various materials

In this paper, a versatile method for the determination of the complex permittivity of materials from measured scattering parameters is presented. The measurement set-up consists of a waveguide applicator for housing the material sample. The considered frequency range is 2?3 GHz. The complex scattering parameters are measured by a vector network analyser. The algorithm for computing the complex permittivity from the measured scattering parameters is shown in detail and an error estimation is performed. Depending on the waveguide layout liquid, granular and solid materials can be measured. To measure granular and liquid samples two dielectric walls inside the waveguide are used to house the samples. The dielectric parameters of different soils as well as of some liquids are determined with consideration of their moisture content and temperature. In contrast to several other techniques, this measurement set-up is also suited for high loss materials. The set-up has also been successfully used for measurements of anisotropic materials.

Millimeter-wave radar distance measurements in micro machining

In production and automation engineering the need for highest precision distance sensors is ubiquitous especially in the field of micro-machining processes where an extremely accurate positioning is indispensable. Although the work pieces become smaller and smaller many machine tools stay big and heavy. The reason for this is that a high precision is necessary and in this way the machine tools must be robust and stiff in their rails to prevent positioning errors due to tilts or twists. By using accurate sensors integrated in the rails of the machine tool the positioning error increases since the distance between the measurement of the position and the machine tool itself is relatively large. For this reason it might be advantageous to measure as close as possible at the tool center point (TCP) which could also allow for a reduction in machine sizes. A radar system might be a promising approach for this measurement due to the progressive development in radar technology along with new and fast algorithms. In this paper an frequency modulated continuous wave (FMCW) radar system is presented working around a center frequency of 80 GHz with a modulation bandwidth of 10 GHz. In combination with an innovative signal processing concept that uses frequency and phase evaluation a sub-micrometer accuracy can be achieved over distances up to several meters. The high accuracy of ±0.5 μm is demonstrated in a novel measurement setup for a kinematic using compliant mechanisms with flexure hinges.

Radar-Based High-Accuracy Angle Measurement Sensor Operating in the K-Band

The growing need for high-precision measurement instruments in modern industrial facilities leads to new measurement principles to reduce sensor costs while maintaining accuracy. A novel measurement principle suited for these applications is based on radar, which originally is associated with measurements in free space. For high precision, guided waves can be used to prevent disturbing reflections from the environment. Another advantage of a waveguide-based measurement is that the electromagnetic wave can be guided in a circle to measure rotational motions, which are in particular relevant in machine tools. This paper describes an FMCW radar sensor in the K-band for angle measurements. The sensor principle is described in detail, including its high-frequency components and the mechanical constraints to achieve a full angle range of 360°. The propagation characteristics of the radar signal in a curved waveguide with an adapted feeding structure using a Riblet coupler are presented. In addition to simulations, measurements with a prototype setup are presented to verify the radar-based angle measurement principle. The achieved accuracy is ±0.05° which corresponds to an accuracy in distance of ±125 μm.

Range detection with micrometer precision using a high accuracy FMCW radar system

In metal machining processes highly accurate distance sensors are indispensable. Due to the progressive development, radar technology could be used for this sensor application. In contrast to other highly accurate measurement systems, radar technology promises a low-cost solution with comparable performance. In this paper a FMCW radar sensor is used for an accurate position detection with micrometer accuracy. A signal processing concept is introduced that combines frequency and phase evaluation to achieve the desired accuracy over a longer distance of up to 3m. The high accuracy is demonstrated within a guided wave measurement setup.

Impact of Frequency Ramp Nonlinearity, Phase Noise, and SNR on FMCW Radar Accuracy

One of the main disturbances in a frequency-modulated continuous wave radar system for range measurement is nonlinearity in the frequency ramp. The intermediate frequency (IF) signal and consequently the target range accuracy are dependent on the type of the nonlinearity present in the frequency ramp. Moreover, the type of frequency ramp nonlinearity cannot be directly specified, which makes the problem even more challenging. In this paper, the frequency ramp nonlinearity is investigated with the modified short-time Fourier transform method by using the short-time Chirp-Z transform method with high accuracy. The random and periodic nonlinearities are characterized and their sources are identified as phase noise and spurious. These types of frequency deviations are intentionally increased, and their influence on the linearity and the IF-signal is investigated. The dependence of target range estimation accuracy on the frequency ramp nonlinearity, phase noise, spurious, and signal-to-noise ratio in the IF-signal are described analytically and are verified on the basis of measurements.

Modeling of Mutual Coupling Between Electromagnetic and Thermal Fields in Microwave Heating

This paper presents the analysis and modeling of the mutual coupling between thermal and electromagnetic fields. During the microwave heating process the microwaves are dissipated to heat due to the dielectric losses of the medium. The heat propagation inside the medium depends on its thermal parameters as well as on different propagation mechanisms. In most cases the dielectric properties are dependent on the temperature. In this paper a model is described for a microwave assisted soil decontamination system. The dielectric properties of the soil not only depend on temperature but also on the moisture content which reduces during the heating process. With changing dielectric properties of the soil the electromagnetic field distribution changes as well which again has an influence of the heat propagation. The basic principles of microwave heating and heat propagation are explained in this paper, as well as a simulation model based on an FEM code. To prove the correctness of the model a comparison with measurement results is given.

Miniaturized Millimeter-Wave Radar Sensor for High-Accuracy Applications

A highly miniaturized and commercially available millimeter wave (mmw) radar sensor working in the frequency range between 121 and 127 GHz is presented in this paper. It can be used for distance measurements with an accuracy in the single-digit micrometer range. The sensor is based on the frequency modulated continuous wave (CW) radar principle; however, CW measurements are also possible due to its versatile design. An overview of the existing mmw radar sensors is given and the integrated radar sensor is shown in detail. The radio frequency part of the radar, which is implemented in SiGe technology, is described followed by the packaging concept. The radar circuitry on chip as well as the external antennas is completely integrated into an 8 mm