Low-cost Radar Sensor Research Articles

Autonomous Wireless Sensor System for Emergency Monitoring Roads with Low Communication Coverage

Rural areas often face communication challenges due to limited mobile coverage on remote roads, posing significant difficulties in reporting emergencies and accidents. This study presented an autonomous vehicle tracking system using low-cost radar sensors to detect possible emergencies in the sections of roads with low cell coverage. The radar sensor system could determine the number of vehicles that passed through the nodes and classify them based on the vehicle type. Each node within the system is equipped with ten radars, a processor unit, and a radio transmitter to communicate with the network in real-time, achieving a rapid response time of just 0.2 s. To ensure seamless connectivity, two distinct wireless communication networks are employed, one for the connection between the towers in the same node and the other for the connection between nodes and a center with cellular coverage. The results of this study can be useful in conveying emergency messages, as well as traffic management.

A Noncontact Fall Detection Method for Bedside Application With a MEMS Infrared Sensor and a Radar Sensor

With the rapid development of economy, science and technology, the aging issues become more and more serious. People aged above 65 have a risk of 28%-35% to fall. Among them, bedside falls happen most frequently. Therefore, the capability to detect fall events of the elderly is very important. In this paper, a novel non-contact fall detector based on a MEMS low-resolution infrared sensor and a low-cost radar sensor is developed to detect bedside fall. Besides, IR image processing algorithms based on adaptive filter, successive approximation, double boundary scans and mathematical morphology processing are proposed detailedly. Partition processing algorithm is used to suppress the influence of residual or existed heat sources on the bed or ground. Then, the statistical features of the center, area, temperature and duration, as well as stable flag and fall action flag, are extracted for fall recognition. Finally, a three-layer RBF neural network is applied to distinguish the fall events from the non-fall events. Considering the influence factors of ambient temperature, brightness, gender, dressing, fall posture, fall location and scenario, a total of 640 tests are conducted and 5-fold cross validation is used to evaluate the classification performance. Experimental results indicate that the averages of the recall, precision, F1-Score and detection accuracy are measured to be 91.25%, 94.76%, 92.97% and 93.13%, respectively, which demonstrates that the proposed fall detection method is effective. Besides, the detection accuracy decreases from 96.88% to 85.94% as the ambient temperature rises. Hence, this non-contact fall detector can be widely applied for bedside fall detection at home, which is low-cost, non-wearable, unobtrusive, non-invasive and privacy-preserved.

Using Low-Cost Radar Sensors and Action Cameras to Measure Inter-Vehicle Distances in Real-World Truck Platooning

Many modern vehicles collect inter-vehicle distance data from radar sensors as input to driver assistance systems. However, vehicle manufacturers often use proprietary algorithms to conceal the collected data, making them inaccessible to external individuals, such as researchers. Aftermarket sensors may circumvent this issue. This study investigated the use of low-cost radar sensors to determine inter-vehicle distances during real-world semi-automated truck platooning on two-way, two-lane rural roads. Radar data from the two follower trucks in a three-truck platoon were collected, synchronized and filtered. The sensors measured distance, relative velocity and signal-to-noise ratio. Dashboard camera footage was collected, coded and synchronized to the radar data, providing context about the driving situation, such as oncoming trucks, roundabouts and tunnels. The sensors had different configuration parameters, suggested by the supplier, to avoid signal interference. With parameters as chosen, sensor ranges, inferred from maximum distance measurements, were approximately 74 and 71 m. These values were almost on par with theoretical calculations. The sensors captured the preceding truck for 83–85% of the time where they had the preceding truck within range, and 95–96% of the time in tunnels. While roundabouts are problematic, the sensors are feasible for collecting inter-vehicle distance data during truck platooning.

Automotive Radar in a UAV to Assess Earth Surface Processes and Land Responses.

The use of unmanned aerial vehicles (UAVs) in earth science research has drastically increased during the last decade. The reason being innumerable advantages to detecting and monitoring various environmental processes before and after certain events such as rain, wind, flood, etc. or to assess the current status of specific landforms such as gullies, rills, or ravines. The UAV equipped sensors are a key part to success. Besides commonly used sensors such as cameras, radar sensors are another possibility. They are less known for this application, but already well established in research. A vast number of research projects use professional radars, but they are expensive and difficult to handle. Therefore, the use of low-cost radar sensors is becoming more relevant. In this article, to make the usage of radar simpler and more efficient, we developed with automotive radar technology. We introduce basic radar techniques and present two radar sensors with their specifications. To record the radar data, we developed a system with an integrated camera and sensors. The weight of the whole system is about 315 g for the small radar and 450 g for the large one. The whole system was integrated into a UAV and test flights were performed. After that, several flights were carried out, to verify the system with both radar sensors. Thereby, the records provide an insight into the radar data. We demonstrated that the recording system works and the radar sensors are suitable for the usage in a UAV and future earth science research because of its autonomy, precision, and lightweight.

Analysis of the Potential Space Resolution in Multi-position Surface Movement Radar System

Specialized surface movement radar (SMR) systems for visual observations of the airfield are one of the mandatory systems ensuring the safety of flights and control service of aerodromes. Design of multi-position SMR systems comprising a set of simple and low-cost radar sensors (RS) is a promising trend. A problem to estimate a potential resolution in a multi-position SMR system is relevant.The paper describes two approaches to estimate the potential resolution using the "joint" ambiguity function, namely additive and multiplicative. Both approaches allow taking into account a type of the radar signal used, an antenna radiation pattern (ARP), and the location of radar sensors on the airfield.To implement the considered approaches to the resolution estimation, was used a software package to analyse the multi-position SMR system characteristics. For a particular example to locate radar sensors, the calculation results of the ambiguity function are given.The paper presents an estimated space resolution in the multi-position SMR system in Cartesian coordinate system. Draws conclusions about the possibility for obtaining the multi-position SMR system resolution that exceeds the resolution of a single radar sensor with the exception of the isotropic radiation pattern of radar sensor and the additive estimation method.The developed software package can be used to analyse and justify the following:- space resolution requirements to the radar sensor;- recommendations on the location of the radar sensors;- resolution of the multi-position SMR system space including a radar sensor with known characteristics.

The Analysis of the Experimental Data from Radar Sensor of Multi-Position Surface Movement Radar Systems for Estimation of Radar Resolution

Space resolution is one of the most important characteristics of radar systems. In multi-position surface movement radar (SMR) systems, resolution depends on the properties of radar sensors, their location and co-processing methods of radar data. The subject of experimental studies was a range and angular resolution of the X-band surface surveillance radar sensor as a part of the multi-position SMR system. The radar sensors were located on the airfield. The size of the range strobe to be analysed was 0.79 m, and the azimuth width was 1 0 . As to the radiation pattern width, the MRS-1000 does not satisfy the specialised SMR system requirements for 0.4 0 at most. The analysis objective was to estimate the range and angular resolution of radar sensors across maneuvering area of the artificially covered airfield surface and, using these data, give justification for further analysis of the multi-position SMR system characteristics. The paper describes a general technique to estimate the range and angular resolution of the radar sensor using a radar sensor and a pair of reference corner reflectors (RCR) with radar cross-section (RCS) of 1 m 2 and record the radar sensor output signals and provide their post-processing. The resolution was estimated by approximating the samples of the recorded signals with a Gaussian function using the least squares method. The results of range and angular resolution estimates are presented as follows: 1.5 ... 2 m in range, 1 ... 1.5 0 in azimuth. The relevance of the outcomes achieved is motivated by the need to conduct further analysis of the multi-position SMR system comprising relatively simple and low-cost radar sensors with characteristics, which are beneath the requirements for specialised SMR radars.

Dynamic and static structural displacement measurement using backscattering DC coupled radar

Vibration-based monitoring is one approach used to perform structural condition assessment. By measuring structural response, such as displacement, dynamic characteristics of a structure may be estimated. Often, the primary dynamic responses in civil structures are below 5 Hz, making accurate low frequency measurement critical for successful dynamic characterization. In addition, static deflection measurements are useful for structural capacity and load rating assessments. This paper presents a DC coupled continuous wave radar to accurately detect both dynamic and static displacement. This low-cost radar sensor provides displacement measurements within a compact, wireless unit appropriate for a range of structural monitoring applications. The hardware components and operating mechanism of the radar are introduced and a series of laboratory experiments are presented to assess the performance characteristics of the radar. The laboratory and field experiments investigate the effect of factors such as target distance, motion amplitude, and motion frequency on the radar\'s measurement accuracy. The results demonstrate that the radar is capable of both static and dynamic displacement measurements with sub-millimeter accuracy, making it a promising technology for structural health monitoring.

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.

Architecture of a multistatic FMCW direction-finding radar

The key technology of the future will be the use of low-cost sensor networks in order to replace large aperture antennas. The proposed multistatic radar system is composed of a transmitter, a number of receivers, dispersed in a lower altitude area, and a central processing station. Each receiver extracts the targets bistatic range and range-rate information, while estimating their azimuth angle. The receiver bistatic measurements, after local data processing, are sent to a central processing station, where three dimensional multiple target tracking is conducted. The main objective of the proposed multistatic radar system is to increase the detection probability of targets with low monostatic RCS, taking advantage of the Bistatic Radar Cross Section (BRCS) and the low operating frequency (low UHF band). Furthermore, the transmitter is only charged with the operation of emitting a Frequency Modulated Continuous Wave (FMCW) signal and an appropriate synchronization beacon, while the receiver performs a totally passive function. The main design objective is the use of a low cost radar sensor which performs an unsophisticated operation, while the main system functionality is accumulated in the central processing station.

An Efficient Method of Eliminating the Range Ambiguity for a Low-Cost FMCW Radar Using VCO Tuning Characteristics

This paper describes a simple method of eliminating the range ambiguity and the design approach for low-cost and small-size homodyne frequency-modulated continuous-wave (FMCW) radars. The range measurement accuracy could be efficiently improved by proper time gating of the beat signal without any closed-loop linearity compensation circuitry for typical varactor-tuned voltage-controlled oscillators (VCOs). The presented selectively gated fast Fourier transformation method is immune to the frequency shift of the VCOs. A W-band FMCW radar using a raw varactor-tuned VCO having the percent linearity of 7.16% was implemented, and achieved less than 2% ranging error of the target lying at 200 m. Owing to the simple structure and fast processing speed, this method is applicable to the various low-cost radar sensors for ranging and detection