Speed Measurement System Research Articles

Portable Roadside Sensors for Vehicle Counting, Classification, and Speed Measurement

This paper focuses on the development of a portable roadside magnetic sensor system for vehicle counting, classification, and speed measurement. The sensor system consists of wireless anisotropic magnetic devices that do not require to be embedded in the roadway-the devices are placed next to the roadway and measure traffic in the immediately adjacent lane. An algorithm based on a magnetic field model is proposed to make the system robust to the errors created by larger vehicles driving in the nonadjacent lane. These false calls cause an 8% error if uncorrected. The use of the proposed algorithm reduces this error to only 1%. Speed measurement is based on the calculation of the cross correlation between longitudinally spaced sensors. Fast computation of the cross correlation is enabled by using frequency-domain signal processing techniques. An algorithm for automatically correcting for any small misalignment of the sensors is utilized. A high-accuracy differential Global Positioning System is used as a reference to measure vehicle speeds to evaluate the accuracy of the speed measurement from the new sensor system. The results show that the maximum error of the speed estimates is less than 2.5% over the entire range of 5-27 m/s (11-60 mi/h). Vehicle classification is done based on the magnetic length and an estimate of the average vertical magnetic height of the vehicle. Vehicle length is estimated from the product of occupancy and estimated speed. The average vertical magnetic height is estimated using two magnetic sensors that are vertically spaced by 0.25 m. Finally, it is shown that the sensor system can be used to reliably count the number of right turns at an intersection, with an accuracy of 95%. The developed sensor system is compact, portable, wireless, and inexpensive. Data are presented from a large number of vehicles on a regular busy urban road in the Twin Cities, MN, USA.

Design of Wind Speed Measurement System Based on Integrated Navigation and Atmospheric Data Fusion

The characteristics wind field impact flight safety, trajectory keeping, and navigation performance of Micro Unmanned Aerial Vehicles (MUAV) directly. Accurate wind field measurement is a premise for MUAVs to take various pre-reactions to gust disturbance. Due to its small size, light weight, and low speed, MUAV is easily affected by gust disturbance during its flight at low altitude. Real time wind speed estimation and flight control strategy adjusting can reduce the impact of gust and enhance flight safety. This paper proposes a method of using airborne IMU, GPS, and pressure sensors to estimate wind speed. Experimental results show that this method can effectively estimate wind speed accurately, and has important application value.

Research on Speed Measurement System Based on DSP

Research on Speed Measurement System Based on DSP

Classification Research of Rotation Speed Measurement

Instantaneous speed measurement system can accurately measure the rotating target and realize the rotation direction judgment. It plays a very important role in industrial applications, as monitoring or controlling the rotation speed of transmitter, motor, turbine. With the development of technology, a modern speed measurement system is demanded to be intelligent, high integration, high precision, high reliability, and low cost etc. Based on the large number of literatures, this paper is a comprehensive review of the principle and application of domestic and foreign mature technology of rotation speed measurement method at present. Through the systematic classification, relationship between the different speed measurements is revealed, and the advantages and disadvantages of different measuring sensor are presented, so that readers can choose reasonable speed measurement method depending on the application, the actual measurement requirements and the test purposes.

The Rotational Speed Measurement of Brushless DC Motor Based on STM32 Microcontroller

The brushless DC motor applied on the electric steering gear of trajectory correction projectiles often requires getting real-time rotational speed value. The hall sensors output the hall signals for measurement, after the integration by the D-type flip-flop, an ideal pulse can be produced. Afterwards STM32F103ZE microcontroller is used to calculate the rotational speed value of the motor by the Improved M/T method. The resolution and precision can be analyzed after getting the result. This rotational speed measurement system has high precision and good real-time characteristics. It is significant for the meaning of the correction of the steering gear.

Non-destructive evaluation of grain angle, moisture content and density of spruce with microwaves

Non-destructive evaluation of the physical properties of wood is a key task in modern wood manufacturing processes. Due to a rapidly increasing production speed, fast, non-contacting, reliable and robust measurement systems are demanded by the wood industry. Common moisture meters are able to reasonably cope with industrial needs. However, modern detection of wood grain angle deviation remains an unresolved issue. Microwave technology features the ability to simultaneously identify grain angle, density and moisture content of wood by measuring attenuation, phase shift, and depolarization of transmitted signals. This paper reports on series of microwave measurements revealing the desired physical properties for spruce. Samples were tested at different frequencies in the range from 8 to 12 GHz. For each frequency the grain angles were identified with standard errors of maximum 0.15° (measuring range from −90° to +90°). Standard errors in the determination of moisture density were less or equal 1.8 kg/m³ (measuring range from 27 to 56 kg/m³). Standard errors determining moisture content were maximum 0.47 % (measuring range from 7.6 to 14 %), and standard errors for dry density were maximum 11.3 kg/m³ (measuring range from 284 to 492 kg/m³).

Design of Rotational Speed Measurement System Based on the Hall Sensor

This paper introduces a design of a STC89C52 microcontroller as the main controller, the motor speed is measured by the Hall sensor. This design uses integrated Hall sensor, which has a frequency response, high precision and anti-interference ability. This article describes the working principle of the method and method of use of the Hall sensor measurement speed

Ballistic parameters of .177 (4.5 mm) caliber plastic-sleeved composite projectiles compared to conventional lead pellets

The capability of conventional air gun lead pellets (diabolo pellets) to cause severe injuries or fatalities even at low kinetic energy levels is well documented in medical literature. Modern composite hunting pellets, usually a metal core (made of steel, lead, zinc, or a zinc and aluminum alloy) encased in a plastic sleeve, are of special forensic and traumatological interest. These projectiles are advertised by the manufacturers to discharge at higher velocities than conventional air gun pellets, thus generating very high tissue-penetrating capabilities. Lack of experimental data on these uncommon air gun projectiles induced this work. Ballistic parameters of 12 different caliber .177 (4.5mm) composite pellets, discharged from two spring-piston air guns (Weihrauch HW 35, Webley CUB) and three pneumatic air guns (Walther LGR, Walther LG400, Walther LP300), were investigated using a ballistic speed measurement system and compared to a conventional diabolo pellet (RWS Meisterkugel) as reference projectile. Although overall results were inconsistent, for some projectile-weapon combinations (particularly spring-piston air guns), a significant change of the kinetic energy (-53 up to +48%) to the reference projectile was observed. The data provided in this work may serve as a basis for forensic investigation as well as traumatological diagnosis and treatment of injuries caused by these uncommon projectiles.

Accuracy and Characteristics of 2012 Honda Event Data Recorders from Real-Time Replay of Controller Area Network (CAN) Traffic

Prior EDR testing methodologies required setting events in the airbag control module in the vehicle during controlled driving behavior. Duplicating events was nearly impossible, and it was difficult to separate how much differences in recorded speeds to reference speeds was due to measurement error, wheel slip, reporting time delays, or data truncation within the EDR. Recording thresholds have also increased making non-deployment and deployment events closer in magnitude, increasing the risk of accidentally exceeding the deployment threshold while setting events. The new methodology eliminates the risk of accidentally deploying airbags while gathering GPS and CAN bus data in the test vehicle. The techniques presented in this paper also allows gathering of data in vehicle without tampering with the airbag control module, which reduces the potential liability to testers using rental or borrowed test vehicles. The new methodology allows for repeatable testing and mapping the transfer function between the vehicle CAN bus data and the EDR. Should a manufacturer make a design change to an ACM EDR, identical inputs can be given to exemplar ACM's from before and after the changes to document any change in the transfer function. This methodology allows researchers the ability to re-create events of interest in a low-cost, repeatable manner. The accuracy of the 2012 Honda CR-V and 2012 Honda Civic event data recorders were tested using this new two part methodology. First, the test vehicles were instrumented with both a Racelogic VBOX differential GPS speed measurement system and a Vector CAN data logger. The measurements from the VBOX were transmitted onto the vehicle's Controller Area Network (CAN) bus that also contained messages reflecting indicated vehicle speed, brake status, accelerator pedal position, steering wheel angle, individual wheel speeds and other signals. This put the GPS speed data on the same time base as the vehicle CAN speed signal such that no additional synchronization was required. This permitted analysis of the accuracy and update rate of the vehicle speed CAN signal, which is the source for speed data used in the Event Data Recorder (EDR). Second, a system was developed to replay the recorded CAN data to an exemplar airbag control module in the laboratory, such that the exemplar was receiving data exactly as if it were in a moving vehicle. A pneumatic fixture with a slide was built to allow the exemplar module to be accelerated to nearly 10 km/h (6 mph) and then stopped in about 80 msec. to create a non-deployment event that met the minimum 5 mph delta-V over 150ms threshold. Actuation of the event setting fixture was computer controlled (using LabVIEW) and synchronized with the CAN replay system so that the desired test condition could be replicated precisely. An external accelerometer was mounted to the airbag control module to mark when the ACM began recording and the accelerometer data was matched to the acceleration and delta-V data in the EDR. The desired test conditions were replayed to the airbag control module and a series of non-deployment events were set. Each event on the EDR data was read using the Bosch Crash Data Retrieval system. The EDR data was compared to the inputs, and it was determined that the two byte vehicle CAN bus signal was truncated to the next lower whole km/h when recorded in the EDR. Under steady state conditions the speed data was accurate within 2%. The vehicle CAN signal published new values every 0.1 seconds, and the CR-V updated values every 0.1 seconds, but the Civic only updated every 0.6 seconds during hard brake events. During hard ABS braking events the expected wheel slip led to the vehicle speed signal under-reporting ground speed, but the delay in the CAN bus update rate resulted in over-reporting ground speed in many of the tests. Language: en

A Research of High Precision Rotational Speed Measurement System Based on Infrared Sensor and Microcontroller

With the deep analysis on the rotational speed measurement and the error existed in the measurement process at present, this paper introduces a high precision rotational speed measurement system based on infrared sensor and microcontroller. This system combines with improved measuring method. The sensor is an infrared photoelectric sensor, and uses its characteristics of the autocollimator ensured accuracy of measurement. The photoelectric sensor outputs weak voltage pulse signal when it receives the reflected infrared light. And then the signal is processed by double-reversed amplification and twice pulse shaping circuit. The system uses the relevant logic functions of a D-type flip-flop to control two 16-bit microcontroller chip timing/counter turned on and off simultaneously, and calculates the rotation speed. At last, the result is displayed on LED by Microcontroller. This measurement system has high accuracy, fast sampling speed and wide measuring range.

Ballistic parameters and trauma potential of pistol crossbows

Hand-held pistol crossbows, which are smaller versions of conventional crossbows, have recently increased in popularity. Similar to conventional crossbows, life threatening injuries due to bolts discharged from pistol crossbows are reported in forensic and traumatological literature. While the ballistic background of conventional crossbows is comprehensively investigated, there are no investigations on the characteristic ballistic parameters (draw force, potential energy, recurve factor, kinetic energy, and efficiency) of pistol crossbows. Two hand-held pistol crossbows (Barnett Commando and Mini Cross Bow, rated draw force 362.9N or 80lbs) were tested. The maximum draw force was investigated using a dynamic tensile testing machine (TIRAtest 2705, TIRA GmbH). The potential energy was determined graphically by polynomial regression as area under the force-draw curve. External ballistic parameters of the bolts discharged from pistol crossbows were measured using a redundant ballistic speed measurement system (Dual-BMC 21a and Dual-LS 1000, Werner Mehl Kurzzeitmesstechnik). The average maximum draw force was 190.3 and 175.6N for the Barnett and Mini Cross Bow, respectively. The corresponding total energy expended was 10.7 and 11J, respectively. The recurve factor was calculated to be 0.705 and 1.044, respectively. Average bolt velocity was measured 43 up to 52m/s. The efficiency was calculated up to 0.94. To conclude, this work provides the pending ballistic data on this special subgroup of crossbows which operate on a remarkable low kinetic energy level. Furthermore, it demonstrates that the nominal draw force pretended in the sales brochure is grossly exaggerated.

Output Power Leveling Control of WECS Based on Extended State Observer for All Operating Regions

This paper designs the pitch controller synthesis to ensure the stability and the controllability in the whole regions as the power grid scheduling instructions. Because of the wind speed measurement and accurate system model are hard to obtain, the range that the actual working point deviating from the balance point is very large, so that the system dynamic performance cannot be described with linear time variable (LTI). This paper utilizes the linear matrix inequalities' techniques (LMI) to design LPV (linear parameter varying) gain-scheduled controllers based on criteria, which provide guarantees of stability performances along the whole reference trajectory. The LPV pitch controller replaces the traditional speed controller to dynamically compensate the pitch angle. According to the errors between the power grid scheduling instructions and measuring the output power, power controller adjusts generator torque to achieve the adjustable power in the whole regions. In view of unmodeled dynamics and wind speed random disturbance, the feed forward linearization. robust pitch regulation using extended state observer (ESO) is proposed to restrain comprehensive disturbances. The proposed controller is seen to be more efficient.

Evaluation of Ti-Zr-V (NEG) Thin Films for their pumping speed and pumping Capacity

Deposition of NEG thin films onto the interior walls of the vacuum chambers is an advanced technique to convert a vacuum chamber from a gas source to an effective pump. These films offer considerably large pumping speed for reactive gases like CO, H2 etc. A UHV compatible pumping speed measurement system was developed in-house to measure the pumping speed of NEG coated chambers. To inject the fixed quantity of CO and H2 gas in pumping speed measurement set-up a calibrated leak was also developed. Stainless steel chambers were sputter coated with thin film of Ti-Zr-V getter material using varied parameters for different compositions and thickness. Pumping capacity which is a function of sorbed gas quantities was also studied at various activation temperatures. In order to optimize the activation temperature for maximum pumping speed for CO and H2, pumping speeds were measured at room temperature after activation at different temperatures. The experimental system detail, pumping performance of the NEG film at various activation temperatures and RGA analysis are presented.

Improvement of Wind Speed Measurement Model by Meteorological UAV and System Design

At present, the error of wind speed measurement by meteorological UAV is great, in order to solve this problem, this paper identified the major sources of error by the analysis of the wind measurement model. Found that the airspeed error caused by the aircraft acceleration for the airspeed is very small, so classic airspeed measurement calculations often ignore the impact of aircraft acceleration, but the value of wind speed is smaller, so that the error caused by aircraft acceleration relative to the wind speed cannot be ignored. Therefore, this article added aircraft acceleration to re-establish the airspeed measurement model, and got an improved wind speed of calculation model. In order to verify the model, the wind speed measurement system was been designed, the system design diagram and related data processing, solver method were presented.

Vehicle Speed Meters Validation and Verification System

Speed meters verification principles and problems are observed in the article. Method of vehicle average speed measurement over the specified length road segment was proposed, using four laser units. The method allows to avoid synchronization between measurements of speed meter under metrological test and reference system during verification procedure and therefore to avoid vehicle speed variation influence. Developed reference speed measurement system has expanded uncertainty less than ±0.3 km/h, including vehicle speed variation term. Ill. 3, bibl. 8 (in English; abstracts in English and Lithuanian).DOI: http://dx.doi.org/10.5755/j01.eee.119.3.1372

저속풍동 시험부 속도교정에 관한 실험적 연구

The purpose of this research is to determine the calibration constants of the wind speed measurement systems required to calculate the wind tunnel velocity in the test section. In the present work, the aerodynamic calibration tests of the test section were conducted in the Agency for Defense Development`s Low-Speed Wind Tunnel. The test speed ranged from 10 to 100 m/s with a reference pitot-static pressure probe. The validity of the calibration results was evaluated by comparing them with the previous calibration constants. The calibration results show that fair to good agreement is obtained with resonable accuracy.

Time Delay Estimation Algorithm Used in Ultrasonic Wind Speed Measurement System

In this work, the application of time delay estimation in ultrasonic wind speed measurement system is discussed. The algorithm of time delay estimation based on least mean square (LMS) adaptive noise cancellation of generalized correlation with fixed ultrasonic is presented. The algorithm uses LMS daptive filter to eliminate the noise interference efficiently and does not need to know prior-knowledge of signal and noise. Then, it uses generalized correlation to estimate the time delay. Computer simulation and practical test results show that the algorithm can effectively eliminate noise. The wind speed estimation accuracy is very high; so the algorithm can be used for monitoring the low-level wind field at airport regional.

S051043 風車後流に与えるロータ負荷条件に関するフィールド実験

In wind farms which mean many wind turbines constructed in a site, the wind passed through an upstream wind turbine (i.e., wind turbine wake) flows in a downstream wind turbine. As a result, the wake causes power reduction and fatigue load on the downstream wind turbine. Therefore, it is important to clarify the characteristics of wind turbine wake. In this study, by using a test wind turbine and wind speed measurement systems, the wind speed distribution in the wake were measured in non-yawed and yawed conditions in field and the effects of yawed inflow on the wake characteristics were clarified. A gaussian wake model for non-yawed and yawed conditions was investigated and compared with the experimental results.

A speed measurement system utilizing an injection-seeded Tm:YAG laser

A speed measurement system utilizing a stable single frequency Q-switched Tm:YAG laser was presented in this study. The maximum pulse energy of the laser was 2.38 mJ with the pulse repetition rate of 100 Hz. Using the speed measurement system, the revolving speed of a rotating target could be measured by optical heterodyne detection technique and the maximum measurement error was 0.68 m/s.

The Model and Algorithm of Doppler Radar Speed Measurement System <sup></sup>

Based on the measurement of train speed, this paper briefly describes the basic principle of Doppler speed measurement and the design of speed measurement system. By the analysis of test signal which simulates the actual speed signal and comparison of the simulation results, the AR power spectrum estimation algorithm is selected as the model of speed measurement system, and the Burg method is selected to evaluate the Doppler frequency. Then the effect of parameters such as sampling frequency, length of the input vector, FFT length and estimation order on power spectrum estimation are analyzed, the optimization principles of the parameters are defined. Finally, the determined method is simulated with a high-noise, multi-jamming signal and has good results. The accuracy, stability and immunity are proved by the simulation.