Mass Flow Sensor Research Articles

Elimination of vibration noise from an impact-type grain mass flow sensor

Intensive vibration caused by uneven field terrain and imbalance of working components in a combine harvester is commonly experienced by yield monitors, causing a significant influence on the performance of impact-type grain flow sensors. A yield monitor test stand was constructed based on a commercial combine harvester, and a method was developed to eliminate the effects of vibration disturbance on impact-type flow sensors. The vibration caused by combine harvesters was simulated well in the experiment, and moreover the actual grain flow rate could be adjusted and measured precisely by the weighing sensors fixed under the grain feed tank in real time. An impact-type grain flow sensor was manufactured using two parallel-beam load cells: one was impacted by the grain flow, and the other was applied as a reference beam that was only excited by the vibration of the sensor frame. A harmonic extraction method was introduced to exploit the essential characteristics involved in the collision process between the grain and the impact plate driven by the elevator paddles of the combine harvester. Then adaptive interference cancellation was utilized to eliminate the vibration noise from the measurement of the impact force of the grain flow according to data from the reference parallel-beam load cell. The experimental results showed that the relative error was less than 2.2 % when the reference parallel-beam load cell was used alone, and relative error was reduced further to less than 1.6 % when both the data from the reference load cell and the harmonic extraction method were applied.

Research on a Flow Resistance Mass Flow Sensor

A flow resistance mass (momentum) flow sensor has been designed. The structure and principle of flow sensor are introduced. The testing results show that the flow sensor is excellent in stain resistance, large flow ratio, low power dissipation and long service life. A heatmeter can be achieved using the designed sensor with matching integer operation and display modules.

Volumetric mass flow sensor for citrus mechanical harvesting machines

A volume-based mass flow sensor system was developed to estimate the total mass of fruit travelling on the inclined and horizontal conveyors of two citrus mechanical harvesting systems. A LIDAR (light detection and ranging) sensor was used to scan the conveyor cross-sectional area and use the distance related-information to estimate the bulk volume and total mass of fruit on the conveyor by integrating the data over time. A custom algorithm was developed to analyze the data and calculate the fruit volume. Fruit volume was used to estimate the total fruit mass.Sensor system was tested in the laboratory on two different conveyor systems: an inclined conveyor used in a mechanical harvester (conveyor flap height=8cm), and a horizontal conveyor used in a debris removal system (conveyor flap height ⩽3cm). The tested conveyor speeds ranged from 0.59m/s to 1.71m/s. The system performance for the tested speed ranges was an average error of 7% (standard deviation [SD]±7%) and 7% (SD±5%) for the inclined and horizontal conveyors, respectively. The average total fruit mass estimation error during mechanical harvesting was 10% (SD±6%) for 11 field trails that involved scanning 512–1356kg of the fruit on a horizontal conveyor of a debris removal system. Overall, the developed sensor system can be used for volumetric yield monitoring of citrus. The sensor system performance will likely be improved using instant conveyor speed during the estimation of total fruit mass.

Modeling Influence of Tube Material on Vibration based EMMFS Using ANFIS

The modeling of a vibration based electromechanical mass flow sensor using an adaptive neuro-fuzzy inference system (ANFIS) has been presented to study the influence of tube material. The input parameters taken into consideration are tube material, sensor location, drive frequency, height of tube. The results show that a well trained and well tested ANFIS model has the capability to predict the performance of mass flow sensor under varying operational conditions depending on the availability of the data and can be used as an alternative to the physical models in the sense that the results can be produced in a fast and cost effective way. The performance of the model in regions where deficiency of data exists has been discussed.

Estimation of in-cylinder mass and AFR by cylinder pressure measurement in automotive Diesel engines

Abstract In the last decades the role of the engine control has became fundamental to improve fuel consumption and comply with the emissions standards. Particularly on automotive Diesel engines sophisticated control systems have been introduced, which are based on both large measurement data sets and complex controllers. Alternatives are needed to simplify and improve the Engine Management System (EMS). To this purpose the in-cylinder signal may be an effective measure to enhance EMS and its reliability, as well as to potentially reduce both costs and development time. The paper deals with the development of two techniques to estimate the Air-Fuel Ratio (AFR) and the in-cylinder mass from the in-cylinder pressure signal. These methodologies are intended to be implemented in real-time with the aim of replacing or working jointly with the existing air mass flow and lambda sensors. The techniques were validated vs. experimental data measured at the engine test bench on a Common Rail light-duty Diesel engine. The results show a good accuracy in predicting Air-Fuel Ratio and in-cylinder mass in a wide engine operating range.

ANN Modelling of Cu Type Omega Vibration Based Mass Flow Sensor

Abstract Artificial neural network (ANN) based model has been developed for copper omega type mass flow sensor. The significant phase shift parameter is modeled for various input factors like sensor location, drive frequency, mass flow rate and length of tube. This model is found in good agreement with the experimental results after comparison. The effectiveness of the ANN model was tested with test data. The correlation coefficient(R) between the predicted phase shift and the experimental phase shift for training, validation and test data was found to be acceptable for prediction of phase shift by taking sensor location, mass flow rate, length of tube and frequency excitation as input parameters. A reliable and useful predictor for phase shift for future studies in Cu type mass flow sensor may be developed based on large number of variables used during training the model.

High Precision Bidirectional Heat Pulsed Flow Sensor

In this work we have designed and simulated a thermal bi-directional integrated circuit mass flow sensor. The approach used here was an extension to the gas flow model given by Mayer and Lechner [1]. The design features high precision response received from analog integrated circuits. An established mathematical model for the heat flow equation including CFD parameters were used within COMSOL simulation (COMSOL Multiphysics, Sweden). Heat pulses of 55°C for a period of nearly 120 seconds and 50% duty cycles were applied as thermal sources to the flowstream. The boundary conditions of the heat equations at the solid (heating element) fluid interface were set up in the software for the thermal response. The hardware design included one heating element and two sensing elements were used to detect the bi-directional mass flow. Platinum sensors were used due to their linear characteristics within 0°C to 100°C range, and their high temperature coefficient (0.00385 Ω/°C). Polyimide thin film heater was used as the element due to its high throughput and good thermal efficiency. Two bridge circuits were used to sense the temperature distribution in the vicinity of the sensing elements.

Novel mass air flow meter for automobile industry based on thermal flow microsensor. II. Flow meter, test procedures and results

A prototype of mass air flow meter for automobile industry was developed on the basis of thermal flow microsensor. Design and manufacturing technology of the flow meter are described. Test procedure and results are presented. Developed prototype of flow meter can diagnose gas flow rates in a wide range.

Transient Fuel Injection Rate and Fuel Economy Prediction for a Vehicle Driven with FTP-75 Mode Using an ECU HILS

A fuel injection system which is operated with ECU HILS was used to evaluate the transient fuel injection rate and fuel economy. Several sensor signals from a car such as the engine speed, car speed, cam position, crank position, air mass flow, throttle position and several other sensor signals are measured and recorded as a data file with DAQ-system for a vehicle driven in FTP-75 mode in a chassis dynamometer. Electric signals that are equivalent to the sensor signals from the car are reconstructed from the recorded data file using DAQ boards and a computer. All the reconstructed sensor signals are provided to the ECU with synchronized timing. Injectors were connected to the ECU output pins and were driven by the system to measure the quantity of injected fuel. The ECU HILS show that the transient fuel injection rate and fuel economy for the car driving mode could be successfully predicted. Also, the repeatability of the generation of sensor signals can enhance the accuracy of a range of experiments related to cars fuel injection experiment.

AFR-Based Fuel Ethanol Content Estimation in Flex-Fuel Engines Tolerant to MAF Sensor Drifts

Flexible fuel vehicles (FFVs) can operate on a blend of ethanol and gasoline in any volumetric concentration of up to 85% ethanol (93% in Brazil). Existing FFVs rely on ethanol sensor installed in the vehicle fueling system, or on an ethanol estimation based on air-to-fuel ratio (AFR) regulation via an exhaust gas oxygen (EGO) or λ sensor. The EGO-based ethanol detection is desirable from cost and maintenance perspectives but it is known to be prone to large errors during mass air flow sensor drifts. Ethanol content estimation can be realized by a feedback-based fuel correction of the feedforward-based fuel calculation using an exhaust gas oxygen sensor. When the fuel correction is attributed to the difference in stoichiometric air-to-fuel ratio (SAFR) between ethanol and gasoline, it can be used for ethanol estimation. When the fuel correction is attributed to a mass air flow (MAF) sensor error, it can be used for sensor drift estimation and correction. Deciding under which condition to blame (and detect) ethanol and when to switch to sensor correction burdens the calibration of FFV engine controllers. Moreover, erroneous decisions can lead to biases in ethanol estimation and in MAF sensor correction. In this paper, we present AFR-based ethanol content estimation, associated sensitivity and dynamical analysis, and a cylinder air flow estimation scheme that accounts for MAF sensor drift or bias using an intake manifold absolute pressure (MAP) sensor. The proposed fusion of the MAF, MAP, and λ sensor measurements prevents severe misestimation of ethanol content in flex fuel vehicles.

A Novel Fiber-Optic Mass Flow Sensor

In this paper a novel fiber-optic mass flow sensor based on coriolis force is presented. As sensing elements two fiber-optic curvature sensors mounted on elastic rubber tube are used. Rubber tube with sensing elements is excited by stepper motor. Produced system has the option of varying angle and speed of excitation. The bending of the fibers at the sensitive zone on curvature sensor changes the intensity of light traveling through the optical fiber. Curvature sensors are attached to the rubber tube so that they can measure phase difference produced by coriolis force. Mass flow rate is obtained by digital signal processing technique for phase difference detection.

Novel mass air flow meter for automobile industry based on thermal flow microsensor. I. Analytical model and microsensor

An analytical model of the thermal flow sensor has been developed. The results of analytical model application are utilized to develop a thermal flow microsensor with optimal functional characteristics. The technology to manufacture the microsensor is described. A prototype of the microsensor suitable to be used in the mass air flow meter has been designed. The basic characteristics of the microsensor are presented.

INTEGRATED MASS AIR FLOW SENSOR AND BROADBAND SILENCER

An integrated mass air flow sensor/broadband silencer assembly comprises a molded body having a plurality of walls formed therein. The molded body is over-wrapped with a layer of acoustic foam that, together with the plurality of walls, define a plurality of chambers within an interior volume of the assembly. A mass air flow sensor can be inserted into one of the chambers. The chambers are sized and spaced to provide a uniform velocity, low turbulence air flow to the sensor, and a minimally-restricted air flow to an internal combustion engine located downstream of the assembly.

Mass-Flow Estimation in Mineral-processing Applications

This paper evaluates mass-flow estimation capabilities of four online mass-flow sensors: Power transducer, laser profilometer, ultrasonic sensor, and strain gauge. Mass-flow estimates are generated with two methods, linear-regression and non-linear physical mass-flow estimation models. The results of this work indicate very good mass-flow estimation capabilities for all of the sensor types. These accurate and cost-effective mass-flow sensors increase online monitoring capabilities in the mineral-processing plants significantly, also allowing more effective manual process control, as well as the development and implementation of more advanced automatic process control and optimisation systems. However, a reference mass-flow measurement needs to be available for the calibration of the sensors.

Output Drifting of Vacuum Packaged MEMS Sensors Due to Room Temperature Helium Exposure

Exposure of absolute pressure sensors, resonant microtube density, binary concentration sensors and chip-scale vacuum packaged pirani gauges to room temperature helium resulted in a gradual drift in sensor output. No effect was found for differential pressure sensors and pirani gauges vacuum packaged with ceramic or metal packages. The observed results apply to other vacuum packaged MEMS devices such as gyroscopes, voltage controlled oscillators, infrared and Coriolis mass flow sensors. Potential causes for this loss of hermeticity are discussed as well as application limitations for MEMS sensors.

Flow Microsensor of Thermal Type for Measurements of Gas Fluxes

An analytical model of the flow sensor of thermal type is developed. The results of the model application are used to develop a flow microsensor of thermal type with optimal functional characteristics. The technology of microsensor manufacturing is provided. The prototype of the microsensor suitable for use in the mass air flow meter is created. The basic characteristics of the microsensor are presented.

Development of sensor systems for precision agriculture in cotton

Precision agriculture (PA) is an information-based technology, using detailed information within an agricultural field to optimize production inputs on a spatially variable basis, maximize farm profit, and minimize environmental impact. Information collection and processing plays a very important role in PA. In recent years PA technologies have been gradually adopted in cotton production. Several sensor systems for PA were developed and field-evaluated in cotton, including a plant height measurement system (PHMS), the Mississippi cotton yield monitor (MCYM), and cotton fiber quality mapping. The PHMS used an ultrasonic sensor to scan the plant canopy and determine plant height in real time in situ. A plant height map was generated with the data collected with the PHMS. Cotton plant height showed a close relationship with yield (R2=0.63) and leaf-nitrogen content (R2=0.48). The MCYM was developed for cotton yield mapping. A patented mass-flow sensor technology was employed in the MCYM. The sensor measured optical reflectance of cotton particles passing through the sensor and used the measured reflectance to determine cotton-mass flow rates. Field tests indicated that the MCYM could measure cotton yield with an average error less than 5%, and it was easy to install and maintain. The cotton fiber-quality mapping research involved a wireless cotton module-tracking system (WCMTS) and a cotton fiber quality mapping system (CFQMS). The WCMTS was based on the concept that a cotton fiber-quality map could be generated with spatial information collected by the system during harvesting coupled with fiber quality information available in cotton classing offices. The WCMTS was constructed and tested, and it operated according to design, with module-level fiber-quality maps easily made from the collected data. The CFQMS was designed and fabricated to perform real-time measurement of cotton fiber quality as the cotton is harvested in the field. Test results indicated that the sensor was capable of accurately estimating fiber micronaire in lint cotton (R2=0.99), but estimating fiber quality in seed cotton was more difficult. Cotton fiber quality maps can be used with cotton yield maps for developing field profit maps and optimizing production inputs.

Parametric excitation of a micro Coriolis mass flow sensor

We demonstrate that a micro Coriolis mass flow sensor can be excited in its torsional movement by applying parametric excitation. Using AC-bias voltages for periodic electrostatic spring softening, the flow-filled tube exhibits a steady vibration at suitable voltage settings. Measurements show that the sensor for this type of excitation can be used to measure water flow rates within a range of 0 ± 500 μl/h with an accuracy of 1% full scale error.

Novel Air Flow Meter for an Automobile Engine Using a Si Sensor with Porous Si Thermal Isolation

An air flow meter for measuring the intake air of an automobile engine is presented. It is based on a miniaturized silicon thermal mass flow sensor using a thick porous Si (Po-Si) layer for local thermal isolation from the Si substrate, on which the sensor active elements are integrated. The sensor is mounted on one side of a printed circuit board (PCB), on the other side of which the readout and control electronics of the meter are mounted. The PCB is fixed on a housing containing a semi-cylindrical flow tube, in the middle of which the sensor is situated. An important advantage of the present air flow meter is that it detects with equal sensitivity both forward and reverse flows. Two prototypes were fabricated, a laboratory prototype for flow calibration using mass flow controllers and a final demonstrator with the housing mounted in an automobile engine inlet tube. The final demonstrator was tested in real life conditions in the engine inlet tube of a truck. It shows an almost linear response in a large flow range between –6,500 kg/h and +6,500 kg/h, which is an order of magnitude larger than the ones usually encountered in an automobile engine.

The Design of Novel Thermal Gas Mass Flowmeter

Aiming at the defects of current thermal mass flow sensor, we developed a novel thermal gas mass flowmeter based on the principle of constant power, which consists of semiconductor sensors and a microcontroller as the core controller. The design plan is carried out on the basis of simple structure and reasonable cost, which maximizes accuracy and reliability of the flowmeter. The experimental results verify that the flow meter is running well and achieves the overall performance goals of the plan.