Ultrasonic Displacement Sensor Research Articles

A laboratory study of the effect of varying beach slopes on bore-driven swash hydrodynamics

Swash zone hydrodynamics has significant coastal geomorphological and engineering implications. However, there is still a research gap in fully understanding the response of bore-driven swash hydrodynamics to varying beach slopes. Therefore, in this study, laboratory experiments were performed in a flume to investigate the hydrodynamics of bore-driven swash flows over impermeable smooth beaches with a mild slope (1:35), a steep slope (1:10), and a composite slope (1:35–1:10), respectively. The designed swash events are produced by a collapse of dam-break-generated bores. Wave gauges, ultrasonic displacement sensors, acoustic Doppler velocimeter, and particle image velocimetry are used simultaneously to capture different phases (bore collapse, uprush, and backwash) of bore evolution in the entire swash zone. The impacts of beach slope on the swash hydrodynamics in view of the shoreline movement, swash depth, and swash velocity are first analyzed. The formation and evolution of the vortex structure on the three beaches are also reported in this study.

Concrete Crack Identification Using a UAV Incorporating Hybrid Image Processing.

Crack assessment is an essential process in the maintenance of concrete structures. In general, concrete cracks are inspected by manual visual observation of the surface, which is intrinsically subjective as it depends on the experience of inspectors. Further, it is time-consuming, expensive, and often unsafe when inaccessible structural members are to be assessed. Unmanned aerial vehicle (UAV) technologies combined with digital image processing have recently been applied to crack assessment to overcome the drawbacks of manual visual inspection. However, identification of crack information in terms of width and length has not been fully explored in the UAV-based applications, because of the absence of distance measurement and tailored image processing. This paper presents a crack identification strategy that combines hybrid image processing with UAV technology. Equipped with a camera, an ultrasonic displacement sensor, and a WiFi module, the system provides the image of cracks and the associated working distance from a target structure on demand. The obtained information is subsequently processed by hybrid image binarization to estimate the crack width accurately while minimizing the loss of the crack length information. The proposed system has shown to successfully measure cracks thicker than 0.1 mm with the maximum length estimation error of 7.3%.

Effect of Slope Angle on Seismic Response of Unreinforced and Reinforced Soil Slopes in Shaking Table Tests

This paper studies the effect of slope angle on the seismic response of unreinforced and reinforced soil slopes through a series of laboratory shaking table tests. Slopes were constructed using clayey sand and geogrids were used for reinforcing the slopes. The slope angle varies from 45°, 60° and 75° in different tests and the quantity and location of reinforcement is varied in different tests. Acceleration of base shaking varies from 0.1 to 0.3 g in the model tests and the frequency of base shaking was 2–10 Hz in different tests. The slope is instrumented with ultrasonic displacement sensors and accelerometers at different elevations. The response of different slopes is compared in terms of the horizontal displacements of the slope and acceleration amplifications measured at different elevations. At all frequency levels and base acceleration conditions, unreinforced slopes showed higher acceleration amplifications and increased displacements with the increase in steepness It was also observed from the test results that increase in steepness of the slope has detrimental effects on both acceleration amplifications and displacement response of unreinforced as well as reinforced model soil slopes.

Development of Compact Flexible Displacement Sensors Using Ultrasonic Sensor for Wearable Actuators

In position control of wearable actuator such as a rubber artificial muscle, a compact flexible displacement sensor is much attractive and required. In this paper, two types of flexible displacement sensor using the ultrasonic sensor were introduced. One is a built-in displacement sensor for rubber artificial muscle. Another is a sensor that can measure the sliding displacement on a flexible tube for flexible robot. Both sensors use ultrasonic displacement sensors. The construction, operating principle and measuring performance of two sensors were also described.

Seismic response of reduced-scale modular block and rigid faced reinforced walls through shaking table tests

This paper focuses on understanding the seismic response of geosynthetic reinforced retaining walls through shaking table tests on models of modular block and rigid faced reinforced retaining walls. Reduced-scale models of retaining walls reinforced with geogrid layers were constructed in a laminar box mounted on a uniaxial shaking table and subjected to various levels of sinusoidal base shaking. Models were instrumented with ultrasonic displacement sensors, earth pressure sensors and accelerometers. Effects of backfill density, number of reinforcement layers and reinforcement type on the performance of rigid faced and modular block walls were studied through different series of model tests. Performances of the walls were assessed in terms of face deformations, crest settlement and acceleration amplification at different elevations and compared. Modular block walls performed better than the rigid faced walls for the same level of base shaking because of the additional support derived by stacking the blocks with an offset. Type and quantity of reinforcement has significant effect on the seismic performance of both the types of walls. Displacements are more sensitive to relative density of the backfill and decrease with increasing relative density, the effect being more pronounced in case of unreinforced walls compared to the reinforced ones. Acceleration amplifications are not affected by the wall facing and inclusion of reinforcement.

Performance investigation of an advanced tracked prime mover on the low bearing soil

This study has presented a performance investigation of an advanced tracked prime mover for the operation of agricultural goods and other operations on peat terrain. The maximum and continuous traction torque of the prime mover has been developed by designing an advanced controller for controlling the intelligent system. The prime mover’s mobility is studied with ultrasonic displacement sensor, torque transducer, National Instrument cRIO-9004 Compact-RIO Real-time Controller Unit (RCU), a National Instrument TPC 2106T Touch Panel Control (TPC), a Trimble AG132 GPS antenna and receiver unit, and a Dlink DIR-655 router. The fuzzy logic controller (FLC) has been equipped with the prime mover hydraulic system to increase the traction torque of the hydraulic motor when the prime mover’s sinkage is more than or equal to 70mm. The prime mover’s design demonstrates good potential in traversing peat terrain as the measured tractive effort was found to be 48% of the vehicle’s gross weight while the recommended tractive effort is in the range of 30–36% of the vehicle’s gross weight.

Effect of frequency on seismic response of reinforced soil slopes in shaking table tests

This paper studies the effect of frequency of base shaking on the dynamic response of unreinforced and reinforced soil slopes through a series of shaking table tests. Slopes were constructed using clayey sand and geogrids were used for reinforcing the slopes. Two different slope angles 45° and 60° were used in tests and the quantity and location of reinforcement is varied in different tests. Acceleration of shaking is kept constant as 0.3 g in all the tests to maximize the response and the frequency of shaking was 2 Hz, 5 Hz and 7 Hz in different tests. The slope is instrumented with ultrasonic displacement sensors and accelerometers at different elevations. The response of different slopes is compared in terms of the deformation of the slope and acceleration amplifications measured at different elevations. It is observed that the displacements at all elevations increased with increase in frequency for all slopes, whereas the effect of frequency on acceleration amplifications is not significant for reinforced slopes. Results showed that the acceleration and displacement response is not increasing proportionately with the increase in the frequency, suggesting that the role of frequency in the seismic response is very important. Reinforced slopes showed lesser displacements compared to unreinforced slopes at all frequency levels.

Fuzzy expert system for controlling swamp terrain intelligent air-cushion tracked vehicle

A fuzzy expert system was used in this study to control an intelligent air-cushion tracked vehicle (IACTV) as it operated in a swamp peat terrain. The system was effective in controlling the intelligent air-cushion vehicle while measuring the vehicle traction (TE), motion resistance (MR), power consumption (PC), cushion clearance height (CCH) and cushion pressure (CP). An ultrasonic displacement sensor, pull-in solenoid electromagnetic switch, pressure-control sensor, microcontroller, and battery pH sensor were incorporated into the fuzzy expert system (FES) to experimentally determine the TE, MR, PC, CCH, and CP. In this study, we provide an illustration of how an FES might play an important role in the prediction of the power consumption of the vehicle’s intelligent air-cushion system. The mean relative error in the actual and predicted values from the FES model with respect to tractive effort, total motion resistance and total power consumption were found to be 5.58 %, 6.78 % and 10.63 %, respectively. For all parameters, the relative error in the predicted values was found to be less than the acceptable limit (10%), except for the total power consumption. Furthermore, the goodness of fit of the predicted values was found to be close to 1.0 as expected and, hence, indicates the good performance of the developed system.

Cushion pressure control system for an intelligent air-cushion track vehicle

This paper presents the control system of cushion pressure for the developed intelligent air-cushion track vehicle (IACTV) for operating on swamp terrain and wet fields. A novel auto-adjusting supporting system is designed for the vehicle’s intelligent air-cushion system. Focusing on minimizing the total power demand of the vehicle, an optimization model has been established, for examining the effects of vehicle parameters and load distribution on power consumption by controlling air-cushion pressure. Then optimum cushion pressure is determined based on the developed optimum pressure — sinkage relationship and the pressure in the cushion chamber is controlled by the Fuzzy controller by maintaining volume flow rate and continuously monitored by the pressure sensor attached with the cushion chamber. The ultrasonic displacement sensor is used to measure the sinkage of the vehicle. The output voltages of the ultrasonic displacement are used to operate the pull-in solenoid switch through the microcontroller which closes the circuit of the compressor motor. Distribution of vehicle load to the air-cushion system is controlled by Fuzzy Logic controller by maintaining the inside pressure of the cushion.

Evaluation of an ultrasonic displacement sensor

An ultrasonic displacement sensor is currently being investigated. A possible application for this sensor is acoustic/seismic landmine detection in which a noncontact vibrometer is employed to measure the normal surface velocity of soil. The ultrasonic sensor is an alternative displacement sensor to a laser Doppler vibrometer (LDV). The ultrasonic wavelength suggests that the ultrasonic sensor is capable of resolving displacements in the presence of rough surfaces. This functionality is of particular interest because scattering of optical signals by rough surfaces can prohibit accurate LDV measurements. The ultrasonic sensor will be evaluated in an array of surface roughness conditions. The performance of the ultrasonic sensor will be compared to the LDV for each of these cases. The relative advantages and limitations of the ultrasound system will be presented. The applicability of the ultrasonic sensor to acoustic mine detection will also be addressed.

Intelligent Fusion of Sensor Data for Product Quality Assessment in a Fishcutting Machine

This article presents three techniques of knowledge-based fuzzy sensor fusion, which are based on (1) Mamdani sup-prod composition, (2) degree of certainty, and (3) compatibility of data. The first method of sensor fusion uses Mamdani's sup-prod (or max-prod) composition, and it places equal weights on all the data sources, without considering their merit or importance. The second method uses the concept of degree of certainty. It assigns weights proportional to the degree of certainty of sensor data, and in addition to the fused output, it provides information about the certainty of the output. The third method of sensor fusion uses the idea of compatibility of data. It provides a fused output and additional knowledge about the degree of confidence in that output. This method is particularly effective when sensors provide conflicting information. The three techniques are implemented in an automated machine for mechanical processing of salmon, to determine the level of product quality (i.e., the quality of processed fish), and thereby evaluate the relative performance of the techniques. In this machine, process information is available from disparate sensors like CCD cameras, optical encoders, and an ultrasonic displacement sensor. Three sets of fish-cut data for a good, a bad, and a conflicting data cut are used in the illustrative example. The results indicate that the three methods are equally effective, but method 2, which is more sophisticated, has a slight advantage in performance over the other, at the expense of added complexity.

The use of ultrasonic techniques for the measurement and control of bed height in tumbling fluidized bed granulation

The development of a system for the measurement and control of bed height in tumbling fluidized bed granulation will be described. The measurement system consisted of an ultrasonic displacement sensor located above the powder bed and a CCD video camera which took pictures continuously from outside the granulation vessel. It was noticed from the comparison of the data obtained from the two sensors that the smoothed data from the ultrasonic sensor indicated the upper level of the condensed powder phase. Based on the system developed, fixed command control of the bed height was conducted through the granulation. The effects of bed height control on the physical properties of the granules were also investigated. As a result, troubles such as blocking and channeling which have often arisen in fluidized bed granulation at high moisture content could be thoroughly settled and continuous automated operation with favorable fluidization could be realized by means of the system developed.

The use of ultrasonic techniques for the measurement and control of bed height in tumbling fluidized bed granulation

The development of a system for the measurement and control of bed height in tumbling fluidized bed granulation will be described. The measurement system consisted of an ultrasonic displacement sensor located above the powder bed and a CCD video camera which took pictures continuously from outside the granulation vessel. It was noticed from the comparison of the data obtained from the two sensors that the smoothed data from the ultrasonic sensor indicated the upper level of the condensed powder phase. Based on the system developed, fixed command control of the bed height was conducted through the granulation. The effects of bed height control on the physical properties of the granules were also investigated. As a result, troubles such as blocking and channeling which have often arisen in fluidized bed granulation at high moisture content could be thoroughly settled and continuous automated operation with favorable fluidization could be realized by means of the system developed.