Indoor 3D Reconstruction Using Camera, IMU and Ultrasonic Sensors

The recent advances in sensing and display technologies have been transforming our living environments drastically. In this paper, a new technique is introduced to accurately reconstruct indoor environments in three-dimensions using a mobile platform. The system incorporates 4 ultrasonic sensors scanner system, an HD web camera as well as an inertial measurement unit (IMU). The whole platform is mountable on mobile facilities, such as a wheelchair. The proposed mapping approach took advantage of the precision of the 3D point clouds produced by the ultrasonic sensors system despite their scarcity to help build a more definite 3D scene. Using a robust iterative algorithm, it combined the structure from motion generated 3D point clouds with the ultrasonic sensors and IMU generated 3D point clouds to derive a much more precise point cloud using the depth measurements from the ultrasonic sensors. Because of their ability to recognize features of objects in the targeted scene, the ultrasonic generated point clouds performed feature extraction on the consecutive point cloud to ensure a perfect alignment. The range measured by ultrasonic sensors contributed to the depth correction of the generated 3D images (the 3D scenes). Experiments revealed that the system generated not only dense but precise 3D maps of the environments. The results showed that the designed 3D modeling platform is able to help in assistive living environment for self-navigation, obstacle alert, and other driving assisting tasks.

Ultrasonic Sensor-Based Embedded System for Vehicular Collusion Detection and Alert

The efficacy of an automated collision detection system is contingent upon the caliber and volume of data at its disposal. In the event that the data is deficient, incongruous, or erroneous, it has the potential to generate erroneous positive or negative outcomes, thereby compromising the system’s credibility. The occurrence of false positives is observed when the system erroneously identifies genuine activity as collusion. The phenomenon of false negatives arises when the system is unable to identify instances of genuine collusion. Collusion detection systems are required to handle substantial volumes of data in real time, capable of analyzing relationships between different objects. The intricate nature of collusion can pose difficulties in devising and executing efficient systems for its detection. The present study proposes an automated anti-collision system that utilizes sensor devices to detect objects and activate an alert mechanism in the event that the vehicle approaches the object in close proximity. The study introduces a novel methodology for mitigating vehicular accidents by implementing a combined system that integrates collision detection and alert mechanisms. The proposed system comprises an ultrasonic sensor, a microprocessor, and an alarm system. The sensor transmits a signal to the microcontroller, which in turn sends a signal to the warning unit. The warning unit is designed to prevent potential accidents by emitting an audible warning signal through a buzzer. Additionally, the distance information is displayed on an LCD screen. The Proteus Design Suite is utilized for simulation purposes, while Arduino.cc is employed for implementation.

Ultrasonic method for measuring water holdup of low velocity and high-water-cut oil-water two-phase flow

Oil reservoirs with low permeability and porosity that are in the middle and late exploitation periods in China＇s onshore oil fields are mostly in the high-water-cut production stage.This stage is associated with severely non-uniform local-velocity flow profiles and dispersed-phase concentration（of oil droplets） in oil-water two-phase flow,which makes it difficult to measure water holdup in oil wells.In this study,we use an ultrasonic method based on a transmission-type sensor in oil-water two-phase flow to measure water holdup in lowvelocity and high water-cut conditions.First,we optimize the excitation frequency of the ultrasonic sensor by calculating the sensitivity of the ultrasonic field using the finite element method for multiphysics coupling.Then we calculate the change trend of sound pressure level attenuation ratio with the increase in oil holdup to verify the feasibility of the employed diameter for the ultrasonic sensor.Based on the results,we then investigate the effects of oildroplet diameter and distribution on the ultrasonic field.To further understand the measurement characteristics of the ultrasonic sensor,we perform a flow loop test on vertical upward oilwater two-phase flow and measure the responses of the optimized ultrasonic sensor.The results show that the ultrasonic sensor yields poor resolution for a dispersed oil slug in water flow（D OS/W flow）,but the resolution is favorable for dispersed oil in water flow（D O/W flow） and very fine dispersed oil in water flow（VFD O/W flow）.This research demonstrates the potential application of a pulsed-transmission ultrasonic method for measuring the fraction of individual components in oil-water two-phase flow with a low mixture velocity and high water cut.

Study on contactless ultrasonic sensor and seam tracking

The sensitivity of contactless ultrasonic sensor is improved from 3.3% to 26% through acoustic and electric matching technique in this paper.Along dual crest lines auto seam tracking is firstly realized with contactless ultrasonic sensing.The focused acoustic lens is accurately designed, and a sonic beam with 0.5 mm in diameter is achieved. By means of software and hardware technique the accuracy of seam tracking with ultrasonic sensing is 0.5 mm in lateral direction and 0.2 mm in longitudinal direction respectively.

Development of seam tracking system with ultrasonic sensor using self-tuning fuzzy control

One kind of the SAW seam tracking system with contactless ultrasonic sensor is presented in this paper. The new contactless ultrasonic sensor for seam tracking and the working principle of the seam tracking with the sensor are introduced. Based on the experiments, the optimal values of the fuzzy control parameters α and k 3 are defined by means of the off line adjusting method. Because the self tuning fuzzy control is adopted in the seam tracking system, the overshoot of the system is restrained, the steady state error is reduced, and the system's response speed is improved effectively. The results of the SAW seam tracking experiments show that this system's tracking accuracy is up to ±0.5 mm and the system can satisfy the requirements of the engineering application.

Object-tracking robot using ultrasonic sensor and servo motor

This paper proposes a method that rotation angle of servo motor and distance values of ultrasonic sensor are used for tracking an object in real-time while the robot keeps regular distance.Object detection distance widens by using ultrasonic sensors and object recognition,and movement of robot is controlled by angle of servo motor and distance of ultrasonic sensors.Not adopting the existing tracking methods:camera,laser-infrared(LRF)and many ultrasonic sensors,the proposed method proves that it is possible to track object using ultrasonic sensor and servo motor.Trajectory of robot is represented and analysed according to movement of object in limited conditions.

Development of an Accurate Low-cost Ultrasonic Localization System for Autonomous Mobile Robots in Indoor Environments

An accurate low-cost ultrasonic localization system is de- veloped for automated mobile robots in indoor environments, which is essential for automatic navigation of mobile robots with various tasks. Although ultrasenic sensors are more cost-effective than other sensors such as Laser Range Finder （LRF） and vision, but they are inaccurate and directionally ambiguons. First, the matched filter is used to measure the distance accurately. For resolving the computational complexity of the matched filter, a new matched filter algorithm with simple compution is proposed. Then, an ultrasonic localization system is proposed which consists of three ultrasonic receivers and two or mote transmitters for improving position and orientation accuracy was developed. Finally, an extended Kalman filter is designed to estimate both the static and dynamic positions and orientations. Various simu lations and experimental results show that the proposed system is effective.

Design and Implementation of an Ultrasonic Heat Meter Based on MSP430F437

Flowing with the reform of the hot water heating method in China, heat meter will enter into households in the near future. A portable ultrasonic heat meter is designed in this paper. The meter uses chip microprocessor MSP430F437 as the data process core, and uses ultrasonic flow sensor to measure flow rate of the hot water, and capture input and output temperatures of the hot water using the thermal resistance sensor Ptl000, and then household energy consumption is calculated via temperature difference between input temperature and output temperature of the hot water multiplied by volume of hot water that is calculated though flow rate integration of hot water. In order to test the performance of the proposed heat meter, experiments is carried out. Both the temperature and flow measurement results satisfy the requirements of accuracy and the heat meter is effective in the heat measurement.

Modeling of liquid film thickness around Taylor bubbles rising in vertical stagnant and co-current slug flowing liquids

The hydrodynamic study of the liquid film around Taylor bubbles in slug flow has great significance for understanding parallel flow and interaction between Taylor bubbles.The prediction models for liquid film thickness mainly focus on stagnant flow,and some of them remain inaccurate performance.However,in the industrial process,the slug flow essentially is co-current flow.Therefore,in this paper,the liquid film thickness is studied by theoretical analysis and experimental methods under two conditions of stagnant and co-current flow.Firstly,under the condition of stagnant flow,the present work is based on Batchelor's theory,and modifies Batchelor's liquid film thickness model,which effectively improves its prediction accuracy.Under the condition of co-current flow,the prediction model of average liquid film thickness in slug flow is established by force and motion analysis.Taylor bubble length is introduced into the model as an important parameter.Dynamic experiments were carried out in the pipe with an inner diameter of 20 mm.The liquid film thickness,Taylor bubble velocity and length were measured by distributed ultrasonic sensor and intrusive cross-correlation conductivity sensor.Comparing the predicted value of the model with the measured results,the relative error is controlled within 10%.

Characteristics of lateral vehicular interactions in heterogeneous traffic with weak lane discipline

Heterogeneous traffic conditions prevail in developing countries. Vehicles maintain weak lane discipline which increases lateral interactions of vehicles significantly. It is necessary to study these interactions in the form of maintained lateral gaps for modeling this traffic scenario. This paper aims at determining lateral clearances maintained by different vehicle types while moving in a heterogeneous traffic stream during overtaking. These data were collected using an instrumented vehicle which runs as a part of the stream. Variation of obtained clearance with average speed of interacting vehicles is studied and modeled. Different instrumented vehicles of various types are developed using （1） ultrasonic sensors fixed on both sides of vehicle, which provide inter-vehicular lateral distance and relative speed; and （2） GPS device with cameras, which provides vehicle type and speed of interacting vehicles. They are driven on different roads in six cities of India, to measure lateral gaps maintained with different interacting vehicles at different speeds. Relationships between lateral gaps and speed are modeled as regression lines with positive slopes and beta-distributed residuals. Nature of these graphs （i.e., slopes, intercepts, residuals） are also evaluated and compared for different interacting vehicle-type pairs. It is observed that similar vehicle pairs maintain less lateral clearance than dissimilar vehicle pairs. If a vehicle interacts with two vehicles （one on each side） simultaneously, lateral clearance is reduced and safety of the vehicles is compromised. The obtained relationships can be used for simulating lateral clearance maintaining behavior of vehicles in heterogeneous traffic.

Ultrasonic guided wave inspection with array sensors

Ultrasonic guided wave becomes one of promising tool for monitoring various types of structures such as large steel plates, vessels, and pipes in oil, chemical or nuclear industry, because guided waves have ability to travel wide range of the target structure in a single position. However, analysis of guided wave signals acquired from structure is difficult on account of low S/N ratio and its dispersive nature. To improve S/N ratio and overcome dispersion effect, focusing techniques for guided waves are needed. Thus, in this study, focusing techniques for guided waves were developed in order to improve long range inspection ability, and performance of the developed techniques was verified by experiments.

Power Consumption Prediction for an Intelligent Air-Cushion Track Vehicle： Fuzzy Expert System

This paper describes the unique structure of an intelligent air-cushion system of a hybrid electrical air-cushion track vehicle working on swamp terrain. Fuzzy expert system （FES） is used in this study to control the swamp tracked vehicle＇s intelligent air cushion system while it operates in the swamp peat. The system will be effective to control the intelligent air-cushion system with total power consumption （PC）, cushion clearance height （CCH） and cushion pressure （CP）. Ultrasonic displacement sensor, pull-in solenoid electromagnetic switch, pressure sensor, micro controller and battery pH sensor will be incorporated with the FES to investigate experimentally the PC, CCH and CP. In this study, we provide illustration how FES might play an important role in the prediction of power consumption of the vehicle＇s intelligent air-cushion system. The mean relative error of actual and predicted values from the FES model on total power consumption is found as 10.63 %, which is found to be alomst equal to the acceptable limits of 10%. The goodness of fit of the prediction values from the FES model on PC is found as 0.97.

Mobile Based IoT Solution for Helping Visual Impairment Users

Blind people have many tasks to do in their lives. However, blindness generates challenges for them to perform their tasks. Many blind persons use a traditional stick to move around and to perform their tasks. But the obstacles are not detected in traditional stick, it is ineffective for visually impaired people. The blind person has no idea what kind of objects or obstacles are in front of him/her. The blind person has no idea what size the object is or how far away he or she is from it. It is difficult for a blind person to get around. To assist people with vision impairment by making many of their daily tasks simple, comfortable, and organized, they will be able to recognize anything (an obstacle for blind people). A smart stick with mobile application can be used. One of the solutions is a mobile-based Internet of Things solution, which is a stick intended to assist visually impaired people to navigate more easily. It enables blindness and low vision people to navigate and carry out their daily tasks with ease and comfort. A technologically advanced blind stick that enables visually impaired people to move with ease. This paper proposes a system of software and hardware that helps visually impairment people to find their ways in an easy and comfortable way. The proposed system uses smart stick and mobile application to help blind and visually impaired people to identify objects (such as walls, tables, vehicles, people, etc.) in their ways, this can enable them to avoid these objects. In addition, as a result, the system will notify the user through sound from the smartphone. Finally, if he/she gets lost, he will be able to send an SMS with his/her GPS location.

Analysis method and experimental study of ice accumulation detection signal based on Lamb waves

A quantitative identification method for in-flight icing has the capability to significantly enhance the safety of aircraft operations.Ultrasonic guided waves have the unique advantage of detecting icing in a relatively large area,but quantitative identification of ice layers is a challenge.In this paper,a quantitative identification method of ice accumulation based on ultrasonic guided waves is proposed.Firstly,a simulation model for the wave dynamics of piezoelectric coupling in three dimensions is established to analyze the propagation characteristics of Lamb waves in a structure consisting of an aluminum plate and an ice layer.The wavelet transform method is utilized to extract the Time of Flight(ToF)or Time of Delay(ToD)of S_(0)/B_(1) mode waves,which serves as a characteristic parameter to precisely determine and assess the level of ice accumulation.Then,an experimental system is developed to evaluate the feasibility of Lamb waves-based icing real-time detection in the presence of spray conditions.Finally,a combination of the Hampel median filter and the moving average filter is developed to analyze ToF/ToD signals.Numerical simulation results reveal a positive correlation between geometric dimensions(length,width,thickness)of the ice layer and ToF/ToD of B1 mode waves,indicating their potential as indicators for quantifying ice accumulation.Experimental results of real-time icing detection indicate that ToF/ToD will reach greater peak values with the growth of the arbitrary-shaped ice layer until saturation to effectively predict the simulation results.This study lays a foundation for the practical application of quantitative icing detection via ultrasonic guided waves.

Design and measurement of a piezoresistive ultrasonic sensor based on MEMS

A kind of piezoresistive ultrasonic sensor based on MEMS is proposed,which is composed of a membrane and two side beams.A simplified mathematical model has been established to analyze the mechanical properties of the sensor.On the basis of the theoretical analysis,the structural size and layout location of the piezoresistors are determined by simulation analysis.The boron-implanted piezoresistors located on membrane and side beams form a Wheatstone bridge to detect acoustic signal.The membrane-beam microstructure is fabricated integrally by MEMS manufacturing technology.Finally,this paper presents the experimental characterization of the ultrasonic sensor,validating the theoretical model used and the simulated model.The sensitivity reaches -116.2 dB（0 dB reference = 1 V/μbar,31 kHz）,resonant frequency is 39.6 kHz,direction angle is 55°.

The design and test of MEMS piezoresistive ultrasonic sensor arrays

The design,fabrication and packaging of a type of MEMS piezoresistive ultrasonic transducer array are introduced.The consistency of the resonance frequency and the sensitivity of the array are tested.Moreover,we detect the directivity and the multi-target identification ability of the array.The results of the consistency of the resonance frequency and the sensitivity show that there is a gap between the practical and theoretical results.This paper analyzes this problem in detail and points out the direction of improvement.As for the directivity,the actual result is consistent with the theoretical one.The results of multiple target distinguishing tests demonstrate that the smallest resolution angle of the array is 5.72°when the distance between the sensor array and measured objects is 2 m.