Celso Massatoshi Furukawa

Sensor Fusion with Low-Grade Inertial Sensors and Odometer to Estimate Geodetic Coordinates in Environments without GPS Signal

This paper presents a sensor fusion algorithm based on a Kalman Filter to estimate geodetic coordinates and reconstruct a car test trajectory in environments where there is no GPS signal. The sensor fusion algorithm is based on low-grade strapdown inertial sensors (i.e. accelerometers and gyroscopes) and an incremental odometer, from which, velocity measurements is obtained. Since the dynamic system is non linear, an Extended Kalman Filter (EKF) is used to estimate the states (i.e. latitude, longitude and altitude) and reconstruct the test trajectory. The relevance of this work is given by the fact that, in the current literature, much has been published about the merger Inertial Sensors and GPS, however, currently no literature that addresses the form of sensor fusion proposed here is available. Another aspect that could be emphasized is that the proposed algorithm has potential to be applied in environments where GPS signals are not available, such as Pipeline Inspection Gauge (PIG) as depicted below in figure 2. The inertial navigation system developed and tested, shows that only with inertial sensors measurements, a closed tested trajectory can not be reconstructed satisfactorily, however when it uses the sensor fusion, the trajectory can be reconstructed with relative success. On preliminary experiments, it was possible reconstruct a closed trajectory of approximately 2800m, attaining a final error of 13m.

Estimation of trajectories of pipeline PIGs using inertial measurements and non linear sensor fusion

This paper presents a nonlinear sensor fusion algorithm for inertial navigation designed to reconstruct trajectories of a Pipeline Inspection Gauge. Outputs of a strapdown inertial measurement unit are combined with non inertial measurements provided by an incremental odometer and a set of cartographic landmarks. The navigation system is modeled as a nonlinear dynamic system and the extended Kalman filter is used to estimate the system state. On preliminary experiments, it was possible to reconstruct a closed test trajectory with 2,800 m of extension, attaining a final error of 1.7 m.

Characterization of Lubricating Oil Using Ultrasound

This paper presents an ultrasonic method to measure small concentrations of water in lubricating oil. It uses an ultrasonic measurement cell composed by a piezoceramic emitter (5 and 10 MHz), and a large aperture PVDF receiver that eliminates diffraction effects. The propagation velocity, attenuation coefficient and density of several samples of water-in-oil emulsion were measured. The concentrations of water of the samples were in the range of 0 to 5% in volume, and the results showed that these low concentrations can be discriminated within a resolution of 0.2% in the studied range, using the measurement of the propagation velocity.

Hardware in the loop simulation applied to semi-autonomous underwater vehicles

Unmanned Underwater Vehicles (UUVs) have many commercial, military, and scientific applications because of their potential capabilities and significant cost-performance improvements over traditional means of obtaining valuable information about the underwater environment. The development of a reliable sampling and testing platform for these vehicles requires a thorough system design and many costly at-sea trials during which systems specifications can be validated. Modeling and simulation provide a cost-effective measure to carry out preliminary component, system (hardware and software), and mission testing and verification, thereby reducing the number of potential failures in at-sea trials. An accurate simulation environment can help engineers to find hidden errors in the UUV embedded software and gain insights into the UUV operation and dynamics. This work describes the implementation of a UUVs control algorithm using MATLAB/SIMULINK, its automatic conversion to an executable code (in C++) and the verification of its performance directly into the embedded computer using simulations. It is detailed the necessary procedure to allow the conversion of the models from MATLAB to C++ code, integration of the control software with the real time operating system used on the embedded computer (VxWorks) and the developed strategy of Hardware In the Loop Simulation (HILS). The Main contribution of this work is to present a rational framework to support the final implementation of the control software on the embedded computer, starting from the model developed on an environment friendly to the control engineers, like SIMULINK.

Signal processing for corrosion assessment in pipelines with ultrasound PIG using matched filter

This work describes the development of an algorithm that uses ultrasound to evaluate the degree of corrosion in pipeline walls. The developed algorithm was implemented in a dedicated digital circuit that can be embedded in ultrasonic pigs for pipeline corrosion inspection. The algorithm is based on the mathematic model known as matched filter. It also incorporates a peak detection method for the localization of ultrasound echoes, originated from the signal reflections in the pipeline walls. One of the problems is the determination of the signal (and filter) that should be used, but using a signal design approach, a large number of possibilities could be analyzed so that only a few had to be tested in experiments. Finally, the best signals were used to inspect a sample made of a corroded pipeline section, and the results were analyzed. The detection of the first wall showed promising results when compared to the results of a tridimensional inspection of the same walls. It was possible to reconstruct the profile of the internal wall with good likelihood, even in badly corroded areas. The detection of the second wall showed some satisfactory results on low corrosion levels, but showed some problems with high corrosion levels, compromising the direct measurement of the pipeline wall thickness.

Medição de viscosidade de líquidos pelo método de múltiplas reflexões acústicas com conversão de modo

This work presents a cell to measure the dynamic viscosity of liquids using a wave mode conversion from longitudinal to shear waves and vice-versa. The method is based on the measurement of the complex reflection coefficient of shear waves at a solid-liquid interface. The reflected waves at the solid-liquid interface are measured in the longitudinal mode by a large aperture PVDF membrane to avoid errors due to the acoustic diffraction. A viscosity measurement strategy was developed based on the relative multiple reflection method that guarantees the measurement of the propagation velocity for the solid. Measurements of the viscosity of automotive oils (SAE90 and SAE140) and a kind of corn glucose were made in the range of 1 to 5MHz. The experimental results show the dependency of the dynamic viscosity with the frequency of the shear wave.