Sonar sensor interpretation for ectogeneous robots

We have developed four generations of sonar scanning systems to automatically interpret surrounding environment. The first two are stationary 3D air-coupled ultrasound scanning systems and the last two are packaged as sensor heads for mobile robots. Template matching analysis is applied to distinguish simple indoor objects. It is conducted by comparing the tested echo with the reference echoes. Important features are then extracted and drawn in the phase plane. The computer then analyzes them and gives the best choices of the tested echoes automatically. For cylindrical objects outside, an algorithm has been presented to distinguish trees from smooth circular poles based on analysis of backscattered sonar echoes. The echo data is acquired by a mobile robot which has a 3D air-coupled ultrasound scanning system packaged as the sensor head. Four major steps are conducted. The final Average Asymmetry-Average Squared Euclidean Distance phase plane is segmented to tell a tree from a pole by the location of the data points for the objects interested. For extended objects outside, we successfully distinguished seven objects in the campus by taking a sequence scans along each object, obtaining the corresponding backscatter vs. scan angle plots, forming deformable template matching, extracting interesting feature vectors and then categorizing them in a hyper-plane. We have also successfully taught the robot to distinguish three pairs of objects outside. Multiple scans are conducted at different distances. A two-step feature extraction is conducted based on the amplitude vs. scan angle plots. The final Slope1 vs. Slope2 phase plane not only separates the rectangular objects from the corresponding cylindrical

Моделі, алгоритми та програмне забезпечення для планування шляху для навігації мобільних роботів з уникненням перешкод на основі дерева октантів

Об'єкт дослідження: процес оптимізації та покращення точності руху та уникнення перешкод для навігації мобільних роботів. Предмет дослідження: моделі та методи виявлення перешкод та навігації з метою уникнення виявлених перешкод. Мета магістерської роботи: підвищення ефективності системи розпізнавання перешкод мобільними роботами для навігації у середовищі, використовуючи датчики для забезпечення дороги без зіткнень з об’єктами, які не знаходяться на одному рівні з лазерами. Методи дослідження. Для вирішення поставлених задач використані методи: пошуку шляхів, порогового значення, обробки хмари точок, генерації дерева октантів. Наукова новизна полягає у тому, що удосконалено методи системи планування шляху для навігації мобільних роботів на основі дерева октантів для якісного та точного шляху від початкової точки до заданої у просторі

Dynamic sonar perception

Thesis (Ph. D. in Marine Robotics)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2003.Includes bibliographical references (leaves 183-192).Reliable sonar perception is a prerequisite of marine robot feature-based navigation. The robot must be able to track, model, map, and recognize aspects of the underwater landscape without a priori knowledge. This thesis explores the tracking and mapping problems from the standpoint of observability. The first part of the thesis addresses observability in mapping and navigation. Features are often only partially observable from a single vantage point; consequently, they must be mapped from multiple vantage points. Measurement/feature correspondences may only be observable after a lag, and feature updates must occur after a delay. A framework is developed to incorporate temporally separated measurements such that the relevant quantities are observable. The second part of the thesis addresses observability in tracking. Although there may be insufficient information from a single measurement to estimate the state of a target, there may be enough information to observe correspondences. The minimum information necessary for a dynamic observer to track locally curved targets is derived, and the computational complexity is determined as a function of sonar design, robot dynamics, and sonar configuration. Experimental results demonstrating concurrent mapping and localization (CML) using this approach to early sonar perception are presented, including results from an ocean autonomous underwater vehicle (AUV) using a synthetic aperture sonar at the GOATS 2002 experiment in Italy.Richard J. Rikoski.Ph.D.in Marine Robotic

Ultrasonic accurate sensor platform

Ultrasonic sensors are popular devices to use for wheeled mobile-robot sensing requirements, to provide distance-to-object information. However limited resolution due to sensor beamwidth, incorrect ranging due to multiple reflections, and loss of echo due to specular reflections make the use of alternative sensor systems practically mandatory. This paper presents the implementation of a highperformance 2D sonar ranging system described by Heale and Kleeman in Fast Target Classification Using Sonar . The system is implemented on PIC18F448 and PIC18F548 microcontrollers interfaced with a PC through the Extended Parallel Protocol (EPP). A DC motor is used to rotate a pair of Polaroid 7000 sensors 360 degrees around the vertical axis. Echoes received are digitized at a sampling rate in excess of 600KHz, are buffered then sent to the PC for processing. In this paper it is shown that despite uncontrolled chirp timing jitters in the transmitter circuitry of the transducer system, an alternative method of signal processing aside from that suggested by Kleeman is viable: tests show the ability of the system to range objects at distances from 0.30 meters up to 2.0 meters, with accuracy within three millimeters. The system is able to automatically identify planar as well as corner structures, with an allowable tilt and skew of 10 and 13 degrees respectively

Ultrasonic accurate sensor platform

Ultrasonic sensors are popular devices to use for wheeled mobile-robot sensing requirements, to provide distance-to-object information. However limited resolution due to sensor beamwidth, incorrect ranging due to multiple reflections, and loss of echo due to specular reflections make the use of alternative sensor systems practically mandatory. This paper presents the implementation of a highperformance 2D sonar ranging system described by Heale and Kleeman in Fast Target Classification Using Sonar . The system is implemented on PIC18F448 and PIC18F548 microcontrollers interfaced with a PC through the Extended Parallel Protocol (EPP). A DC motor is used to rotate a pair of Polaroid 7000 sensors 360 degrees around the vertical axis. Echoes received are digitized at a sampling rate in excess of 600KHz, are buffered then sent to the PC for processing. In this paper it is shown that despite uncontrolled chirp timing jitters in the transmitter circuitry of the transducer system, an alternative method of signal processing aside from that suggested by Kleeman is viable: tests show the ability of the system to range objects at distances from 0.30 meters up to 2.0 meters, with accuracy within three millimeters. The system is able to automatically identify planar as well as corner structures, with an allowable tilt and skew of 10 and 13 degrees respectively