206 research outputs found
Adaptive neuro-fuzzy technique for autonomous ground vehicle navigation
This article proposes an adaptive neuro-fuzzy inference system (ANFIS) for solving navigation problems of an autonomous ground vehicle (AGV). The system consists of four ANFIS controllers; two of which are used for regulating both the left and right angular velocities of the AGV in order to reach the target position; and other two ANFIS controllers are used for optimal heading adjustment in order to avoid obstacles. The two velocity controllers receive three sensor inputs: front distance (FD); right distance (RD) and left distance (LD) for the low-level motion control. Two heading controllers deploy the angle difference (AD) between the heading of AGV and the angle to the target to choose the optimal direction. The simulation experiments have been carried out under two different scenarios to investigate the feasibility of the proposed ANFIS technique. The simulation results have been presented using MATLAB software package; showing that ANFIS is capable of performing the navigation and path planning task safely and efficiently in a workspace populated with static obstacles
Navigation and Control of Automated Guided Vehicle using Fuzzy Inference System and Neural Network Technique
Automatic motion planning and navigation is the primary task of an Automated Guided Vehicle (AGV) or mobile robot. All such navigation systems consist of a data collection system, a decision making system and a hardware control system. Artificial Intelligence based decision making systems have become increasingly more successful as they are capable of handling large complex calculations and have a good performance under unpredictable and imprecise environments.
This research focuses on developing Fuzzy Logic and Neural Network based implementations for the navigation of an AGV by using heading angle and obstacle distances as inputs to generate the velocity and steering angle as output. The Gaussian, Triangular and Trapezoidal membership functions for the Fuzzy Inference System and the Feed forward back propagation were developed, modelled and simulated on MATLAB. The reserach presents an evaluation of the four different decision making systems and a study has been conducted to compare their performances.
The hardware control for an AGV should be robust and precise. For practical implementation a prototype, that functions via DC servo motors and a gear systems, was constructed and installed on a commercial vehicle
Non-linear Control of an Autonomous Ground Vehicle
In this paper, in order to select a speed controller for a specific non-linear autonomous ground vehicle, proportional-integral-derivative (PID), Fuzzy, and linear quadratic regulator (LQR) controllers were designed. Here, in order to carry out the tuning of the above controllers, a multicomputer genetic algorithm (MGA) was designed. Then, the results of the MGA were used to parameterize the PID, Fuzzy and LQR controllers and to test them under laboratory conditions. Finally, a comparative analysis of the performance of the three controllers was conducted
Autonomous navigation of a wheeled mobile robot in farm settings
This research is mainly about autonomously navigation of an agricultural wheeled mobile robot in an unstructured outdoor setting. This project has four distinct phases defined as: (i) Navigation and control of a wheeled mobile robot for a point-to-point motion. (ii) Navigation and control of a wheeled mobile robot in following a given path (path following problem). (iii) Navigation and control of a mobile robot, keeping a constant proximity distance with the given paths or plant rows (proximity-following). (iv) Navigation of the mobile robot in rut following in farm fields. A rut is a long deep track formed by the repeated passage of wheeled vehicles in soft terrains such as mud, sand, and snow.
To develop reliable navigation approaches to fulfill each part of this project, three main steps are accomplished: literature review, modeling and computer simulation of wheeled mobile robots, and actual experimental tests in outdoor settings. First, point-to-point motion planning of a mobile robot is studied; a fuzzy-logic based (FLB) approach is proposed for real-time autonomous path planning of the robot in unstructured environment. Simulation and experimental evaluations shows that FLB approach is able to cope with different dynamic and unforeseen situations by tuning a safety margin. Comparison of FLB results with vector field histogram (VFH) and preference-based fuzzy (PBF) approaches, reveals that FLB approach produces shorter and smoother paths toward the goal in almost all of the test cases examined. Then, a novel human-inspired method (HIM) is introduced. HIM is inspired by human behavior in navigation from one point to a specified goal point. A human-like reasoning ability about the situations to reach a predefined goal point while avoiding any static, moving and unforeseen obstacles are given to the robot by HIM. Comparison of HIM results with FLB suggests that HIM is more efficient and effective than FLB.
Afterward, navigation strategies are built up for path following, rut following, and proximity-following control of a wheeled mobile robot in outdoor (farm) settings and off-road terrains. The proposed system is composed of different modules which are: sensor data analysis, obstacle detection, obstacle avoidance, goal seeking, and path tracking. The capabilities of the proposed navigation strategies are evaluated in variety of field experiments; the results show that the proposed approach is able to detect and follow rows of bushes robustly. This action is used for spraying plant rows in farm field.
Finally, obstacle detection and obstacle avoidance modules are developed in navigation system. These modules enables the robot to detect holes or ground depressions (negative obstacles), that are inherent parts of farm settings, and also over ground level obstacles (positive obstacles) in real-time at a safe distance from the robot. Experimental tests are carried out on two mobile robots (PowerBot and Grizzly) in outdoor and real farm fields. Grizzly utilizes a 3D-laser range-finder to detect objects and perceive the environment, and a RTK-DGPS unit for localization. PowerBot uses sonar sensors and a laser range-finder for obstacle detection. The experiments demonstrate the capability of the proposed technique in successfully detecting and avoiding different types of obstacles both positive and negative in variety of scenarios
A Novel Path Prediction Strategy for Tracking Intelligent Travelers
There are various technologies for positioning and tracking of intelligent travelers such
as wireless local area networks (WLAN). However, the loss of actual positioning data is
a common problem due to unexpected disconnection between tracking references and
the traveler. Disconnection of the mobile terminal (MT) from the access points (AP) in
WLAN-based systems is the example case of the problem. While enhancement of the
physical system itself can reduce the risk of disconnections, complementary algorithms
provide even more robustness in localization and tracking of the traveler.
This research aims to develop a novel path prediction system which could keep track of
the traveler during temporary shortage of actual positioning data. The system takes the
advantage of the past trajectory information to compensate for the missing information
during disconnections. A novel decision support system (DSS) is devised with the
ability of learning decisional as well as kinematical behaviors of intelligent travelers. The system is then used in path prediction mode for reconstructing the missing parts of
the trajectory when actual positioning data is unavailable.
An ActivMedia Pioneer robot navigating under fuzzy artificial potential fields (APF)
and blind-folded human subjects are the two types of intelligent travelers. The reactive
motion of robots and path planning strategies of the blinds are similar in that both of
them locally acquire knowledge and explore the space based on route-like spatial
cognition. It is proposed and shown that route-like intelligent motion is based on a
combination of decisional and kinematical factors. The system is designed in such a way
to integrate these two types of motion factors using causal inference mechanism of the
fuzzy cognitive map (FCM). The FCM nodes are a novel selection of kinematical
factors. Genetic algorithm (GA) is then used to train the FCM to be able to replicate the
decisional behaviors of the intelligent traveler.
Experimental works show the capabilities of the developed DSS in human path
prediction using both simulated and actual WLAN-based positioning dataset. Locational
error is set to be limited to 1 m which is suitable for wireless tracking of human subjects
with up to 10% improvement compared to the most related works. Both simulation and
actual experiments were also carried out on the Pioneer platform. The accuracy in
prediction of robot trajectory was obtained about 83% with considerable improvement
compared to the recent methods. Apart from the positioning algorithm of this
dissertation, there are several applications of this DSS to other areas including assistive
technology for the blind and human-robot interaction
Fuzzy Controllers
Trying to meet the requirements in the field, present book treats different fuzzy control architectures both in terms of the theoretical design and in terms of comparative validation studies in various applications, numerically simulated or experimentally developed. Through the subject matter and through the inter and multidisciplinary content, this book is addressed mainly to the researchers, doctoral students and students interested in developing new applications of intelligent control, but also to the people who want to become familiar with the control concepts based on fuzzy techniques. Bibliographic resources used to perform the work includes books and articles of present interest in the field, published in prestigious journals and publishing houses, and websites dedicated to various applications of fuzzy control. Its structure and the presented studies include the book in the category of those who make a direct connection between theoretical developments and practical applications, thereby constituting a real support for the specialists in artificial intelligence, modelling and control fields
A fuzzy-logic controller for an autonomous vehicle operation in an unknown environment
A controller is developed to guide a four-wheeled vehicle through an unknown environment. The vehicle is equipped with an ultrasonic sensor that can rotate to survey the neighboring environment. A new path planning algorithm is developed that reduces the computational time while avoiding obstacles. The vehicle uses a fuzzy-logic controller to determine the corresponding change in steering. While fuzzy-logic controllers exhibit robustness under varying operating conditions, it is difficult to design a good controller when observations about the system are scarce or when the system has large number of inputs and outputs. Due to this fact, the performance of the fuzzy-logic controller is improved using nonlinear programming techniques. The algorithm automatically generates the fuzzy rules and redefines the shape of the membership sets of input and output variables for an optimal performance of the controller. The effects of changing: the velocity of the vehicle, the range of the ultrasonic sensor, and the time step of the controller of the autonomous vehicle are discussed
Using a mobile robot for hazardous substances detection in a factory environment
Dupla diplomação com a UTFPR - Universidade Tecnológica Federal do ParanáIndustries that work with toxic materials need extensive security protocols to avoid accidents.
Instead of having fixed sensors, the concept of assembling the sensors on a mobile
robot that performs the scanning through a defined path is cheaper, configurable and
adaptable. This work describes a mobile robot, equipped with several gas sensors and
LIDAR, that follows a trajectory based on waypoints, simulating a working Autonomous
Guided Vehicle (AGV). At the same time, the robot keeps measuring for toxic gases. In
other words, the robot follows the trajectory while the gas concentration is under a defined
value. Otherwise, it starts the autonomous leakage search based on a search algorithm
that allows to find the leakage position avoiding obstacles in real time. The proposed
methodology is verified in simulation based on a model of the real robot. Therefore, three
path plannings were developed and their performance compared. A Light Detection And
Ranging (LIDAR) device was integrated with the path planning to propose an obstacle
avoidance system with a dilation technique to enlarge the obstacles, thus, considering the
robot’s dimensions. Moreover, if needed, the robot can be remotely operated with visual
feedback. In addition, a controller was made for the robot. Gas sensors were embedded in
the robot with Finite Impulse Response (FIR) filter to process the data. A low cost AGV
was developed to compete in Festival Nacional de Robótica (Portuguese Robotics Open)
2019 - Gondomar, describing the robot’s control and software solution to the competition.As indústrias que trabalham com materiais tóxicos necessitam de extensos protocolos
de segurança para evitar acidentes. Ao invés de ter sensores estáticos, o conceito de
instalar sensores em um robô móvel que inspeciona através de um caminho definido é mais
barato, configurável e adaptável. O presente trabalho descreve um robô móvel, equipado
com vários sensores de gás e LIDAR, que percorre uma trajetória baseada em pontos
de controle, simulando um AGV em trabalho. Em simultâneo são efetuadas medidas de
gases tóxicos. Em outras palavras, o robô segue uma trajetória enquanto a concentração
de gás está abaixo de um valor definido. Caso contrário, inicia uma busca autônoma
de vazamento de gás com um algoritmo de busca que permite achar a posição do gás
evitando os obstáculos em tempo real. A metodologia proposta é verificada em simulação.
Três algoritmos de planejamento de caminho foram desenvolvidos e suas performances
comparadas. Um LIDAR foi integrado com o planejamento de caminho para propôr
um sistema de evitar obstáculos. Além disso, o robô pode ser operado remotamente com
auxílio visual. Foi feito um controlador para o robô. Sensores de gás foram embarcados no
robô com um filtro de resposta ao impulso finita para processar as informações. Um veículo
guiado automático de baixo custo foi desenvolvido para competir no Festival Nacional de
Robótica 2019 - Gondomar. O controle do veículo foi descrito com o programa de solução
para a competição
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