UAS See-and-Avoid using two different approaches of Fuzzy Control

This work presents two UAS See and Avoid approaches using Fuzzy Control. We compare the performance of each controller when a Cross-Entropy method is applied to optimase the parameters for one of the controllers. Each controller receive information from an image processing front-end that detect and track targets in the environment. Visual information is then used under a visual servoing approach to perform autonomous avoidance. Experimental flight trials using a small quadrotor were performed to validate and compare the behaviour of both controllers

Cross-entropy optimization for scaling factors of a fuzzy controller : a see-and-avoid approach for unmanned aerial systems

The Cross-Entropy (CE) is an efficient method for the estimation of rare-event probabilities and combinatorial optimization. This work presents a novel approach of the CE for optimization of a Soft-Computing controller. A Fuzzy controller was designed to command an unmanned aerial system (UAS) for avoiding collision task. The only sensor used to accomplish this task was a forward camera. The CE is used to reach a near-optimal controller by modifying the scaling factors of the controller inputs. The optimization was realized using the ROS-Gazebo simulation system. In order to evaluate the optimization a big amount of tests were carried out with a real quadcopter.

Vision based control for micro aerial vehicles : Application to sense and avoid

This work presents a collision avoidance approach based on omnidirectional cameras that does not require the estimation of range between two platforms to resolve a collision encounter. Our method achieves minimum separation between the two vehicles involved by maximising the view-angle given by the omnidirectional sensor. Only visual information is used to achieve avoidance under a bearing- only visual servoing approach. We provide theoretical problem formulation, as well as results from real flights using small quadrotors

Robotic explosive charging in mining and construction applications

Describes the development and testing of a robotic system for charging blast holes in underground mining. The automation system supports four main tactical functions: detection of blast holes; teleoperated arm pose control; automatic arm pose control; and human-in-the-loop visual servoing. We present the system architecture, and analyse the major components, Hole detection is crucial for automating the process, and we discuss theoretical and practical aspects in detail. The sensors used are laser range finders and cameras installed in the end effector. For automatic insertion, we consider image processing techniques to support visual servoing the tool to the hole. We also discuss issues surrounding the control of heavy-duty mining manipulators, in particular, friction, stiction, and actuator saturation.

Shared autonomy for close-quarters navigation and control of a VTOL platform

This thesis presents an approach for a vertical infrastructure inspection using a vertical take-off and landing (VTOL) unmanned aerial vehicle and shared autonomy. Inspecting vertical structure such as light and power distribution poles is a difficult task. There are challenges involved with developing such an inspection system, such as flying in close proximity to a target while maintaining a fixed stand-off distance from it. The contributions of this thesis fall into three main areas. Firstly, an approach to vehicle dynamic modeling is evaluated in simulation and experiments. Secondly, EKF-based state estimators are demonstrated, as well as estimator-free approaches such as image based visual servoing (IBVS) validated with motion capture ground truth data. Thirdly, an integrated pole inspection system comprising a VTOL platform with human-in-the-loop control, (shared autonomy) is demonstrated. These contributions are comprehensively explained through a series of published papers.

Inspection of pole-like structures using a vision-controlled VTOL UAV and shared autonomy

We present an approach for the inspection of vertical pole-like infrastructure using a vertical take-off and landing (VTOL) unmanned aerial vehicle and shared autonomy. Inspecting vertical structures, such as light and power distribution poles, is a time consuming, dangerous and expensive task with high operator workload. To address these issues, we propose a VTOL platform that can operate at close-quarters, whilst maintaining a safe stand-off distance and rejecting environmental disturbances. We adopt an Image based Visual Servoing (IBVS) technique using only two line features to stabilise the vehicle with respect to a pole. Visual, inertial and sonar data are used, making the approach suitable for indoor or GPS-denied environments. Results from simulation and outdoor flight experiments demonstrate the system is able to successfully inspect and circumnavigate a pole.

Vision-based control for mining automation

The mining industry is highly suitable for the application of robotics and automation technology since the work is both arduous and dangerous. Visual servoing is a means of integrating noncontact visual sensing with machine control to augment or replace operator based control. This article describes two of our current mining automation projects in order to demonstrate some, perhaps unusual, applications of visual servoing, and also to illustrate some very real problems with robust computer vision

Special issue on robot vision

The International Journal of Robotics Research (IJRR) has a long history of publishing the state-of-the-art in the field of robotic vision. This is the fourth special issue devoted to the topic. Previous special issues were published in 2012 (Volume 31, No. 4), 2010 (Volume 29, Nos 2–3) and 2007 (Volume 26, No. 7, jointly with the International Journal of Computer Vision). In a closely related field was the special issue on Visual Servoing published in IJRR, 2003 (Volume 22, Nos 10–11). These issues nicely summarize the highlights and progress of the past 12 years of research devoted to the use of visual perception for robotics.

Design and evaluation of decision and control strategies for autonomous vision-based see and avoid systems

This paper details the design and performance assessment of a unique collision avoidance decision and control strategy for autonomous vision-based See and Avoid systems. The general approach revolves around re-positioning a collision object in the image using image-based visual servoing, without estimating range or time to collision. The decision strategy thus involves determining where to move the collision object, to induce a safe avoidance manuever, and when to cease the avoidance behaviour. These tasks are accomplished by exploiting human navigation models, spiral motion properties, expected image feature uncertainty and the rules of the air. The result is a simple threshold based system that can be tuned and statistically evaluated by extending performance assessment techniques derived for alerting systems. Our results demonstrate how autonomous vision-only See and Avoid systems may be designed under realistic problem constraints, and then evaluated in a manner consistent to aviation expectations.

Posicionamento dinâmico utilizando controle a estrutura variável e servovisão.

Neste trabalho é apresentado o desenvolvimento de um sistema de posicionamento dinâmico para uma pequena embarcação baseado em controle a estrutura variável com realimentação por visão computacional. Foram investigadas, na literatura, diversas técnicas desenvolvidas e escolheu-se o controle a estrutura variável devido, principalmente, ao modo de acionamento dos propulsores presentes no barco utilizado para os experimentos. Somando-se a isto, foi considerada importante a robustez que a técnica de controle escolhida apresenta, pois o modelo utilizado conta com incerteza em sua dinâmica. É apresentado ainda o projeto da superfície de deslizamento para realizar o controle a estrutura variável. Como instrumento de medição optou-se por utilizar técnicas de visão computacional em imagens capturadas a partir de uma webcam. A escolha por este tipo de sistema deve-se a alta precisão das medições aliada ao seu baixo custo. São apresentadas simulações e experimentos com controle a estrutura variável em tempo discreto utilizando a integral do erro da posição visando eliminar o erro em regime. Para realizar o controle que demanda o estado completo, são comparados quatro estimadores de estado realizados em tempo discreto: derivador aproximado; observador assintótico com uma frequência de amostragem igual a da câmera; observador assintótico com uma frequência de amostragem maior que a da câmera; e filtro de Kalman.

基于视觉伺服的水下机器人悬停定位

为实现水下机器人的悬停定位,提出一种基于视觉伺服的方法．通过安装在机器人上的摄像机实时摄取特定观察目标的图像,应用基于单目视觉位姿估计方法获取观察目标相对干摄像机的位姿信息,并以此作为反馈构成机器人运动的伺服控制．以本单位的水下机器人控制系统实验研究平台为载体,在实验水池内完成了实验．实验结果表明,在存在外力扰动的情况下机器人可以运动到指定位姿并保持悬停．

基于视觉伺服的输电线巡检机器人抓线控制

巡检机器人在越障时,需要完成机器人手臂的准确抓线控制.结合输电线的几何特征和摄像机成像原理,提出了一种基于单摄像机的立体视觉方法来确定输电线的位置和姿态.基于该定位方法及视觉伺服理论,建立机械手抓线伺服控制模型.利用自行研制的巡检机器人进行了视觉伺服抓线实验;实验结果验证了该方法的有效性.

输电线路巡检机器人越障控制研究

介绍了超高压输电线路巡检机器人越障控制方法。根据巡检作业任务的要求,采用遥控与局部自主控制相结合的方法,实现了巡检机器人沿线行走及跨越障碍的功能。采用基于单目摄像头定位和视觉伺服的方法,实现了巡检机器人的自主越障控制。实验结果表明,该机器人可沿线行走并自主跨越障碍,从而验证了控制系统设计的有效性与合理性。

视觉伺服分类及其动态过程

对视觉伺服进行了综述性的介绍,系统地介绍了机器人视觉伺服控制的发展历史以及现状·从控制模型给出了视觉伺服控制系统的分类·针对两种最基本的分类方式基于位置的视觉伺服和基于图像的视觉伺服进行了重点介绍·对于视觉系统和图像特征的选取问题进行了讨论,此外还对视觉伺服系统的动态过程进行了分析,指出视觉系统的延时是目前伺服控制的研究所面临的最大问题·对未来视觉伺服研究的方向进行了总结·

模型无关的无定标视觉伺服控制

本文首先介绍了视觉伺服的一般原理 .然后提出了一种模型无关的无定标视觉伺服控制方法 ,在这种方法中不需要机器人模型和摄像机模型 ,应用方差最小化的原理推导出了模型无关的无定标视觉伺服控制律 .此外还给出了图像雅可比矩阵的递推公式 .文章最后通过一个轨线跟踪的仿真实验验证了算法的正确性和有效性