Autonomous Mobile Systems Research Articles

Autonomous Power Distribution System

This paper describes path planning and control of an autonomous power distribution system. The aim is to study the use of the autonomous mobile power-grid systems after disasters to accelerate search, rescue, and recovery efforts. The concept is demonstrated through an autonomous electrical cabling and connection mission between a power source and a power load in a cluttered environment using lab-size platforms. The developed system will be scalable to real-size. The ultimate goal of this work is developing intelligent power electronics and a distributed autonomous mobile microgrid. It will be capable of regulating power flow at a desired voltage and frequency level, meeting load demands and adaptable to changes in situation, power demands, or generations.

709 放射線量測定のための自律移動システムの開発(GS-15 ロボティクス(3))

709 放射線量測定のための自律移動システムの開発(GS-15 ロボティクス(3))

Safety and Precision of Spatial Context Models for Autonomous Systems

A safe (i.e. collision-free) and efficient movement of a mobile autonomous system requires a correct assessment of the vehiclesʼ environment. In many systems, the spatial context is represented by means of an occupancy grid, that is, a partitioning of a two-dimensional area into finitely many cells where each cell maintains a probabilistic estimation of being occupied by some object. Often, this representation is complemented by dedicated information regarding the detected objects. We instantiate a generic framework based on a formal notion of abstraction for characterising the safety and precision of such kind of spatial context models. In this approach, the sensory perception corresponds to an abstraction function, and the concretisation function reflects the loss of information with respect to the real environment. We show that this method is able to derive both qualitative and quantitative measures for different variants of spatial context models.

Distributed Diagnosis of a Networked Mini-UAV

This paper describes a model-based approach for the fault detection of a mini-UAV over a wireless network. Wireless networks are preferred for the control and diagnosis of mobile autonomous systems due to their flexible architecture and roaming advantage. The major goal of this research is the development and implementation of a network strategy for real time distributed diagnosis of the flight control system of a mini-UAV. The system under investigation consists of an embedded controller area network for the onboard control and one part of diagnosis strategy. Another part of diagnosis is achieved through a low power ZigBee wireless network. This work consists of defining and evaluating the wireless loop-based diagnosis, reconfiguration and its consequences on the performance of the mini-UAV.

A Flow-based Motion Perception Technique for an Autonomous Robot System

Visual motion perception from a moving observer is the most often encountered case in real life situations. It is a complex and challenging problem, although, it can promote the arising of new applications. This article presents an innovative and autonomous robotic system designed for active surveillance and a dense optical flow technique. Several optical flow techniques have been proposed for motion perception however, most of them are too computationally demanding for autonomous mobile systems. The proposed HybridTree method is able to identify the intrinsic nature of the motion by performing two consecutive operations: expectation and sensing. Descriptive properties of the image are retrieved using a tree-based scheme and during the expectation phase. In the sensing operation, the properties of image regions are used by a hybrid and hierarchical optical flow structure to estimate the flow field. The experiments prove that the proposed method extracts reliable visual motion information in a short period of time and is more suitable for applications that do not have specialized computer devices. Therefore, the HybridTree differs from other techniques since it introduces a new perspective for the motion perception computation: high level information about the image sequence is integrated into the estimation of the optical flow. In addition, it meets most of the robotic or surveillance demands and the resulting flow field is less computationally demanding comparatively to other state-of-the-art methods.

Nested Graph Representation for Visual SLAM based on Local and Global Feature Processing

Self localization of mobile autonomous systems is fundamental step in various applications, such as assistant navigation systems for blind people or smart house appliances. This paper presents a novel framework for Vision-based Simultaneous Localization and Mapping which focuses on the class of indoor mobile robots using only a monocular camera. A method to combine local and global features mapping have been proposed in a nested graph representation, where the indoor environment is divided into locations which is then decomposed into dierent views. The Scale Invariant Feature Transform is used to extract and build up a global map which provide rough estimation of the robot position. Horizontal, vertical and diagonal details of the wavelet coecients are then used to provide finer estimation of the robot position and pose. The output topological map is validated with the ground truth of the environment. Moreover, the number of decomposition levels of the wavelet transform is analysed. The results show high localization accuracy and low rate of matching time.

Optical 3D laser measurement system for navigation of autonomous mobile robot

In our current research, we are developing a practical autonomous mobile robot navigation system which is capable of performing obstacle avoiding task on an unknown environment. Therefore, in this paper, we propose a robot navigation system which works using a high accuracy localization scheme by dynamic triangulation. Our two main ideas are (1) integration of two principal systems, 3D laser scanning technical vision system (TVS) and mobile robot (MR) navigation system. (2) Novel MR navigation scheme, which allows benefiting from all advantages of precise triangulation localization of the obstacles, mostly over known camera oriented vision systems. For practical use, mobile robots are required to continue their tasks with safety and high accuracy on temporary occlusion condition. Presented in this work, prototype II of TVS is significantly improved over prototype I of our previous publications in the aspects of laser rays alignment, parasitic torque decrease and friction reduction of moving parts. The kinematic model of the MR used in this work is designed considering the optimal data acquisition from the TVS with the main goal of obtaining in real time, the necessary values for the kinematic model of the MR immediately during the calculation of obstacles based on the TVS data.

Mobile Autonomous Router System for Dynamic (Re)formation of Wireless Relay Networks

Multihop wireless relays can extend the area of network connectivity instantly and efficiently. However, due to the spatial dependence of wireless link-quality, the deployment of relay nodes requires extensive, expensive measurement, and management efforts. This paper presents a mobile autonomous router system, (MARS) through which a relay router autonomously seeks and adjusts the best receptiona position for itself and cooperatively forms a string-type relay network with other neighboring routers. Specifically, MARS 1) accurately characterizes spatial link-quality through a new measurement technique, 2) effectively probes/optimizes node positioning via a spatial probing algorithm, and 3) maintains error-tolerant position information via an inexpensive positioning algorithm. MARS has been prototyped with both a commodity mobile robot and a wireless router with IEEE 802.11 cards. Our experimental evaluation of both the MARS prototype and ns-2-based simulation show that MARS achieves an average of 95 percent accuracy in link-quality measurements, and reduces the measurement effort necessary for the optimization of a node's location by two-thirds, compared to exhaustive spatial probing.

Optimal routing strategies for autonomous underwater vehicles in time-varying environment

This paper presents a mission system and the therein implemented algorithms for path planning in a time-varying environment based on graph methods. The basic task of the introduced path planning algorithms is to find a time-optimal path from a defined start position to a goal position with consideration of the time-varying ocean current for an autonomous underwater vehicle (AUV). Building on this, additional practice-oriented considerations in planning are discussed in this paper. Such points are the discussion of possible methods to accelerate the algorithms and the determination of the optimal departure time. The solutions and algorithms presented in this paper are focused on path planning requirements for the AUV “SLOCUM Glider”. These algorithms are equally applicable to other AUVs or aerial mobile autonomous systems.

An Autonomous Mobile System for the Management of COPD

An Autonomous Mobile System for the Management of COPD

An autonomous mobile system for the management of COPD

Managing chronic disease through automated systems has the potential to both benefit the patient and reduce health-care costs. We have developed and evaluated a disease management system for patients with chronic obstructive pulmonary disease (COPD). Its aim is to predict and detect exacerbations and, through this, help patients self-manage their disease to prevent hospitalisation. The carefully crafted intelligent system consists of a mobile device that is able to collect case-specific, subjective and objective, physiological data, and to alert the patient by a patient-specific interpretation of the data by means of probabilistic reasoning. Collected data are also sent to a central server for inspection by health-care professionals. We evaluated the probabilistic model using cross-validation and ROC analyses on data from an earlier study and by an independent data set. Furthermore a pilot with actual COPD patients has been conducted to test technical feasibility and to obtain user feedback. Model evaluation results show that we can reliably detect exacerbations. Pilot study results suggest that an intervention based on this system could be successful.

A new methodology for non-contact accurate crack width measurement through photogrammetry for automated structural safety evaluation

In mechanical, aerospace and civil structures, cracks are important defects that can cause catastrophes if neglected. Visual inspection is currently the predominant method for crack assessment. This approach is tedious, labor-intensive, subjective and highly qualitative. An inexpensive alternative to current monitoring methods is to use a robotic system that could perform autonomous crack detection and quantification. To reach this goal, several image-based crack detection approaches have been developed; however, the crack thickness quantification, which is an essential element for a reliable structural condition assessment, has not been sufficiently investigated. In this paper, a new contact-less crack quantification methodology, based on computer vision and image processing concepts, is introduced and evaluated against a crack quantification approach which was previously developed by the authors. The proposed approach in this study utilizes depth perception to quantify crack thickness and, as opposed to most previous studies, needs no scale attachment to the region under inspection, which makes this approach ideal for incorporation with autonomous or semi-autonomous mobile inspection systems. Validation tests are performed to evaluate the performance of the proposed approach, and the results show that the new proposed approach outperforms the previously developed one.

Design and Implementation of Geometric Descriptions Based on XML

Object recognition and reconstruction plays an important role in the area of 3D robot vision, which has wide applications in autonomous mobile system. For communication between heterogeneous applications, generalized and universal object description file format is needed to be developed to replace proprietary file format. In this paper, first, a new object description model was designed by using XML Schema definition language. Second, based on the description design, a dynamic link library (dll) was implemented for converting data format among different systems. At the end, experimental results are demonstrated.

Hierarchical finite state machines for autonomous mobile systems

This paper proposes a system architecture, related design approaches for autonomous mobile systems and guidelines for self-sufficient autonomy. Development of a tiered layout for a hybrid-state control in a series of stages as well as the integration of such a controller in the overall autonomy structure are proposed and demonstrated as part of multiple examples, including The Ohio State University participation in DARPA Urban Challenge 2007. The hierarchical layout and the iterative design methodology enable a certain level of design flexibility for the overall system and preparation for various contingencies, as illustrated on specific development cycles.

Software Design of Restaurant Service Mobile Robot’s Control System

The modular design of restaurant service autonomous mobile robot control system has been done, and the system adopted distributed control, the control system of the host (such as computer module) through the unity of the bus and protocols for coordination of each module. The control system distributed in the three modules of the power and driver module (including power management unit, motion control unit, and drive unit), the sensor module (various sensors, etc.), and control computer modules. Then, using VC++ 6.0 developed the software of the control system, and the software is divided into user-level, decision making control layer, sensing/underlying decision making, and movement execution layer. Communication between layers and layers are standard physical layer and protocol layer, so each layer has a highly scalable, the user is free to increase the user's own equipment and control procedures just in accordance with the standard physical layer and protocol specification.

1P1-I09 自律型天井クレーンシステムの開発 : オンライン障害物回避経路計画システムの開発(生産システム・生産機器メカトロニクス)

This paper presents a method for establishing a three-dimensional (3-D) autonomous mobile overhead crane system that takes into account obstacle recognition and path planning online. It is especially necessary for the online path planning occurring during transferring to be carried out relatively quickly. This paper describes a method of path planning that can be carried out in a short time with an easy algorithm. Online path planning has been achieved using information regarding obstacles around the object being manipulated as obtained by ultrasonic sensor. Finally, we have confirmed the usefulness of the proposed method by transfer experiment based on simulation.

A Novel Combined SLAM Based on RBPF-SLAM and EIF-SLAM for Mobile System Sensing in a Large Scale Environment

Mobile autonomous systems are very important for marine scientific investigation and military applications. Many algorithms have been studied to deal with the computational efficiency problem required for large scale Simultaneous Localization and Mapping (SLAM) and its related accuracy and consistency. Among these methods, submap-based SLAM is a more effective one. By combining the strength of two popular mapping algorithms, the Rao-Blackwellised particle filter (RBPF) and extended information filter (EIF), this paper presents a Combined SLAM—an efficient submap-based solution to the SLAM problem in a large scale environment. RBPF-SLAM is used to produce local maps, which are periodically fused into an EIF-SLAM algorithm. RBPF-SLAM can avoid linearization of the robot model during operating and provide a robust data association, while EIF-SLAM can improve the whole computational speed, and avoid the tendency of RBPF-SLAM to be over-confident. In order to further improve the computational speed in a real time environment, a binary-tree-based decision-making strategy is introduced. Simulation experiments show that the proposed Combined SLAM algorithm significantly outperforms currently existing algorithms in terms of accuracy and consistency, as well as the computing efficiency. Finally, the Combined SLAM algorithm is experimentally validated in a real environment by using the Victoria Park dataset.

Autonomous mobile robot navigation system designed in dynamic environment based on transferable belief model

This paper investigates the possibility of using transferable belief model (TBM) as a promising alternative for the problem of path planning of nonholonomic mobile robot equipped with ultrasonic sensors in an unknown dynamic environment, where the workspace is cluttered with static obstacles and moving obstacles. The concept of the transferable belief model is introduced and used to design a fusion of ultrasonic sensor data. A new strategy for path planning of mobile robot is proposed based on transferable belief model. The robot’s path is controlled using proposed navigation strategy that depends on navigation parameters which is modified by TBM pignistic belief value. These parameters are tuned in real time to adjust the path of the robot. A major advantage of the proposed method is that, with detection of the robot’s trapped state by ultrasonic sensor, the navigation law can determine which obstacle is dynamic or static without any previous knowledge, and then select the relevant obstacles for corresponding robot avoidance motion. Simulation is used to illustrate collision detection and path planning.

Self-Management Framework for Mobile Autonomous Systems

The advent of mobile and ubiquitous systems has enabled the development of autonomous systems such as wireless-sensors for environmental data collection and teams of collaborating Unmanned Autonomous Vehicles (UAVs) used in missions unsuitable for humans. However, with these range of new application-domains comes a new challenge—enabling self-management in mobile autonomous systems. Autonomous systems have to be able to manage themselves individually as well as form self-managing teams which are able to adapt to failures, protect themselves from attacks and optimise performance. This paper proposes a novel distributed policy-based framework that enables autonomous systems of varying scale to perform self-management individually and as a team. The framework allows missions to be specified in terms of roles in an adaptable and reusable way, enables dynamic and secure team formation with a utility-based approach for optimal role assignment, caters for communication link maintenance amongst team-members and recovery from failure. Adaptive management is achieved by employing a policy-based architecture to enable dynamic modification of the management strategy relating to resources, role behaviour, communications and team management, without interrupting the basic software within the system. Evaluation of the framework shows that it is scalable with respect to the number of roles, and consequently the number of autonomous systems involved in the mission. It is also optimal with respect to role assignments, and robust to intermittent communication link and permanent team-member failures.

Using an autonomous robot to maintain privacy in assistive environments

ABSTRACTIn our societies, the number of senior citizens living on their own is increasing steadily. The lack of permanent attention results in the late detection of emergency situations. Labour‐intensive care is already a high burden for the society; therefore, it seems reasonable to promote technology that helps to detect and react in case of emergency situations that elderly people may encounter.In the last decade, assistive environments have been established by integrating surveillance devices into the living environments giving remote operators access to monitor the senior inhabitant at home for detecting emergency situations. However, due to poor privacy in terms of intrusion into the private life of an elderly person, there will be an unfavourably low acceptance of such systems.This paper introduces a two‐stage strategy and proposes to replace a possibly large number of human‐controlled monitoring devices by a single autonomous mobile system. The first stage will be performed by the autonomous system to detect an emergency situation. The human operator will be obligatory only at the final stage when the system assumes that an emergency has occurred and the final evaluation of the situation is required. The self‐assessment will reduce the human factor related to privacy issues. Copyright © 2011 John Wiley & Sons, Ltd.