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Self-assembly of a swarm of autonomous boats into floating structures
- in Robotics and Automation (ICRA), 2014 IEEE International Conference on
, 2014
"... Abstract — This paper addresses the self-assembly of a large team of autonomous boats into floating platforms. We describe the design of individual boats, the systems concept, the al-gorithms, the software architecture and experimental results with prototypes that are 1:12 scale realizations of modi ..."
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Abstract — This paper addresses the self-assembly of a large team of autonomous boats into floating platforms. We describe the design of individual boats, the systems concept, the al-gorithms, the software architecture and experimental results with prototypes that are 1:12 scale realizations of modified ISO shipping containers, with the goal of demonstrating self-assembly into large maritime structures such as air strips, bridges, harbors or sea bases. Each container is a robotic module capable of holonomic motion that can dock in a brick pattern to form arbitrary shapes. Over 60 modules were built of varying capability. The docking mechanism is designed to be robust to large disturbances that can be expected in the high seas. The docking mechanism also incorporates adjustable stiffness so that the conglomerate can comply to waves representative of sea state three, and have the ability to dynamically stiffen as required. The component modules for autonomous assembly, docking and simultaneous collision-free planning as well as the software architecture are presented along with the description of experimental verification. I.
Electromechanical Development of a Low Cost End Effector Pose Estimation System for Articulated Excavators
"... Vision-based pose estimation, in which optical cameras monitor fiducial markers to determine the three dimensional positioning and orientation of an articulated machine’s end effector, offers a promising low-cost alternative to currently available sensor packages that are non-ubiquitous and cost pro ..."
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Vision-based pose estimation, in which optical cameras monitor fiducial markers to determine the three dimensional positioning and orientation of an articulated machine’s end effector, offers a promising low-cost alternative to currently available sensor packages that are non-ubiquitous and cost prohibitive for a large portion of the market. Whereas traditional sensor systems determine end effector pose via kine-matic chains passing through the links of a machine, optical sensor systems are capable of determining pose by observing an end effector directly. However, since markers cannot be mounted on an excavator’s bucket for occlusion and durability reasons, a short kinematic chain must be used. An electromechanical design is proposed to provide such function for a low cost marker-based excavator pose estimation system. Several iterations of design and experimentation are discussed, including a four-bar linkage system, a syn-chronous belt system, a bucket linkage system, and a cable potentiometer system. The four-bar linkage and toothed belt systems were designed to transmit bucket angle information to cameras through the manipula-tion of a marker’s pose, but were found to possess Gimbal lock and practicality issues, respectively. To overcome such issues, a generalized mapping ap-proach was adopted and implemented in a bucket linkage design and a cable potentiometer design. The viability of the cable potentiometer system was exper-imentally confirmed, along with the identification of further work needed to refine the technology for large-scale practical implementation.
i Dedication
, 2012
"... I would like to thank my adviser, Prof. Zhi-Li Zhang, for his continuous support through-out my time at school. ..."
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I would like to thank my adviser, Prof. Zhi-Li Zhang, for his continuous support through-out my time at school.
1Automated Self-Assembly of Large Maritime Structures by a Team of Robotic Boats
"... Abstract—We present the methodology, algorithms, system design, and experiments addressing the self-assembly of large teams of autonomous robotic boats into floating platforms. Identical self-propelled robotic boats autonomously dock to-gether and form connected structures with controllable variable ..."
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Abstract—We present the methodology, algorithms, system design, and experiments addressing the self-assembly of large teams of autonomous robotic boats into floating platforms. Identical self-propelled robotic boats autonomously dock to-gether and form connected structures with controllable variable stiffness. These structures can self-reconfigure into arbitrary shapes limited only by the number of rectangular elements assembled in brick-like patterns. An O(m2) complexity algorithm automatically generates assembly plans which maximize opportu-nities for parallelism while constructing operator-specified target configurations with m components. The system further features an O(n3) complexity algorithm for the concurrent assignment and planning of trajectories from n free robots to the growing structure. Such peer-to-peer assembly among modular robots compares favorably to a single active element assembling passive
FEASIBILITY OF IN-PLANE ARTICULATION MONITORING OF EXCAVATOR ARM USING PLANAR MARKER TRACKING
, 2014
"... SUMMARY: Achieving accurate excavation profiles is a challenging task for excavator operators who typically use the directions of a grade-person to achieve design grades and levels. Allocation of an extra person is costly and requires constant communication between an operator and the grade-person, ..."
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SUMMARY: Achieving accurate excavation profiles is a challenging task for excavator operators who typically use the directions of a grade-person to achieve design grades and levels. Allocation of an extra person is costly and requires constant communication between an operator and the grade-person, which reduces productivity. As a result, several machine control technology providers have developed angle sensor packages to monitor the pose of the excavator components in real-time. These systems, however, are expensive and their installation and calibration are costly and time consuming. This paper presents a generic and scalable computer-vision based framework for real-time pose estimation of an excavator’s boom and dipper (stick) using low-cost markers installed on the side of the arms. The hardware components of this system are inexpensive and the setup process is quick and straightforward. The system demonstrated promising performance and has been shown to measure boom and dipper angles with an average uncertainty of less than 0.75 ° in real-time.
Towards Autonomous Robotic In-Situ Assembly on Unstructured Construction Sites Using Monocular Vision
"... Abstract-Unlike robotics in the manufacturing industry, on-site construction robotics has to consider and address two unique challenges: 1) the rugged, evolving, and unstructured environment of typical work sites; 2) the reversed spatial relationship between the product and the manipulator, i.e. the ..."
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Abstract-Unlike robotics in the manufacturing industry, on-site construction robotics has to consider and address two unique challenges: 1) the rugged, evolving, and unstructured environment of typical work sites; 2) the reversed spatial relationship between the product and the manipulator, i.e. the manipulator has to travel to and localize itself at the work face, rather than a partially complete product arriving at an anchored manipulator. The presented research designed and implemented algorithms that address these challenges and enable autonomous robotic assembly of freeform modular structures on construction sites. Building on the authors ’ previous work in computer-vision-based pose estimation, the designed algorithms enable a mobile robotic manipulator to: 1) autonomously identify and grasp prismatic building components (e.g., bricks, blocks) that are typically non-unique and arbitrarily stored on-site; and 2) assemble these components into pre-designed modular structures. The algorithms use a single camera and a visual marker-based metrology to rapidly establish local reference frames and to detect staged building components. Based on the design of the structure being assembled, the algorithms automatically determine the assembly sequence. Implemented using a 7-axis KUKA KR100 robotic manipulator, the presented robotic system has successfully assembled various structures autonomously as shown in Figure 1, demonstrating the designed algorithms ’ effectiveness in autonomous on-site construction robotics applications.
HUMAN-ROBOT INTEGRATION FOR POSE ESTIMATION AND SEMI-AUTONOMOUS NAVIGATION ON UNSTRUCTURED CONSTRUCTION SITES
"... Compared to widespread successful deployment of robotic manipulators for repetitive and hazardous tasks in related industries such as manufacturing, the construction industry has achieved relatively limited benefits from robotics and soft automation. Unlike manufacturing, where robotic solutions ben ..."
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Compared to widespread successful deployment of robotic manipulators for repetitive and hazardous tasks in related industries such as manufacturing, the construction industry has achieved relatively limited benefits from robotics and soft automation. Unlike manufacturing, where robotic solutions benefit from the structured layout of the environment (e.g., factory assembly line), construction robots face unique challenges that arise from the rugged, dynamic, and unstructured environment of the work site, as well as the uncertainty and evolving sequence of occurring on-site events. This challenges any intended construction robots to not only replicate basic human motion, but also be capable of sensing and adapting to environmental changes, and making decisions based on the evolving state of the environment. Building upon recent advancements in robotic mapping, computer vision, and object recognition, the authors propose to introduce autonomous behavior at the basic task level for on-site construction robots to address these challenges in a flexible and extensible manner. This paper reports the outcome of the first phase of this research- a structured methodology for improved design and development of basic task automations- and focuses on algorithms developed for mobile robot navigation and relative pose estimation. The algorithms are implemented on a prototype mobile robotic platform, and evaluated in several experimental scenarios.
