Showing papers on "Mobile robot published in 1986"

A robust layered control system for a mobile robot

Abstract: A new architecture for controlling mobile robots is described. Layers of control system are built to let the robot operate at increasing levels of competence. Layers are made up of asynchronous modules that communicate over low-bandwidth channels. Each module is an instance of a fairly simple computational machine. Higher-level layers can subsume the roles of lower levels by suppressing their outputs. However, lower levels continue to function as higher levels are added. The result is a robust and flexible robot control system. The system has been used to control a mobile robot wandering around unconstrained laboratory areas and computer machine rooms. Eventually it is intended to control a robot that wanders the office areas of our laboratory, building maps of its surroundings using an onboard arm to perform simple tasks.

Real-time obstacle avoidance for manipulators and mobile robots

Abstract: This paper presents a unique real-time obstacle avoidance approach for manipulators and mobile robots based on the artificial potential field concept. Collision avoidance, tradi tionally considered a high level planning problem, can be effectively distributed between different levels of control, al lowing real-time robot operations in a complex environment. This method has been extended to moving obstacles by using a time-varying artificial patential field. We have applied this obstacle avoidance scheme to robot arm mechanisms and have used a new approach to the general problem of real-time manipulator control. We reformulated the manipulator con trol problem as direct control of manipulator motion in oper ational space—the space in which the task is originally described—rather than as control of the task's corresponding joint space motion obtained only after geometric and kine matic transformation. Outside the obstacles' regions of influ ence, we caused the end effector to move in a straight line with an...

Legged Robots That Balance

Abstract: This book, by a leading authority on legged locomotion, presents exciting engineering and science, along with fascinating implications for theories of human motor control. It lays fundamental groundwork in legged locomotion, one of the least developed areas of robotics, addressing the possibility of building useful legged robots that run and balance.The book describes the study of physical machines that run and balance on just one leg, including analysis, computer simulation, and laboratory experiments. Contrary to expectations, it reveals that control of such machines is not particularly difficult. It describes how the principles of locomotion discovered with one leg can be extended to systems with several legs and reports preliminary experiments with a quadruped machine that runs using these principles.Raibert's work is unique in its emphasis on dynamics and active balance, aspects of the problem that have played a minor role in most previous work. His studies focus on the central issues of balance and dynamic control, while avoiding several problems that have dominated previous research on legged machines.Marc Raibert is Associate Professor of Computer Science and Robotics at Carnegie-Mellon University and on the editorial board of The MIT Press journal, "Robotics Research. Legged Robots That Balance" is fifteenth in the Artificial Intelligence Series, edited by Patrick Winston and Michael Brady.

Multiresolution path planning for mobile robots

Abstract: The problem of automatic collision-free path planning is central to mobile robot applications. An approach to automatic path planning based on a quadtree representation is presented. Hierarchical path-searching methods are introduced, which make use of this multiresolution representation, to speed up the path planning process considerably. The applicability of this approach to mobile robot path planning is discussed.

Dynamic path planning for a mobile automaton with limited information on the environment

Abstract: The problem of path planning is studied for the case of a mobile robot moving in an environment filled with obstacles whose shape and positions are not known. Under the accepted model, the automaton knows its own and the target coordinates, and has a "sensory" feedback which provides it with local information on its immediate surroundings. Ibis information is shown to be sufficient to guarantee reaching a global objective (the target), while generating reasonable (if not optimal) paths. A lower bound on the length of paths generated by any algorithm operating with uncertainty is formulated, and two nonheuristic path planning algorithms are described. In the algorithms, motion planning is done continuously (dynamically), based on the automaton's current position and on its feedback. The effect of additional sources of information (e.g., from a vision sensor) on the outlined approach is discussed.

Recharge docking system for mobile robot

Abstract: A recharge docking system for a battery-powered mobile robot which senses when the battery charge is below a predetermined level and halts the travel of the robot at its next navigational node, following which the robot independently plots and negotiates a path from the next node back to a base node at a recharge station, where the batteries are charged.

An architecture for sensor fusion in a mobile robot

Abstract: This paper describes sensor fusion in the context of an autonomous mobile robot. The requirements of a complex mission, real-world operation, and real-time control dictate many facets of the system architecture. The hardware architecture must include both general-purpose and special-purpose computers, and multiple sensors of various modalities (vision, range, etc.). The software architecture must allow modular development of a parallel system that supports many perceptual modalities and navigation planning tasks, but at the same time enforces global consistency regarding position and orientation of the vehicle and sensors. We are building such a system at CMU, called the NAVLAB system, based on a commercial truck with computer controls and studded with cameras and other sensors. This paper describes the software architecture of the NAVLAB, consisting of two parts: a "whiteboard" system called CODGER that is similar to a blackboard but supports parallelism in the knowledge source modules, and an organized collection of perceptual and navigational modules tied together by the CODGER system. In general, the system philosophy is to provide as much top-down guidance as possible, and to exploit sensor modality differences to produce complementary rather than competing perceptual processes in the system. In this way, the limitations of each sensor modality are compensated for as much as possible by other sensors or by higher level knowledge. The NAVLAB is being produced as part of the DARPA Strategic Computing Initiative, in conjunction with the Autonomous Land Vehicle project.

Time-optimal motions of robots in assembly tasks

Abstract: For a cylindrical, and a spherical robot, and a robot with a horizontal articulated arm with two links, time-optimal unconstrained trajectories for arbitrary fixed initial and final positions are calculated. The exact equations of motion are utilized. The controls (torques and forces) are limited. The general structure of the optimal solution is discussed and explained physically for each robot. The importance of such analyses during the mechanical design of a robot is pointed out. The reduction of the duration of an optimal motion, compared to more straightforward and natural ones, and hence the increase of the productivity of the robot in an assembly cycle can be considerable. The numerical examples include the "Automelec ACR" and the "IBM 7535 B 04" robots.

A sonar-based mapping and navigation system

Abstract: This paper describes a sonar-based mapping and navigation system for autonomous mobile robots operating in unknown and unstructured surroundings. The system uses sonar range data to build a multileveled description of the robot's environment. Sonar maps are represented in the system along several dimensions: the Abstraction axis, the Geographical axis, and the Resolution axis. Various kinds of problem-solving activities can be performed and different levels of performance can be achieved by operating with these multiple representations of maps. The major modules of the Dolphin system are described and related to the various mapping representations used. Results from actual runs are presented and further research is mentioned. The system is also situated within the wider context of developing an advanced software architecture for autonomous mobile robots.

Joint torques for control of two coordinated moving robots

Abstract: Tasks for two coordinated industrial robots always bring the robots in contact with a same object. Physically the three form a closed kinematic chain mechanism. When the chain is in motion, the positions and orientations of the two robots must satisfy a set of holonomic equality constraints for every time instant. To eliminate motion errors between them, one of them is assigned to carry the major part of the task. Its motion is planned accordingly. The motion of the second robot is to follow that of the first robot as specified by the relations of the joint velocities derived from the constraint conditions. Thus if any modification of the motion is needed in real time, only the motion of the first robot is modified. The modification for the second robot is done implicitly through the constraint conditions. Specifically, when the joint displacements, velocities, accelerations and torques/forces of the first robot are known for the planned or modified motion, the corresponding variables for the second robot can be determined through the constrained relations.

Progress in robot road-following

Abstract: We report progress in visual road following by autonomous robot vehicles. We present results and work in progress in the areas of system architecture, image rectification and camera calibration, oriented edge tracking, color classification and road-region segmentation, extracting geometric structure, and the use of a map. In test runs of an outdoor robot vehicle, the Terregator, under control of the Warp computer, we have demonstrated continuous motion vision-guided road-following at speeds up to 1.08 km/hour with image processing and steering servo loop times of 3 sec.

The Potential Field Approach And Operational Space Formulation In Robot Control

Abstract: The paper presents a radically new approach to real-time dynamic control and active force control of manipulators In this approach the manipulator control problem is reformulated in terms of direct control of manipulator motion in operational space, the space in which the task is originally described, rather than controlling the task’s corresponding joint space motion obtained after geometric and kinematic transformation The control method is based on the construction of the manipulator end effector dynamic model in operational space Also, the paper presents a unique real-time obstacle avoidance method for manipulators and mobile robots based on the “artificial potential field” concept In this method, collision avoidance, traditionally considered a high level planning problem, can be effectively distributed between different levels of control, allowing real-time robot operations in a complex environment Using a time-varying artificial potential field, this technique has been extended to moving obstacles A two-level control architecture has been designed to increase the system real-time performance These methods have been implemented in the COSMOS system for a PUMA 560 robot arm We have demonstrated compliance, contact, sliding, and insertion operations using wrist and finger sensing, as well as real-time collision avoidance with moving obstacles using visual sensing

Outdoor scene analysis using range data

Abstract: This paper describes techniques for outdoor scene analysis using range data. The purpose of these techniques is to build a 3-D representation of the environment of an mobile robot equipped with a range sensor. Algorithms are presented for scene segmentation, object detection, map building, and object recognition. We present results obtained in an outdoor navigation environment in which a laser range finder is mounted on a vehicle. These results have been successfully applied to the problem of path planning through obstacles.

Dynamic omnidirectional vision for mobile robots

Abstract: Mobile robotic devices hold great promise for a variety of applications in industry. A key step in the design of a mobile robot is to determine the navigation method for mobility control. The purpose of this paper is to describe a new algorithm for omnidirectional vision navigation. A prototype omnidirectional vision system and the implementation of the navigation techniques using this modern sensor and an advanced automatic image processor is described. The significance of this work is in the development of a new and novel approach—dynamic omnidirectional vision for mobile robots and autonomous guided vehicles.

A strategy for obstacle avoidance and its application to mullti-robot systems

Abstract: We present a local method for obstacle avoidance based on the existence of extreme separating hyperplanes. Its application is then extended to the coordinated motion of several mobile robots, and to the avoidance of two manipulators. The techniques of local planning we develop here prove to be an interesting substitute to the potential field method, as they provide a simple geometric support for the analysis.

Tutorial on robotics

Abstract: Basic fundamentals in robotics are presented in this tutorial. Topics covered are as follows: robot arm kinematics; robot arm dynamics; planning or manipulator trajectories; servo control for manipulators; force sensing and control; robot vision systems; robot programming languages; and machine intelligence and robot planning.

Robotics and Artificial Intelligence

Abstract: I. Introduction and Overview.- State of the Art and Predictions for Artificial Intelligence and Robotics.- Artificial Intelligence and Robotics.- Robotics.- II. Sensors, Manipulators, and Pattern Recognition.- Methods for Choosing Actuators and Transmission Components for High Performance Manipulators.- Tactile Sensing for Robots.- Automatic Recognition of Low Resolution Tactile Sensing Data Using Rapid Transformation.- On Patterns and Pattern Recognition.- Segmentation of Digital Arcs.- III. Languages, Software and Cad.- Automatic Synthesis of Robot Programs from CAD Specifications.- Languages for Programming Robots.- CAD, Robot Programming and Ada.- New Directions in Computer-Aided Design/Computer-Aided Manufacturing (CAD/CAM) Systems.- IV. Vision, Object Representation, Shape and Solid Modeling.- Object Representation, Identification, and Positioning from Range Data.- Representing Shape.- Two Multi-Processor Systems for Low-Level Real-Time Vision.- Tracking Robot Motion in Three-Dimensional Space: A Laser Scanning Approach.- V. Systems, Control and Mobility.- Nonlinear Control with Hierarchy for Coordinated Operation of Robots.- Machines That Walk.- Mobile Robots.- Sensor Programming - A New Way for Teaching a Robot Paths and Sensory Patterns Simultaneously.- Application of Variable Structure Systems Theory in Manipulator Control.- Robotic Mechanics and Animal Morphology.- VI. Applications.- Industrial.- Applications and Requirements for Industrial Robots.- Applications of Industrial Robots.- Applications of Industrial Robots - Technical and Economical Constraints.- Robot Applications Within General Motors.- The IBM European Robotic Applications Laboratory.- The Organizational Impacts of Computer Based Manufacturing.- Recovering from Failures: A New Challenge for Industrial Robots.- Medical.- to Robotics in Medicine.- Expert Systems and the Concept of Knowledge.- Robotics at a Biomedical Cyclotron Facility.- Medical Laboratory Automation Using Robotics.- The Application of Robotics to the Patient with High Spinal Cord Injury.- VII. The future.- Industrial Robots: Present and Future.- Social Implications of Automation.- List of Speakers.- List of Participants.

Dynamic Simulation of a Leadscrew Driven Flexible Robot Arm and Controller

Abstract: High performance requirements in robotics have led to the consideration of struc­ tural flexibilty in robot arms. This paper employs an assumed modes method to model the flexible motion of the last link of a spherical coordinate robot arm. The model, which includes the non backdrivability of the leadscrews, is used to in­ vestigate relationships between the arm structural flexibility and a linear controller for the rigid body motion. This simple controller is used to simulate the controllers currently used in industrial robots. The simulation results illustrate the differences between leadscrew driven and unconstrained axes of the robot; they indicate the trade-off between speed and accuracy; and show potential instability mechanisms due to the interaction between the controller and the robot structural flexibility.

Multisensory robots and sensor-based path generation

Abstract: The paper first outlines the recent sensory developments in the DFVLR robotics lab, these are different force-torque sensors, laser range finders, inductive sensors and sensor balls for robot and 3D-computer-grafic control. With the example of our proposed multisensory arrangement implying vision, range sensing, force-torque and speech, the fine-motion planning and path generation techniques as developed in our lab are discussed. The special case of a two-arm cooperative robot using two force-torque-sensors is treated in more detail. Practical results are demonstrated in a film including cooperative two arm robot control.

Robot motion planning with uncertainty in the geometric models of the robot and environment: A formal framework for error detection and recovery

Abstract: This paper addresses robot motion planning with uncertainty in sensing, control, and the geometric models of the robot and environment. To this end, a formal framework for error detection and recovery is proposed.

Design of a robot capable of moving on a vertical wall

Abstract: The development of a mobile robot which can work on the vertical walls of tall buildings, the side walls of large ships, etc. has been expected for a long time. A magnetic force or vacuum pressure ...

Minimum-time navigation of an unmanned mobile robot in a 2-1/2D world with obstacles

Abstract: In a 2-1/D world an isolines-based world representation is employed. An algorithm of navigation is proposed based upon polygonization of the isolines, and use of the vertices of the polygon as nodes in the graph search. Quanitative recommendations are given concerning the required density of isolines and the error of polygonization. When a physical model of mechanical motion is applied, this algorithm of navigation provides minimum-time trajectories of motion. The results of navigation are illustrated using a simulation system developed for an Intelligent Mobile Autonomous System (unmanned robot).

Path Planning for a Vision-Based Autonomous Robot

Abstract: THE VISIONS RESEARCH ENVIRONMENT AT THE UNIVERSITY OF MASSACHUSETTS PRO- VIDES AN INTEGRATED SYSTEM FOR THE INTERPRETATION OF VISUAL DATA. TO PRO- VIDE A TESTBED FOR MANY OF THE ALGORITHMS DEVELOPED WITHIN THIS FRAMEWORK, A MOBILE ROBOT HAS BEEN ACQUIRED. THE TEST DOMAINS OF INTERACTIONS ARE TWOFOLD: THE INTERIOR OF A LARGE RESEARCH CENTER BUILDING (ROOMS, HALLS, FOYERS, DOORWAYS, ETC.) AND THE IMMEDIATE OUTDOOR AREA SURROUNDING THE BUILDING (SIDEWALKS, GRAVEL PATHS, GRASS PATHS, GRASS PATCHES, BUILDING ENTRANCES, ETC.). A MULTI-LEVEL REPRESENTATION AND THE ACCOMPANYING ARCHITECTURE USED TO SUPPORT MULTI-SENSOR NAVIGATION (PREDOMINANTLY VISUAL) ARE DESCRIBED. A HYBRID VERTEX-GRAPH FREE-SPACE REPRESENTATION BASED UPON THE DECOMPOSITION OF FREE SPACE INTO CONVEX REGIONS CAPABLE FOR USE IN BOTH INDOOR AND LIMIT- ED OUTDOOR NAVIGATION IS DISCUSSED. THIS "MEADOW MAP" IS PRODUCED VIA THE RECURSIVE DECOMPOSITION OF THE INITAL BOUNDING AREA OF TRAVERSABILITY AND ITS ASSOCIATED MODELLED OBSTACLES. OF PARTICULAR INTEREST IS THE CAPABIL- ITY TO HANDLE MULTIPLE TERRAIN TYPES (SIDEWALKS, GRASS, GRAVEL, ETC.). "TRANSITION ZONES" EASE THE PASSAGE OF THE ROBOT FROM ONE TERRAIN TYPE TO ANOTHER. A HIERARCHICAL PATH PLANNER, (MISSION PLANNER, NAVIGATOR, AND PILOT), THAT UTILIZES THE DATA AVAILABLE IN THE ABOVE REPRESENTATIONAL SCHEME IS

Robot navigation in an unexplored terrain

Abstract: Navigation planning is one of the most vital aspects of an autonomous mobile robot. Robot navigation for completely known terrain has been solved in many cases. Comparatively less research dealing with robot navigation in unexplored obstacle terrain has been reported in the literature. In recent times this problem has been addressed by adding learning capability to a robot. The robot explores terrain using sensors as it navigates, and builds a terrain model in an incremental manner. In this article we present concurrent algorithms for robot navigation in unexplored terrain. The performance of the concurrent algorithms is analyzed in terms of planning time, travel time, scanning time, and update time. The analysis reveals the need for an efficient data structure to store an obstacle terrain model in order to reduce traversal time, and also to incorporate learning. A modified adjacency list is proposed as a data structure for storing a spatial graph that represents an obstacle terrain. The time complexities of the algorithms that access, maintain, and update the spatial graph are estimated, and the effectiveness of the implementation is illustrated.

Modeling and control of a mobile robot subject to disturbances

Abstract: This work is concerned with the modeling and control of a robot that is mounted on a moving platform. The platform is subjected to random disturbances along its pitch, yaw, and roll axes. A controller is designed so that the robot can carry out tasks with respect to the robot base frame. In general, the problem is to investigate the various modeling and control issues involved in robotic systems subjected to time varying disturbances.

Orientation adjustment system and robot using same

Abstract: This invention features a mobile robot having a body which has an azimuthal angle that is optimally fixed in space and provides the basic reference for the robot to the outside world. The robot further includes a drive system having wheels for enabling movement of the robot, a synchronous steering mechanism which turns the wheels independently of the body, and a head which turns with the wheels. The robot further includes memory for storing the azimuthal angle of the body, a detector assembly disposed in the head for sensing a navigation beacon and resolving an angular deviation between the head and the beacon, and an element for incrementing the stored azimuthal angle by that angular deviation. A system for enabling orientation adjustment is also disclosed.

Pathfinding in multi-robot systems: Solution and applications

Abstract: In the paper a general approach is given to the solution of the findpath problem in multi-robot systems based on a suitable structuring of the hierarchical overall system. The method developed uses a systematic design procedure for multi-robot systems which includes the design of the hierarchical coordinator for on-line collision avoidance. The efficiency of this new approach is demonstrated by several cases like the interaction of three stationary robots with different obstacles as well as by the interaction of mobile robots and moving obstacles.