Showing papers on "Robot published in 1989"

Robot vision

Abstract: A scheme is developed for classifying the types of motion perceived by a humanlike robot. It is assumed that the robot receives visual images of the scene using a perspective system model. Equations, theorems, concepts, clues, etc., relating the objects, their positions, and their motion to their images on the focal plane are presented. >

Real-time obstacle avoidance for fast mobile robots

Abstract: A real-time obstacle avoidance approach for mobile robots has been developed and implemented. It permits the detection of unknown obstacles simultaneously with the steering of the mobile robot to avoid collisions and advance toward the target. The novelty of this approach, entitled the virtual force field method, lies in the integration of two known concepts: certainty grids for obstacle representation and potential fields for navigation. This combination is especially suitable for the accommodation of inaccurate sensor data as well as for sensor fusion and makes possible continuous motion of the robot with stopping in front of obstacles. This navigation algorithm also takes into account the dynamic behavior of a fast mobile robot and solves the local minimum trap problem. Experimental results from a mobile robot running at a maximum speed of 0.78 m/s demonstrate the power of the algorithm. >

A new technique for fully autonomous and efficient 3D robotics hand/eye calibration

Abstract: The authors describe a novel technique for computing position and orientation of a camera relative to the last joint of a robot manipulator in an eye-on-hand configuration. It takes only about 100+64N arithmetic operations to compute the hand/eye relationship after the robot finishes the movement, and incurs only additional 64 arithmetic operations for each additional station. The robot makes a series of automatically planned movements with a camera rigidly mounted at the gripper. At the end of each move, it takes a total of 90 ms to grab an image, extract image feature coordinates, and perform camera extrinsic calibration. After the robot finishes all the movements, it takes only a few milliseconds to do the calibration. A series of generic geometric properties or lemmas are presented, leading to the derivation of the final algorithms, which are aimed at simplicity, efficiency, and accuracy while giving ample geometric and algebraic insights. Critical factors influencing the accuracy are analyzed, and procedures for improving accuracy are introduced. Test results of both simulation and real experiments on an IBM Cartesian robot are reported and analyzed. >

Grasping and Coordinated Manipulation by a Multifingered Robot Hand

Abstract: A new avenue of progress in the area of robotics is the use of multifingered robot hands for fine motion manipulation. This paper treats two fundamental problems in the study of multi fingered robot hands: grasp planning and the determination of coordinated control laws with point contact models. First, we develop the dual notions of grasp stability and grasp manipulability and propose a procedure for task modeling. Using the task model, we define the structured grasp quality measures, and using these measures we then devise a grasp planning algorithm. Second, based on the assumption of point contact models, we develop a computed torque-like con trol algorithm for the coordinated manipulation of a multi fingered robot hand. This control algorithm, which takes into account both the dynamics of the object and the dynamics of the hand, will realize simultaneously both the position trajec tory of the object and any desired value of internal grasp force. Moreover, the formulation of the control scheme can be e...

Global path planning using artificial potential fields

Abstract: The author describes a path planning technique for robotic manipulators and mobile robots in the presence of stationary obstacles. The planning consists of applying potential fields around configuration-space obstacles and using these fields to select a safe path for the robot to follow. The advantage of using potential fields in path planning is that they offer a relatively fast and effective way to solve for safe paths around obstacles. In the proposed method of path planning, a trial path is chosen and then modified under the influence of the potential field until an appropriate path is found. By considering the entire path, the problem of being trapped in a local minimum is greatly reduced, allowing the method to be used for global planning. The algorithm was tried with success on many different realistic planning problems. By way of illustration, the algorithm is applied to a two-dimensional revolute manipulator, a mobile robot capable of translation only, and a mobile robot capable of both translation and rotation. >

Visual navigation and obstacle avoidance structured light system

Abstract: A vision system for a vehicle, such as a mobile robot (10) includes at least one radiation projector (14, 16) which projects a structured beam of radiation into the robot's environment. The structured beam of radiation (14a, 16a) preferably has a substantially planar pattern of sufficient width to encompass the immediate forward path of the robot and also to encompass laterally disposed areas in order to permit turning adjustments. The vision system further includes an imaging (12) sensor such as a CCD imaging device having a two-dimensional field of view which encompasses the immediate forward path of the robot. An image sensor processor (18) includes an image memory (18A) coupled to a device (18D) which is operable for accessing the image memory. Image processing is accomplished in part by triangulating the stored image of the structured beam pattern to derive range and bearing, relative to the robot, of an object being illuminated. A navigation control system (20) of the robot inputs data from at least the vision system and infers therefrom data relating to the configuration of the environment which lies in front of the robot. The navigation control system generates control signals which drive propulsion and steering motors in order to navigate the robot through the perceived environment.

Real-time application of neural networks for sensor-based control of robots with vision

Abstract: A practical neural network-based learning control system is described that is applicable to complex robotic systems involving multiple feedback sensors and multiple command variables. In the controller, one network is used to learn to reproduce the nonlinear relationship between the sensor outputs and the system command variables over particular regions of the system state space. The learned information is used to predict the command signals required to produce desired changes in the sensor outputs. A second network is used to learn to reproduce the nonlinear relationship between the system command variables and the changes in the video sensor outputs. The learned information from this network is then used to predict the next set of video parameters, effectively compensating for the image processing delays. The results of learning experiments using a General Electric P-5 manipulator are presented. These experiments involved control of the position and orientation of an object in the field of view of a video camera mounted on the end of the robot arm, using moving objects with arbitrary orientation relative to the robot. No a priori knowledge of the robot kinematics or of the object speed of orientation relative to the robot was assumed. Image parameter uncertainty and control system tracking error in the video image were found to converge to low values within a few trials. >

Deadlock-free and collision-free coordination of two robot manipulators

Abstract: The authors describe a method for coordinating the trajectories of two robot manipulators so as to avoid collisions between them. It is assumed that the robots' environment is known and that the robots' paths can thus be planned in advance but that there may be significant variations in the execution time of some of the path segments. The goal is to allow the motions of each manipulator to be planned nearly independently and to allow the execution of the path segments to be asynchronous. The coordination is achieved by introducing explicit coordination commands into the path. The key problems in coordinating trajectories are to avoid collisions between the two robots and to avoid deadlock, that is, situations where each manipulator is waiting for the other to proceed. >

Three dynamic problems in robot force control

Abstract: Three dynamic problems which arise in robot systems are discussed: rigid-body bandwidth; dynamically noncolocated flexible modes; and dynamically colocated flexible modes. These effects combine to set the closed-loop bandwidth achievable in the individual joint control loops. Simple models of robot systems are presented to illustrate these three dynamic effects. Some laboratory data are then presented and analyzed in these terms. Finally, the implications for robot system design is discussed in the hope that these issues will be considered in the development of the next generation of robot systems and machine tools. >

Fast, Cheap and Out of Control: a Robot Invasion of the Solar System

Abstract: Complex systems and complex missions take years of planning and force launches to become incredibly expensive. The longer the planning and the more expensive the mission, the more catastrophic if it fails. The solution has always been to plan better, add redundancy, test thoroughly and use high quality components. Based on our experience in building ground based mobile robots (legged and wheeled) we argue here for cheap, fast missions using large numbers of mass produced simple autonomous robots that are small by today's standards (1 to 2 Kg). We argue that the time between mission conception and implementation can be radically reduced, that launch mass can be slashed, that totally autonomous robots can be more reliable than ground controlled robots, and that large numbers of robots can change the tradeoff between reliability of individual components and overall mission success. Lastly, we suggest that within a few years it will be possible at modest cost to invade a planet with millions of tiny robots.

A formal model of computation for sensory-based robotics

Abstract: It is noted that almost all attempts to construct special-purpose robot programming languages have proceeded by taking a computer-programming language and adding some special primitives. Here, the authors have taken the approach of trying to define computation at its most primitive level in terms of the characteristics of the robot domain. They construct a special model of computation, called RS (robot schemas), with properties designed to facilitate sensory-based robot programming. This approach offers the potential to construct robot task representations which are easy to use and concise, and which execute in an efficient manner. The authors define the model formally using port automata. These definitions ensure consistency and well-definedness, and the facilitate plan verification and automatic plan generation. >

Fast motion planning for multiple moving robots

Abstract: The author presents an efficient solution to the motion-planning problem for multiple translating robots in the plane. It is shown that careful priority assignment can greatly reduce the average running time of the planner. A priority assignment method is introduced which attempts to maximize the number of robots which can move in a straight line form their start point to their goal point, thereby minimizing the number of robots for which expensive collision-avoiding search is necessary. This prioritization method is extremely effective in sparse workspaces where the moving robots are the primary obstacle. >

A robot that walks; emergent behaviors from a carefully evolved network

Abstract: The author describes a carefully designed series of networks, each one being a strict augmentation of the previous one, which control a six-legged walking machine capable of walking over rough terrain and following a person passively sensed in the infrared spectrum As the completely decentralized networks are augmented, the robot's performance and behavior repertoire demonstrably improve The rationale for such demonstrations is that they can help identify requirements for automatically building massive networks to carry out complex sensory-motor tasks The experiments with an actual robot ensure that an essence reality is maintained and that no critical disabling problems have been ignored The present work is based on the drawing of analogies between evolution in the animal world and robotic evaluation >

Adaptive control of flexible joint manipulators

Abstract: The authors present an adaptive control result for flexible-joint robot manipulators. Under the assumption of weak joint elasticity, a singular perturbation argument is used to show that recent adaptive control results for rigid robots can be used to control flexible-joint robots, provided a simple correction term is added to the control law to damp out the elastic oscillations at the joints. In this way, fundamental properties of rigid robot dynamics can be used to design robust adaptive control laws for flexible-joint robots. The implementation of the full controller requires only joint position and velocity information. Thus, robustness to parametric uncertainty is achieved without the need for acceleration and jerk measurements. >

Design Of An Autonomous And Distributed Robot System: Actress

Abstract: A new concept of an advanced robot system, ACTRESS (ACTor-based Robots and Equipments Synthetic System), is presented in this paper. ACTRESS is an autonomous and distributed robot system composed of multi robotic elements. Each element is provided with functions to make decisions with understanding the target of tasks, recognizing surrounding environments, acting, and managing its own conditions, and to communicate with any other components. In order to manage multiple elements to achieve any given task targets, the protocol for communication between elements is discussed for cooperative action between arbitrary elements. This paper deals with the conceptual design of ACTRESS, focusing on the methodology for synthesizing the autonomous and distributed system. Also based on an assumption that mobility is the indispensable function for advanced robot systems, an experimental system using micro mouse"'^ is developed as a primitive example of ACTRESS.

Task-level planning of pick-and-place robot motions

Abstract: A task-level robot system named Handey, which is under development, is described. The current system is limited to pick-and-place operations, and it has successfully carried out dozens of such operations involving a variety of parts in relatively complex environments. The pick-and-place problem is described, and approximate approaches to the problem are examined. Heuristic motion planning in Handey is then discussed. >

Inverse kinematics of redundant robots using genetic algorithms

Abstract: Genetic algorithms, which are robust general-purpose optimization techniques, have been used to solve the inverse kinematics problem for redundant robots. A genetic algorithm (GA) was used to position a robot at a target location while minimizing the largest joint displacement from the initial position. As currently implemented, GAs are suitable for offline programming of a redundant robot in point-to-point positioning tasks. The GA solution needs only the forward kinematic equations (which are easily developed) and does not require any artificial constraints on the joint angles. The joint rotation limits which are present in any feasible robot design are handled directly; so any solution determined by the GA is physically realizable. Finally, the GA works with joint angles represented as digital values (not continuous real numbers), which is more representative for computer-controlled robot systems. >

Adaptive control of flexible-joint manipulators

Abstract: Under the assumption of weak joint elasticity, a singular perturbation argument is used to show that recent adaptive control results for rigid robots can be used to control flexible-joint robots provided a simple correction term is added to the control law to damp out the elastic oscillations at the joints. In this way, fundamental properties of rigid robot dynamics can be exploited to design adaptive control laws for flexible-joint robots that are robust to parametric uncertainty. Experimental results are given to illustrate the theory. >

Sensor fusion in certainty grids for mobile robots

Abstract: A numeric representation of uncertain and incomplete sensor knowledge called certainty grids was used successfully in several recent mobile robot control programs developed at the Carnegie-Mellon University Mobile Robot Laboratory (MRL). Certainty grids have proven to be a powerful and efficient unifying solution for sensor fusion, motion planning, landmark identification, and many other central problems. MRL had good early success with ad hoc formulas for updating grid cells with new information. A new Bayesian statistical foundation for the operations promises further improvement. MRL proposes to build a software framework running on processors onboard the new Uranus mobile robot that will maintain a probabilistic, geometric map of the robot's surroundings as it moves. The certainty grid representation will allow this map to be incrementally updated in a uniform way based on information coming from various sources, including sonar, stereo vision, proximity, and contact sensors. The approach can correctly model the fuzziness of each reading and, at the same time, combine multiple measurements to produce sharper map features; it can also deal correctly with uncertainties in the robot's motion. The map will be used by planning programs to choose clear paths, identify locations (by correlating maps), identify well-known and insufficiently sensed terrain, and perhaps identify objects by shape. The certainty grid representation can be extended in the time dimension and used to detect and track moving objects. Even the simplest versions of the idea allow us to fairly straightforwardly program the robot for tasks that have hitherto been out of reach. MRL looks forward to a program that can explore a region and return to its starting place, using map "snapshots" from its outbound journey to find its way back, even in the presence of disturbances of its motion and occasional changes in the terrain.

An Experimental System for Incremental Environment Modelling by an Autonomous Mobile Robot

Abstract: Incremental map-making is a necessary function of an autonomous mobile robot Sensor data are always imprecise, and in the case of a mobile robot, sensor location is itself imprecise and even sometimes false (eg in case of slippage) We show how sensors data inaccuracies can be processed to produce a consistent environment model and an as precise as possible robot positioning The experimental system (a mobile robot with a laser range finder and odometry) is presented and the theoretical approach is applied on actual data

Inversion Techniques for Trajectory Control of Flexible Robot Arms

Abstract: A general framework is given for computing the torques that are needed for moving a flexible arm exactly along a given trajectory. This torque computation requires a dynamic generator system, as opposed to the rigid case, and can be accomplished both in an open- or in a closed-loop fashion. In the open-loop case, the dynamic generator is the full or reduced order inverse system associated to the arm dynamics and outputs. In order to successfully invert the arm dynamics, the torque generator should be a stable system. The stability properties depend on the chosen system output, that is on the robot variables (e.g., joint or end-effector) to be controlled. The same inversion technique can be applied for closed-loop trajectory control of flexible robots. A simple but meaningful nonlinear dynamic model of a one-link flexible arm is used to illustrate different feasible control strategies. Simulation results are reported that display the effects of the system output choice on the closed-loop stability and on the overall tracking performance.

On nonholonomic mobile robots and optimal maneuvering

Abstract: The authors consider the robot path planning problem in the presence of nonintegrable kinematic constraints, known as nonholonomic constraints. Such constraints are generally caused by one or several rolling contacts between rigid bodies and express that the relative velocity of two points in contact is zero. They make the dimension of the space of achievable velocities smaller than the dimension of the robot's configuration space. Using standard results in differential geometry (Frobenius integrability theorem) and nonlinear control theory, the authors first give a formal characterization of holonomy (and nonholonomy) for robot systems subject to linear differential constraints and state some related results about their controllability. They then apply these results to 'car-like' and 'trailer-like' robots. Finally, they present an implemented planner, which generates collision-free paths with a minimal number of maneuvers for car-like and trailer-like robots among obstacles. >

Optimal Load Distribution for Two Industrial Robots Handling a Single Object

Abstract: The load distribution problem for two coordinating industrial robots handling a single object is studied. When two industrial robots grasp a single object, the total number of degrees of freedom is usually greater than six. Thus, the joint torques of two robots for a required motion of the object is not unique. The redundant degrees of freedom may be used to optimize certain kind of performance. The least energy consumption is selected as the optimization criterion. Optimal algorithms without and with a bound on the joint torques are investigated. The results show that the algorithms are computationally complicated and not suitable for real-time applications. Alternatively, optimal algorithms are proposed for load distribution with minimum exerted forces on the object. These algorithms require less computational time, which makes them attractive for real-time applications. >

The robotics review 1

Abstract: Part 1 Programming, planning, and learning: articles - motion planning in the presence of moving obstacles, Jean-Claude Latombe, minimal length curves and optimal paths, Jean-Daniel Boissonat, task level robot programming - on the HANDEY system, Jocelyne Pertin-Troccaz reviews - robot motion planning, Jean-Claude Latombe, John Canny, planar sliding with dry friction, Suresh Goyal, et al. Part 2 Sensing and perception: articles - touch sensing for robotic manipulation and recognition, Robert D. Howe and Mark R. Cutkosky, sensor planning for robotic vision - a review, Konstantinos (Dino) Tarabanis and Rober Y. Tsai, solving for 3-D model parameters from the locations of image features, David Lowe, modeling sonar sensors, Hugh F. Durrant-Whyte and John J. Leonard reviews - authenticating edges produced by zero-crossing algorithms, James J. Clark and Harlyn Baker a few steps toward artificial 3-D vision, Olivier D. Faugeras, W. Eric L. Grimson. Part 3 Kinematics and dynamics: articles - wrist singularities - theory and practice, Charles Wampler reviews - kinematic analysis and design of redundant manipulators, Joel W. Burdick and Vincent Hayward, singular configurations of parallel manipulators and Grassman geometry, Jean-Pierre Merlet and Jorge Angeles, a spatial operator algebra for manipulator modeling and control, G. Rodriquez, et al on the inverse kinematics of redundant manipulators, Daniel R. Baker, et al duality in mechanical properties of sequential and parallel manipulators, Vladimir Zamanov, et al. Part 4 Motion and force control: articles - time-optimal motions of robot manipulators including dynamics, Marc Renaud and J. Yves Fourquet, the state of the art of robot learning control using artificial neural networks - an overview, V.D. Sanchez A. and G. Hirzinger reviews - the application of model-referenced adaptive control to robotic manipulators, S. Dubowsky, et al is adaptive control necessary for manipulation robots, and if so, to what extent?, D. Stokic, et al. Part 5 Design, technology, and applications: articles - a comparative analysis of actuator technologies for robotics, John M. Hollerback, et al, microrobotics - shifting robotics technology toward a different scale world, Paolo Dario and Renzo Valleggi reviews - robotics in service, Joseph F. Engelberger and Russell H. Taylor.

Robotics in Service

Abstract: Robots can play a major role in the service industries. And it is in that direction that robotics needs to turn, Joseph Engleberger asserts, not toward the routine factory jobs of the past. Engleberger was instrumental in founding the robotics industry and his book Robotics in Practice is now a classic. In Robotics in Service he observes that the time is ripe for robotics to launch itself into an entirely new marketplace.Engelberger's starting point is the fact that it is now feasible to equip robots with a wide repertoire of senses and to provide them with at least rudimentary intelligence. We can produce a range of robotic devices that can be put to work performing a variety of services that have become increasingly unattractive to the human labor force because of their mundane nature or the dangers they involve.Part I of the book provides a robotics technology update, concentrating on the new developments, particularly in sensory equipment and artificial intelligence. Part II examines in detail 15 specific applications - ranging from commercial cleaning and fast food service to jobs in space and aid for the handicapped and the elderly - that are ripe for exploitation.Joseph F. Engelberger was the founder of Unimation, the first manufacturer of industrial robots in the world. He is a past president of the Robot Institute of America and currently Chairman of Transition Research Corporation

A Colony Architecture for an Artificial Creature

Abstract: This report describes a working autonomous mobile robot whose only goal is to collect and return empty soda cans. It operates in an unmodified office environment occupied by moving people. The robot is controlled by a collection of over 40 independent ``behaviors'''' distributed over a loosely coupled network of 24 processors. Together this ensemble helps the robot locate cans with its laser rangefinder, collect them with its on-board manipulator, and bring them home using a compass and an array of proximity sensors. We discuss the advantages of using such a multi-agent control system and show how to decompose the required tasks into component activities. We also examine the benefits and limitations of spatially local, stateless, and independent computation by the agents.

Predictive and knowledge-based telerobotic control concepts

Abstract: The problems that arise when sensor-controlled robots in space are teleoperated from ground stations are discussed. A supervisory control concept is described that makes it possible to realize shared control between teleoperator and sensor-controlled robot in a variety of configurations. Predictive 3D computer graphics currently seems to be the only way to cope successfully with the problem of transmission-time delays of several seconds. Appropriate estimation schemes in combination with knowledge-based world modeling are outlined, which include models of the delay lines, the robot, moving objects, etc., and which derive the necessary updates from sensory data as they are sent down from the spacecraft to earth (e.g. via real-time stereo vision). The space robot technology experiment Rotex scheduled for the next German Spacelab mission (2D) is taken as a basis for the problem description. >

Coordinated motion control of robot arms based on the virtual internal model

Abstract: The authors propose an alternative coordinated motion control architecture for robot arms manipulating an object. The motion and the internal force of the object are resolved into the motion of each arm. Each arm is controlled, on the basis of the virtual internal model, so that they operate in coordination even if geometric errors exist in the arms and the object. The virtual internal model is a reference model driven by sensory information implemented in the controller. The proposed architecture maintains the stability of the system even if breakage of the manipulated object occurs. The control algorithm was experimentally applied to the coordinated motion control of two planar robot arms, each of which has three degrees of freedom. The results illustrate the validity of the proposed control architecture. >