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Sensor-based 3-D autonomous surface-following control

MATHEMATICS AND COMPUTERS IN SIMULATION 1996年第5-6期41卷 429-444页

作者： Nunes, U Faia, P deAlmeida, AT ISR — Institute of Systems and Robotics Electrical Engineering Department University of Coimbra 3000 Coimbra Portugal

Many industrial operations can be automated using robot arms that, however, require the use of robots being able to perform surface-following in an adaptive way. Surface-following in real-time based on sensor information is a delicate task to overtake, yet very useful in operations like painting, welding, glues administration and surface polishing. The surface-following can be accomplished either by using previous knowledge of the shape of the surface, by executing a sequence of movements point-by-point, or in an adaptive way. In the last case a sensor or a set of sensors for collecting data from the environment is used. Furthermore, the surface-following can be characterized by occur with or without robot-surface contact. The paper describes a 3-D surface-following controller. The surface-following operation is performed in real-time, out of contact using proximity information. Experimental results concerning 3-D surface-following movements performed by a PUMA 560 robot are shown.

关键词： Industrial robots

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Pose view stability analysis for camera look angles computation

Pose view stability analysis for camera look angles computat...

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13th International Conference on Pattern Recognition, ICPR 1996

作者： Batista, Jorge Araújo, Helder Almeida, A.T. ISR - Institute of Systems and Robotics Dep. of Electrical Engineering University of Coimbra Coimbra Portugal

ISBN: (纸本)081867282X

The main purpose of this paper is not to present a new camera calibration algorithm or a new pose estimation method, but just to analyse the stability of the camera pose estimation using the Haralick observation which is based on the fact that there is sufficient information on the 2D perspective projection of a rectangle of unknown size in 3D space to determine the three camera look angles. A brief description of the camera look angles computation is presented and a model for the expected stability of the camera look angles computation front noisy image data is described. A stability analysis as a function of the pose of the camera is also described, and the influence of the camera pose is confirmed with simulated data. As a result, camera pose view strategies for accurate camera orientation computation can be extracted from this pose view stability analysis. © 1996 IEEE.

关键词： Cameras

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Fuzzy-based reinforcement learning of a robot force control skill

Fuzzy-based reinforcement learning of a robot force control ...

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IEEE International Symposium on Industrial Electronics (ISIE)

作者： R. Araujo U. Nunes A.T. de Almeida Institute of Systems and Robotics (ISR) Electrical Engineering Department University of Coimbra Coimbra Portugal

Humans perform many tasks with relative ease. In spite of this, many tasks are difficult to model explicitly and it is difficult to design and program automatic control algorithms for them. The development, improvement, and application of learning techniques taking advantage of sensory information would enable the acquisition of new robot skills and avoid some of the difficulties of explicit programming. This paper describes an approach for the generation of skills for the control of multidegree of freedom robotic systems. In the method, the acquisition of skills is done online by self-learning. Instead of generating skills by explicit programming of a perception to action mapping, they are generated by trial and error learning, guided by a performance evaluation feedback function. The structure of the controller consists of two fuzzy subsystems both implemented by feedforward multilayer neural networks. The action fuzzy subsystem has the purpose of generating command actions for the system under control. The evaluation-prediction fuzzy subsystem predicts the future value, a function that evaluates the performance of the controller. Simulation results concerning the application of the approach to learning a robot manipulator force control skill are presented.

关键词： Learning Force control Robot sensing systems Fuzzy control robotics and automation Robot programming Control systems Multi-layer neural network Humans Algorithm design and analysis

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Pose view stability analysis for camera look angles computation

Pose view stability analysis for camera look angles computat...

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International Conference on Pattern Recognition

作者： J. Batista H. Araujo A.T. Almeida ISR-Institute of Systems and Robotics-Department of Electrical Engineering University of Coimbra Coimbra Portugal

关键词： Stability analysis Cameras Calibration Robot vision systems Lenses Robot kinematics Computer vision Algorithm design and analysis Computational modeling Analytical models

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Real-time visual behaviors with a binocular active vision system

Real-time visual behaviors with a binocular active vision sy...

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International Conference on Multisensor Fusion and Integration for Intelligent systems (MFI)

作者： J. Batista P. Peixoto H. Araujo ISR-Institute of Systems and Robotics Department of Electrical Engineering University of Coimbra Coimbra Portugal

An active vision system has to enable the implementation of reactive visual processes and of elementary visual behaviors in real time. In this paper we describe the real-time implementation of several visual behaviors in an active vision system. Issues related to the real-time implementation are discussed, namely in what concerns the modelling of the measurements made in the image. Even though in most applications a fully calibrated system is not required, we also describe a methodology for calibrating the camera head, taking advantage of its degrees of freedom. These calibration parameters are used to evaluate the performance of the system. Another important issue of the operation of active vision binocular heads is their integration into more complex robotic systems. We claim that higher levels of autonomy and integration can be obtained by designing the system architecture based on the concept of purposive behavior. At the lower levels we consider vision as a sensor and integrate it in control systems (both feedforward and servo loops) and several visual processes are implemented in parallel, computing relevant measures for the control process. At higher levels the architecture is modeled as a state transition system. Finally we show how this architecture can be used to implement a pursuit behavior using optical flow. Simultaneously vergence control can also be performed using the same visual processes.

关键词： Real time systems Machine vision Computer architecture Robot vision systems Head Control systems Cameras Calibration Robot sensing systems Sensor systems

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Optoelectronic proximity sensor for robotics applications

Optoelectronic proximity sensor for robotics applications

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Mediterranean Electrotechnical Conference (MELECON)

作者： L. Marques D. Castro U. Nunes A.T. de Almeida ISR-Institute Cor Systems and Robotics Electrical Engineering Department University of Coimbra Portugal

This paper describes an optoelectronic proximity and orientation sensor. We present the sensor modelling and real and simulated results. The sensor is composed by a light emitter and an array of photodetectors that measure the intensity of reflected light on a surface. In this paper we describe the application of this sensor in object prehension tasks performed by a robotic gripper.

关键词： Optoelectronic and photonic sensors Robot sensing systems Sensor arrays Photodetectors Light emitting diodes Sensor systems Optical sensors Sensor phenomena and characterization Tactile sensors Infrared sensors

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A control architecture for active vision systems enabling real time operation

A control architecture for active vision systems enabling re...

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Workshop on Cybernetic Vision

作者： H. Araujo J. Dias J. Batista P. Peixoto Dept. of Electr. Eng. Coimbra Univ. Portugal ISR-Institute of Systems and Robotics Department of Electrical EngineeringFCTUC Institute for Systems and Robotic Coimbra Portugal

An active vision system has to enable the implementation of reactive visual processes and of elementary visual behaviors in real time. Therefore the control architecture is extremely important. In this paper we discuss a number of issues related with the implementation of a real-time control architecture and describe the architecture we are using with our "binocular heads". Another important issue of the operation of active vision binocular heads is their integration into more complex robotic systems. We claim that higher levels of autonomy and integration can be obtained by designing the system architecture based on the concept of purposive behavior. Finally we describe a system where the integration of an active vision stereo head in a mobile robot has been performed, with real-time performance.

关键词： Control systems Machine vision Real time systems Robot vision systems Layout Magnetic heads Mobile robots Visual system Shape Cameras

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Pursuit control in a binocular active vision system using optical flow

Pursuit control in a binocular active vision system using op...

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International Conference on Pattern Recognition

作者： H. Araujo J. Batista P. Peixoto J. Dias Institute of Systems and Robotics Department of Electrical Engineering University of Coimbra Coimbra Portugal

An active vision system must be able to perform reactive visual processes in real time. In this paper we discuss a number of issues related to the implementation of a real-time control architecture and describe the architecture we use with camera heads. Another important issue of the operation of active vision binocular heads is their integration into more complex robotic systems. Higher levels of autonomy and integration can be obtained by designing the control system architecture based on the concept of purposive behavior. At the lower levels we consider the vision as a sensor and integrate it in the control systems (both feedforward and servo loops); and several visual processes are implemented in parallel, computing relevant measures for the control process. At higher levels the architecture is modelled as a state transition system. Finally, we show how this architecture can be used to implement a pursuit behavior using optical flow. Simultaneously vergence control can also be performed using the same visual processes.

关键词： Optical control Control systems Machine vision Computer architecture Optical sensors Robot vision systems Real time systems Cameras Robot sensing systems Sensor systems

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TETROBOT modular robotics: prototype and experiments

TETROBOT modular robotics: prototype and experiments

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IEEE International Workshop on Intelligent Robots and systems (IROS)

作者： G.J. Hamlin A.C. Sanderson Center for Advanced Technology in Automation Robotics and Manufacturing and Department of Electrical Computer and Systems Engineering Rensselaer Polytechnic Institute Troy NY USA

TETROBOT is a modular system for the design, implementation, and control of a class of highly redundant parallel robotic mechanisms. This paper describes new experimental results based on evaluation of prototype configurations with up to 18 nodes, 48 links and 15 actuators. TETROBOT is an actuated robotic structure which may be reassembled into many different configurations while still being controlled by the same hardware and software architecture. Implementations of a double octahedral platform, a tetrahedral arm and a six-legged walker, constructed from the same set of parts, are described. The TETROBOT system addresses the needs of application domains, such as space, undersea, mining, and construction, where adaptation to unstructured and changing environments and custom design for rapid implementation are required.

关键词： Prototypes Collision mitigation robotics and automation Robot sensing systems Manipulators Fasteners Parallel robots Control systems Orbital robotics Manufacturing automation

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Tetrobot family tree: modular synthesis of kinematic structures for parallel robotics

Tetrobot family tree: modular synthesis of kinematic structu...

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IEEE International Workshop on Intelligent Robots and systems (IROS)

作者： A.B. Neville A.C. Sanderson Center for Advanced Technology in Automation Robotics and Manufacturing and Department Electrical Computer and Systems Engineering Rensselaer Polytechnic Institute Troy NY USA

Parallel robots can be built by linking together unit cells in configurations which retain the static determinacy of the overall structure. In the Tetrobot system, the kinematics of these concatenated structures can be solved by propagation of solutions through connected graphs of linked modules. In this paper, we examine the synthesis of unit cells which could be used in creating these structures and retain the ability to compute the kinematics for control of the actuated system. Admissible unit cells are shown to form families in two- and three-dimensions, and a set of synthesis rules is described which generates the members of these families recursively for each generations. The resulting set of modules comprises a broad set of useful cells which can be used to design parallel robots and guarantee the computability of their kinematics on a cell-by-cell basis.

关键词： Kinematics Parallel robots robotics and automation Control system synthesis Manufacturing automation Computer aided manufacturing Concurrent computing systems engineering and theory Joining processes Concatenated codes

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