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Control Systems, IEEE

Issue 4 • Date Aug 1999

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Displaying Results 1 - 5 of 5
  • A hybrid neural control scheme for visual-motor coordination

    Page(s): 34 - 41
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1060 KB)  

    Visual-motor coordination, also referred to as hand-eye coordination, in the context of robotics is the process of using visual information to control a robot manipulator to reach a target point in its workspace. The task requires learning the mapping that exists between camera output and desired end effector location. Biological organisms have demonstrated their superior adaptive capabilities in motion control over present-day robotic systems. Inspired by this fact, various neural network models based on biological systems have been developed for robot control tasks. The drawback of many neural schemes to tackle visual-motor control problems is that of a long training period. We suggest an approach using Kohonen's self-organizing scheme to learn this hand-eye coordination problem in reduced time with high accuracy. Our approach has also been compared with a conventional calibration-based algorithm. These schemes have been implemented in real time on a CRS PLUS robot arm. Experimental results show that the proposed neural scheme is on an average 10 times faster in training compared to similar neural approaches existing in the literature. This speed is also comparable to the conventional algorithm and is more accurate View full abstract»

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  • A multidisciplinary flight control development environment and its application to a helicopter

    Page(s): 22 - 33
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2440 KB)  

    CONDUIT, a computational facility for aircraft flight control design and evaluation, has been developed and demonstrated. CONDUIT offers a graphical environment for integrating simulation models and control law architectures with design specifications and constraints. This tool provides comprehensive analysis support and design guidance to a knowledgeable control system designer. Combining the easy-to-use graphical interface, the preprogrammed libraries of specifications, and the multiobjective function optimization engine (CONSOL-OPTCAD) in a single environment, CONDUIT offers the potential for significant reduction in time and cost of design, analysis, and flight-test optimization of modern flight control systems. A case study application to a complex rotary-wing flight control problem was presented. The baseline RASCAL UH-60 control system, as provided by the flight control contractor, was evaluated versus the ADS-33D handling-quality specifications. The selectable system gains were optimized to meet all system performance and handling-quality specifications. CONDUIT successfully exploited the tradeoff between forward loop and feedback dynamics to significantly improve the expected handling qualities and stability robustness, while reducing crossover frequency and minimizing actuator activity. The tradeoff studies showed the effect of increasing design margin (overdesign) on closed loop performance and actuator activity. Design margins exceeding 7.5% led to rapidly increasing actuator energy and saturation, resulting in shortened fatigue life of rotor control View full abstract»

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  • Supervisory hybrid systems

    Page(s): 42 - 55
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2652 KB)  

    Supervisory hybrid systems are systems generating a mixture of continuous-valued and discrete-valued signals. This systems paradigm is particularly useful in modeling applications where high-level decision making is used to supervise process behavior. Hybrid system methodologies are also applicable to switched systems where the system switches between various setpoints or operational modes to extend its effective operating range. Hybrid systems, therefore, embrace a diverse set of applications. There has been considerable activity in the area of hybrid systems theory, and this article provides an introduction to some of the basic concepts and trends in this emergent field. The term hybrid refers to a mixing of two fundamentally different types of objects or methods. The paper deals with supervisory hybrid systems. Supervisory hybrid systems are systems that combine discrete event and continuous-valued dynamics. The article is organized as follows. We first provide an example of a hybrid system, to be used throughout as a pedagogical tool illustrating various concepts in hybrid systems theory. We then discuss modeling frameworks for hybrid systems, paying specific attention to the hybrid automaton. Not only may the system have a hybrid character, but the specifications on desired system behaviors may also be hybrid. The article also discusses specification logics that express system requirements on both the discrete and continuous states of the system. The article continues with a survey of current methods and concepts used to verify or validate desired system behaviors, and concludes with a survey of current methods for hybrid control system synthesis View full abstract»

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  • Design and implementation of a hybrid control strategy

    Page(s): 12 - 21
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    Hybrid controllers for a double-tank system and a heating/ventilation process have been designed and implemented. Both simulations and real experiments are presented. It is shown that a hybrid controller consisting of a time-optimal controller combined with a PID controller gives very good performance. The controller is easy to implement. It gives, in one of its forms, guaranteed closed loop stability View full abstract»

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  • Swing motion control of casting manipulation

    Page(s): 56 - 64
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    We begin by describing the process of casting manipulation and discussing the swing motion phase. We propose a method of generating the desired swing motion by keeping the string taut from the initial state when the links are hung. We investigate a method for choosing feedback gain using an off-line simulation chart. The method is evaluated by numerical experiments and shown to be effective. We constructed a two-link casting manipulator and conducted an experiment in swing motion control. The experimental results show that the proposed method of swing motion control was effective View full abstract»

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