In recent years, evolution-based knowledge optimization has gained a great deal of popularity due to its inherent ability in efficient and parallel search of complex and multimodal landscapes. Application of genetic a...
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In recent years, evolution-based knowledge optimization has gained a great deal of popularity due to its inherent ability in efficient and parallel search of complex and multimodal landscapes. Application of genetic algorithms (GA) to knowledge enhancement involves several aspects. First is how to code a string to represent all the necessary degrees of freedom for search in the fuzzy knowledge domain. The second aspect is how to incorporate existing expert knowledge into the GA-optimising algorithm. And in general, how to take advantage of several experts' opinions in creation of an initial population. Conventional applications of GA-fuzzy suggest using a random initial population. However, it is intuitively clear that any search routine could converge faster if starting points are good solutions. In this paper, a methodology is illustrated which incorporates expert knowledge in creating an initial population while allowing for randomness among members of the population for diversity. Furthermore, the methodology is applied to step response optimization of a flexible-link feedback control system.
Adaptive behavioral capabilities are necessary for robust navigation in non-engineered environments. A control approach to adaptive behavior is described which exploits the approximate reasoning facility of fuzzy logi...
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Adaptive behavioral capabilities are necessary for robust navigation in non-engineered environments. A control approach to adaptive behavior is described which exploits the approximate reasoning facility of fuzzy logic. In particular, a behavior-based architecture for hierarchical fuzzy control of mobile robots is presented. Its structure is described as well as mechanisms of control decision-making which give rise to adaptive behavior. control decisions result from a consensus of recommendations offered only by behaviors that are applicable to current situations. Indoor navigation examples demonstrate the practicality of the approach and reveals characteristics of multiple behavior interaction.
Adaptive behavioral capabilities are necessary for robust mobile robot navigation in non-engineered environments. Robust behavior requires that uncertainty be accommodated in the robot control system, especially when ...
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Adaptive behavioral capabilities are necessary for robust mobile robot navigation in non-engineered environments. Robust behavior requires that uncertainty be accommodated in the robot control system, especially when autonomy is desired. Fuzzy logic control technology enables development of controllers which can provide the necessary computational intelligence in real-time. This paper presents the incorporation of fuzzy logic, into the framework of behavior-based control. An architecture for hierarchical behavior control is presented in which control decisions result from a consensus of behavioral recommendations. Multiple fuzzy-behavior coordination is discussed and applied to autonomous navigation without explicit maps. Performance and robustness is demonstrated by implementation on a mobile robot with significant mechanical imperfections.
Interlaced systems constitute a class of systems only characterized by the zero entries of their matrix configuration and a local stabilizability condition. All these systems are globally stabilizable by a recursive d...
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ISBN:
(纸本)9783952426906
Interlaced systems constitute a class of systems only characterized by the zero entries of their matrix configuration and a local stabilizability condition. All these systems are globally stabilizable by a recursive design procedure which combines steps of backstepping and forwarding. When a nonlinear system misses this structural characterization, other types of conditions (sign, growth) are needed to ensure global stabilization.
A new approach to stable adaptive fuzzy sliding mode control of systems is proposed. The proposed scheme does not require an accurate mathematical model, yet it guarantees asymptotic stability. It incorporates an inte...
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A new approach to stable adaptive fuzzy sliding mode control of systems is proposed. The proposed scheme does not require an accurate mathematical model, yet it guarantees asymptotic stability. It incorporates an integral term in the sliding surface which eliminates steady state error. To verify the actual performance of the proposed controller, it is then applied to a position control of direct drive motor with payload and parameter uncertainty. Since direct drive motors do not have reduction gears, the variation of the load and the disturbance torque directly influence parameter changes in motor dynamics.
A novel type of electro-optic diffractive element is presented which can satisfy the requirements for a high space-time bandwidth deflector while providing for two-dimensional random access beam steering control. The ...
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ISBN:
(纸本)0819425532
A novel type of electro-optic diffractive element is presented which can satisfy the requirements for a high space-time bandwidth deflector while providing for two-dimensional random access beam steering control. The basic device consists of a multichannel array of phase modulators fabricated using Lanthanum-modified Lead Zirconate Titanate (PLZT) operating as a programmable diffractive optical element. Two-dimensional deflection control can be readily obtained by crossing two one-dimensional arrays. This device is useful for wavelengths in the Visible to Mid-IR range and is based on PLZT ceramic materials which can be readily mass-produced. It possesses the versatility and multifunctionality of liquid crystal based optical phased array systems while allowing for very fast switching speeds with good thermal stability. We present a brief comparison of this novel deflector with other scanning technologies and outline the benefits and trade-offs of the PLZT-based device. Experiments on 16- and 32-channel arrays with fullwave voltages less than 400 volts demonstrate continuous lateral beam steering control of a HeNe laser beam. We also demonstrate full deflection control with a minimum number of control lines using a modified deflector arrangement. And we present measurements showing sub-microsecond switching speeds from such PLZT-based phase modulators. Mature versions of this type of scanner will find use in a wide variety of applications including 2-D and 3-D laser displays, laser communications, and LIDAR systems.
Since direct drive motors do not have reduction gears, the variation of the load and the disturbance torque directly influence parameter changes in motor dynamics. In order to solve this problem, the paper presents a ...
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Since direct drive motors do not have reduction gears, the variation of the load and the disturbance torque directly influence parameter changes in motor dynamics. In order to solve this problem, the paper presents a state feedback adaptive control method for position control of a direct drive motor. The proposed control scheme does not require an accurate mathematical model of the system. The controller consists of a feedforward signal from the desired trajectory based on the inverse system model, feedback from the actual trajectory, and an auxiliary input. The feedforward terms are adjusted by an adaptation law that eliminated the steady-state position errors. In order to compensate for incorrect motor parameters, feedback terms are employed. The auxiliary input is introduced to improve the tracking performance. The proposed controller is applied to position control of a direct drive motor with payload and parameter uncertainty, and the effectiveness is verified by simulation results.
Trajectory control for a reusable launch vehicle (RLV) is considered in the reentry and launch modes. Decoupling sliding mode controllers are designed to achieve the asymptotic tracking of Euler angles' profiles u...
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Trajectory control for a reusable launch vehicle (RLV) is considered in the reentry and launch modes. Decoupling sliding mode controllers are designed to achieve the asymptotic tracking of Euler angles' profiles upon plant uncertainties and external disturbances. Effectiveness of the sliding mode controllers is confirmed by simulations of trajectory tracking in a trimmed condition for the WB001 RLV studied at NASA Marshall Space Flight center.
Trajectory control for a reusable launch vehicle (RLV) is considered for two operational modes: reentry and launch modes are considered. Decentralized sliding mode controllers are designed to achieve the de-coupled as...
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Trajectory control for a reusable launch vehicle (RLV) is considered for two operational modes: reentry and launch modes are considered. Decentralized sliding mode controllers are designed to achieve the de-coupled asymptotic tracking of Euler angles' profiles upon plant uncertainties and external disturbances. Two sliding mode control strategies are investigated: direct Euler angles' profiles tracking and angular rates tracking in combination with a coordinated turn inversion. Effectiveness of the sliding mode controllers is confirmed by simulations of a trajectory tracking for the WB001 RLV studied at NASA Marshall Space Flight center.
The passivity property of dissipative mechanical structures has long been exploited in designing passive controllers that provide robust stability even in the presence of unmodeled dynamics of the system. For an input...
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The passivity property of dissipative mechanical structures has long been exploited in designing passive controllers that provide robust stability even in the presence of unmodeled dynamics of the system. For an input/output map of a flexible structure to be passive, collocation of the actuators and sensors is required and also the sensors should measure the velocity of the system. The so-called smart structures frequently have more sensors than actuators. Therefore, the passive controller can at best utilize only a subset of the sensors. In this paper we consider the design of a squaring down matrix which would render a system passive subject to some additional performance considerations. The problem of obtaining the synthesized passive output is cast as a set of linear matrix inequalities (LMIs) which can be efficiently solved by the LMI Toolbox in Matlab. We apply this procedure with the assumption that the sensors provide both displacement and velocity information which is generally not true. We show that the passive controllers can be implemented without the use of velocity information. By using synthesized passive outputs in addition to naturally occurring passive outputs, we obtain better system performance. We present experimental results involving a single flexible beam with torque input and hub angular position and strain gage outputs.
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