A special active compliance law is presented as the feedback element in a non-master/slave (i.e. symmetric) coordination strategy with explicit force distribution for robots with multiple cooperating arms. The method ...
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It is shown that on the set of m-input, p-output asymptotically stable, minimal, nth order systems that the H∞pxm and the RN quotient induced topologies coincide. Implications of this in frequency domain system ident...
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Some issues and results in computer-aided control system design (CACSD) for time-varying systems are discussed. Time-varying plants and controllers, representation of systems by models and special operators, and the e...
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Some issues and results in computer-aided control system design (CACSD) for time-varying systems are discussed. Time-varying plants and controllers, representation of systems by models and special operators, and the existence, gain scheduling and convex optimization of a control are discussed.< >
A massively redundant, tentacle-based robot manipulator is proposed as an alternative to dextrous manipulation by an arm/hand combination. The tentacle is advantageous because it is an all-in-one arm and gripping devi...
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A massively redundant, tentacle-based robot manipulator is proposed as an alternative to dextrous manipulation by an arm/hand combination. The tentacle is advantageous because it is an all-in-one arm and gripping device capable of a wide variety of configurations and grasps, while maintaining the mechanics of serial manipulators. A method for evaluating the forces and velocities imparted to an arbitrary object by a robot hand is reviewed and extended to include the case where several serial manipulators each come in contact with an object at multiple joints. From this analysis, a quantitative evaluation of grasp manipulability and stability is developed that accounts for multiple object contacts for each serial manipulator in the system. A method of applying both precision and power grasps to three-dimensional objects using a tentacle is presented that allows for easy transition between the two by merely curling or uncurling links from around the object. This method helps reduce the number of complexity of grasp configurations. Numerical simulations of different tentacle manipulators and grasps are given.< >
A rule-based fuzzy control method is proposed in this paper for the control of single-link, lightweight, flexible manipulators. The objective of this method is to control the tip position of a flexible manipulator in ...
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A rule-based fuzzy control method is proposed in this paper for the control of single-link, lightweight, flexible manipulators. The objective of this method is to control the tip position of a flexible manipulator in the presence of joint friction and changes in the payload. Both linear and nonlinear friction are overcome using a robust control scheme. The control scheme is based on two nested feedback loops: an inner loop to control the position of the motor and an outer loop to control the tip position. The tip position is controlled by a rule-based fuzzy controller. This results in a simple control law that needs minimal computing effort and can be used for real-time control of flexible arms.
Given a linear, time-invariant, discrete-time plant, we consider the optimal control problem of minimizing, by choice of a stabilizing compensator, the seminorm of a selected closed-loop map in a basic feedback system...
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Given a linear, time-invariant, discrete-time plant, we consider the optimal control problem of minimizing, by choice of a stabilizing compensator, the seminorm of a selected closed-loop map in a basic feedback system. The seminorm can be selected to reflect any chosen performance feature and must satisfy only a mild condition concerning finite impulse responses. We show that if the plant has no poles or zeros on the unit circle, then the calculation of the minimum achievable seminorm is equivalent to the maximization of a linear objective over a convex set in a low-dimensional Euclidean space. Hence, for a wide variety of optimal control problems, one can compute the answer to an infinite-dimensional optimization by a finite-dimensional procedure. This allows the use of effective numerical methods for computation.
A new method for the model reduction of finite-dimensional, linear, time-invariant (FDLTI) plants is given. The method uses fractional representation theory to extend balance and trancate model reduction to unstable p...
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A new method for the model reduction of finite-dimensional, linear, time-invariant (FDLTI) plants is given. The method uses fractional representation theory to extend balance and trancate model reduction to unstable plants without requiring the ad-hoc division of the plant into stable and completely unstable parts. The new method, dubbed fractional balanced reduction or FBR, applies balance and truncate to a special representation of the graph operator of the plant. This operation yields an object readily recognized as the graph operator of a reduced order plant. The method has nice properties including existence of an a priori error bound in the graph metric, and preservation of sector containment which is useful for deciding system stability when nonlinearities are present.
A class of linear, shift-varying operators that generalizes the notion of N-periodicity is defined. It is shown that shift-invariant equivalents for these operators exist, and that the equivalence is in a strong sense...
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A class of linear, shift-varying operators that generalizes the notion of N-periodicity is defined. It is shown that shift-invariant equivalents for these operators exist, and that the equivalence is in a strong sense, preserving both algebraic and analytic systems properties. It is shown that multi-rate sampled-data systems, though not generally periodic, fall into this class. Kranc vector switch decomposition and block filter implementations for single-input, single-output multi-rate systems are connected under the unifying framework of shift-invariant equivalents, and this framework is the way to extend them both to multi-input, multi-output systems. Possible applications include a parameterization of all stabilizing multi-rate controllers.< >
The author presents a novel computer-aided-design method for multi-rate sampled-data feedback systems (MRSDFSs) with many nice features including naturalness and effectiveness. Naturalness means that a control enginee...
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The author presents a novel computer-aided-design method for multi-rate sampled-data feedback systems (MRSDFSs) with many nice features including naturalness and effectiveness. Naturalness means that a control engineer can express specifications in his terms, by referring directly to signal peaks, overshoots, RMS powers, pulse responses, etc., rather than other, less direct (and more opaque) expressions (e.g. a quadratic integral in LQR or LQG). Effectiveness means that if a controller meeting the specifications exists, then the method will find it. The three main concepts for the proposed MRSDFS CAD method are: (1) shift-invariant representations for multi-rate systems; (2) parametrization of stabilizing controllers and convexity of specifications; and (3) machine intelligence and control specification language compilers. Rather than rigorously discussing each topic in depth and full generality, the author chooses a simple example and discusses each concept as it arises in the course of designing a MRSDFS.< >
Trajectory planning methods and control algorithms for biped robot steady walking are discussed. The model following plus variable structure systems technique is developed for the control of dynamic walking in the sag...
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Trajectory planning methods and control algorithms for biped robot steady walking are discussed. The model following plus variable structure systems technique is developed for the control of dynamic walking in the sagittal plane. The nonlinear feedback plus modified alpha -computed torque technique is introduced for walking in the frontal plane. simulation results are provided for level walking and ascending on staircases for a five-link biped robot. These results indicate that the proposed algorithms could achieve robust trajectory tracking even in the presence of system modeling errors. Specifically, simulation results show that, even in the presence of disturbances, gait stability can be achieved within two steps after the start of walking. In addition, the biped robot can walk with prespecified patterns.< >
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