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This brief presents a new conditioning-transfer-digital-design scheme for continuous-time systems with saturating actuators. The newly developed conditioning dual-rate digital-redesign scheme consists of a slow-rate digital-redesign technique for reducing the windup effects and a conditioning fast-rate digital-redesign technique for systematically reducing the bump-transfer effects. The developed conditioning digitally redesigned trackers are able to be implemented using digital processors and enable us to improve the performance of digitally controlled hybrid systems with saturating actuators. Index Terms--Conditioning scheme, digital redesign, sampled-data control, saturating actuators.

In this paper, the authors propose a systematic approach to determine the exact stability bound of singularly perturbed discrete-time systems. By combining three conditions of the critical stability criterion with a bialternate product for discrete-time systems, the stability problems of two types of singularly perturbed discrete-time systems can be solved via the derived scheme. Several examples are given to illustrate the proposed results. Index Terms: Singular perturbation parameter, singularly perturbed discrete-time systems, stability bound, state-space approach.

The singularity problem of a 7-degrees-of-freedom (DOF) redundant manipulator is analyzed, and a new resolution method is proposed. In this paper, the singularities are decoupled into the position singularities and the orientation singularity by the technique of workspace decomposition, then ali sigularity conditions for both cases are derived, and the new singularity avoidance (NSA) method is proposed. The NSA method resolves the escapable singularities which can be reconfigured into a nonsingular posture via self motion. Unlike some existing methods, the NSA method considers the position singularities and the orientation singularity separately. This method only needs to optimize two order-3 minors, one for the 3 x 4 Jacobian translational submatrix and the other for the 3 x 7 Jacobian rotational submatrix. Therefore, the computation for the optimization is greatly reduced. Three examples are presented to demonstrate the generality and efficiency of this new method. Index Terms - Redundant manipulator, singularity, workspace decomposition.

The present paper is concerned with the decentralized stabilization problem of large-scale systems with delays in the interconnections using sliding mode control. A robust stability condition of the sliding mode and a robust decentralized sliding mode controller are newly derived for large-scale delay systems. Also a proportional-integral sliding mode is designed to make it easy to assure the stability of dynamics in the sliding mode.

In this paper, based on Lyapunov stability theorem, matrix measure, and norm inequalities, a new approach for the robust stability of perturbed systems with a class of noncommensurate time delays is presented. Two classes of linear parametric perturbations are treated: (1) unstructured and (2) highly structured perturbations. Several concise sufficient conditions, delay-dependent or delay-independent, are proposed to guarantee the asymptotic stability and positive stability degree of the perturbed multiple time-delay systems. Finally, two numerical examples are given to demonstrate the applications of these quantitative results.

A stability criterion for uncertain systems with time-varying delay is derived via the Lyapunov functional approach. By checking the Hamiltonian matrix and solving an algebraic Riccati equation, a new bound on allowable stability preserving nonlinear perturbations is presented. The result obtained here is shown to be less conservative than others reported in the literature. Index Terms--Robust stability, time-delay systems, uncertain systems.

This paper presents two kinds of robust controllers for stabilizing singularly perturbed discrete bilinear systems. The first one is an [Epsilon]-dependent controller that stabilizes the closed-loop system for all [Epsilon] [element of] ([MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]) where [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] is the prespecified upper bound of the singular perturbation parameter. The second one is an [Epsilon]-independent controller, which is able to stabilize the system in the entire state space for all [Epsilon] [element] (0, [Epsilon]*, where [Epsilon]*] is the exact upper [Epsilon]-bound. The [Epsilon]* can be calculated by the critical stability criterion once the robust controller is determined. An example is presented to illustrate the proposed schemes. Index Terms--Lyapunov equation, robust controller, singularly perturbed discrete bilinear systems, singular perturbation parameter.

According to the Lyapunov stability theorem and the bounds of solutions of the Lyapunov equation, the state feedback gain matrices can be determined to guarantee the stability of the singularly perturbed systems for all [Epsilon] [element of] (0, [infinity]). A numeral example and an operational amplifier circuit are given to illustrate the effectiveness of the proposed scheme. Index Terms--Lyapunov equation, Lyapunov function, singular perturbation parameter, singularly perturbed systems.

Presents information on a study which tested the effectiveness of the Lyapunov stability theorem and equation for the stabilization of singularly perturbed systems. System description and problem formulation; Design procedure; Conclusions.

The two-level hierarchical control scheme is adopted to solve a dual-chain robotic system formed by two redundant manipulators grasping a common object with hard point contacts. The upper-level coordinator gathers all the necessary information to resolve the force distribution problem so as to generate all the desired contact forces. With all the desired contact forces being specified, the dynamics of each chain are decoupled. Therefore, the lower-level local control problem can be treated as a general open-chain redundant manipulator problem. Furthermore, the Compact-Dual LP method is applied to resolve the upper-level coordination problem; while the Compact QP method associated with the computed torque control method is adopted to solve the redundant manipulator problem. To obtain proper simulation results, the simulated actual contact forces are formulated and the corresponding simulation problem of the closed-chain robotic system is also completely solved in the article. Simulation results show that the two-level hierarchical control scheme is an effective and efficient algorithm for resolving the large-scale control problem of multiple-chain robotic systems. © 1995 John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]