摘要:

A new scheduling technique is presented for scheduling local nonlinear control laws. This leads to a new nonlinear design method for regulation of flight control systems. First, nonlinear feedback controls are designed using a nonlinear optimal control design method at a number of operating points (i.e. different Mach numbers). Then these nonlinear control laws are scheduled in a particular way according to the forward speedu. The resulting control law still takes the form of a static nonlinear control and is such that deviation in forward speedu(the scheduling variable) from the trim value does not affect control of the short period variables. This nice property can be retained over the entire flight envelope. The well-studied F-8 aircraft is used for this study. Computer simulations are given to show the effectiveness of this nonlinear control design method. Robustness to variations in system parameters is also studied by simulation.

ISSN:0020-7179    

DOI:10.1080/00207179508921929

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This paper addresses the steering control problem formulation for path following in the plane motion of a class of low-speed ground vehicle that can be modelled as a tricycle. After a short discussion about the error correction mechanism, the equations of motion are obtained based on the system kinematics. These equations govern the characteristics of the control system of the steering action in terms of the two measurable position and orientation errors associated with path following. Two important results are derived. It is indicated that for path following, for this class of vehicle at low speeds, the equations of motion based on system kinematics are sufficient for control purposes. Furthermore, if the differential point (the rear axle middle point) is considered for position error measurement, then the equations governing the steering action in such a vehicle are similar to those of a double integrator.

ISSN:0020-7179    

DOI:10.1080/00207179508921930

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

In this paper, a method is proposed for designing the command feedforward controller for zero phase error tracking control of systems having unacceptable zeros. The unacceptable zeros include both non-minimum phase zeros and lightly damped zeros. In the proposed approach, a digital preview filter along with the acceptable part of the system's inverse model is designed to form the command feedforward controller. Using preview information of the input trajectory, the designed tracking controller guarantees zero phase error and high precision tracking performance. In the proposed design, the best tracking performance can be achieved by minimizing a weighted penalty function, which controls the gain error between the desired output and the actual output. Two design cases were examined. The first is the design based on a uniform weighting function. In this study, the optimal solution of the design can be analytically obtained and three prior approaches were shown to be the special cases of the proposed solution. The second case is the design based on input trajectory. It was shown that in the trajectory-based design, the proposed penalty function in the frequency domain is, in fact, the total squared tracking errors in the time domain. Therefore, the proposed digital preview filter based on input trajectory is the optimal solution in achieving the best tracking performance.

ISSN:0020-7179    

DOI:10.1080/00207179508921931

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The use of the internal model principle (IMP, absorption principle) and internal model control (IMC) together is investigated. The design constructively achieves both robust stability and disturbance rejection. A comparison with one-degree-of-freedom IMC is made. The advantage over IMC is in the treatment of the disturbance rejection which results in a much simpler design for general classes of disturbances.

ISSN:0020-7179    

DOI:10.1080/00207179508921932

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Uncertainty tolerance and H∞attenuations are two important concerns in feedback control design. It is therefore important to develop effective methods to compute the trade-off between these two objectives. Using a quasiconvex optimization approach, this paper develops algorithms for two problems in this regard: (1) given the uncertainty size of the system, compute the minimum H∞norm bound of the closed loop system reachable by state feedback control; and (2) given the required maximum acceptable H∞norm bound of the closed loop system, compute the maximum uncertainty size which can be tolerated when state feedback control is applied. A numerical example is included to show the trade-off between uncertainty tolerance and H∞attenuations, and the effectiveness of the algorithms.

ISSN:0020-7179    

DOI:10.1080/00207179508921933

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Noise distribution arising in certain applications frequently deviates from the assumed gaussian model, often being characterized by heavier tails generating the outliers. Since, in the presence of outliers, the performance of a Kalman filter can be very poor, a statistical approach-named QQ-plot—is suggested to make the Kalman filter more robust. In addition, the first and the second-order moments of noise processes are estimated simultaneously with the system states, using the QQ-plot of the noise samples generated in the ‘robustified’ Kalman filter algorithm. Results of simulation demonstrating the robustness of the proposed state estimators are also included.

ISSN:0020-7179    

DOI:10.1080/00207179508921934

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

We propose an MPC algorithm with desirable stability and constraint-handling properties, yet which retains computational simplicity. The closed-loop stability and constraint-handling are achieved by formulating an infinite-horizon objective and then solving an equivalent finite-horizon problem. On-line computational requirements for multi-time-scale systems, are reduced substantially by techniques called ‘blocking’ and ‘condensation’. We show that the blocking and condensation techniques are conveniently applied after expressing the MPC objective and constraint equations in terms of wavelet bases.

ISSN:0020-7179    

DOI:10.1080/00207179508921935

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Robust polynomial-based optimal control is re-examined by comparing its similarity with a seemingly different control design technique, internal model control (IMC). As well as investigating the relationship between optimal control and robust control, the comparison highlights some shortcomings of the present approach to IMC design, provides insight into the choice of design parameters and makes a contribution towards the drawing together of the robust and adaptive LQG approaches to control system design.

ISSN:0020-7179    

DOI:10.1080/00207179508921936

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The basic theory of Hankel operators is developed over a planar domain Ω. Among the potential applications areH∞control when the closed-loop system is required to be analytic in a planar domain Ω rather than the right half-plane, and more selective model reduction methods when the signals passing through the system have limited bandwidth.

ISSN:0020-7179    

DOI:10.1080/00207179508921937

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A new method is presented for estimating regions of asymptotic stability for autonomous nonlinear systems. The method applies to systems that can be proven to be non-oscillatory, using a suitable Lyapunov technique. It is especially effective for second-order systems that possess several equilibrium states for which the regions of attraction must be found. The determination of the regions of asymptotic stability requires the explicit computation of a Lyapunov function and the determination by backward numerical integration of a limited number of trajectories. The obtained estimates are close approximations of the exact regions of asymptotic stability of the system's stable equilibria.

ISSN:0020-7179    

DOI:10.1080/00207179508921938

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor