Exact stability integration in network designs

• US 6,202,007 B1
• Filed: 02/19/1999
• Issued: 03/13/2001
• Est. Priority Date: 02/19/1999
• Status: Expired due to Fees

• Current Assignee: John A. Spicer
• Original Assignee: John A. Spicer
• Inventors: Spicer, John A.
• Primary Examiner(s): Nguyen, Tan
• Assistant Examiner(s): Tran, Dalena
• Application Number:
  US09/253,098
• Time in Patent Office: 753 Days
• Field of Search: 701/3, 701/4, 244/3.1, 244/3.23, 244/3.24, 244/92, 244/93, 244/164, 244/177, 280/1.21, 367/906
• US Class Current: 701/3
• CPC Class Codes: B64C 13/16 actuated automatically, e.g. responsive to gust detectors
• CPC Class Codes: G05B 13/048 using a predictor

Abstract

A self starting predictor corrector method of arbitrary order is disclosed that uses exact stability integration in network designs for application in systems optimizing control of aircraft through improved numerical techniques. Such method defines a self starting predictor corrector routine for a numerical solution of differential equations having a main process that computes derivatives of the states with a n-th order numerical solution for a n-th order differential equation. Moreover, such method configures an exact stability algorithm for generating a numerical integration of a high order of any type linear or nonlinear filter or network by constraining extraneous eigenvalues in the high order filter or network to be a definite value.

Claims

1. A self-starting predictor corrector method of arbitrary order using exact stability integration in network designs for application in systems optimizing control of aircraft through improved numerical techniques comprising:

Defining a self-starting predictor corrector routine for a numerical solution of differential equations having a main process that describes a multiplicity of states of motion and a subprocess that computes derivatives of the states with a n-th order numerical solution for a n-th order differential equation; and

Configuring an exact stability algorithm for generating a numerical integration of a high order of any type linear or nonlinear filter or network by constraining extraneous eigenvalues in the high order filter or network to be a definite value.

2. The self-starting predictor corrector method of arbitrary order of claim 1, wherein the n-th order numerical solution for the n-th order differential equation Y′

=f(y,t), Y(0)=f(y₀,t₀) has the form;

$Y_{n+1}=\underset{I=0}{\overset{N-1}{\sum <br><br>}}<br><br>\left(a_i<br><br>Y_{n-i}+{\mathrm{hb}}_i<br><br>Y_{n-i}^{\mathrm{\prime <br><br>}}\right).$

3. The self-starting predictor-corrector method of arbitrary order of claim 1, wherein a system of n equations is formed by configuring the equation $Y_{n+1}=\sum _{}^{}$

I=0N-1

(ai

Yn-i+hbi

Yn-i′

)

to be exactly correct for y=1t,t², . . . , tⁿ.

4. The self-starting predictor corrector method of arbitrary order of claim 1, wherein exact stability constraints are obtained by:

obtaining the Z transform of the transfer process $y<br><br>\left(z\right)/y^{\mathrm{\prime <br><br>}}<br><br>\left(z\right)=\frac{h(b_0<br><br>z^{-1}+b_1<br><br>z^{-2}+\mathrm{\dots <br><br>}+b_{n-1}<br><br>z^{-\left(n-1\right)}}{1.-\left(a_0<br><br>z^{-1}+a_1<br><br>z^{-2}+\mathrm{\dots <br><br>}+a_{n-1}<br><br>z^{-\left(n-1\right)}\right)};<br><br>$

considering $y<br><br>\left(z\right)/y^{\mathrm{\prime <br><br>}}<br><br>\left(z\right)=\frac{h(b_0<br><br>z^{-1}+b_1<br><br>z^{-2}+\mathrm{\dots <br><br>}+b_{n-1}<br><br>z^{-\left(n-1\right)}}{1.-(a_0<br><br>z^{-1}+a_1<br><br>z^{-2}+\mathrm{\dots <br><br>}+a_{n-1}<br><br>z^{-\left(n-1\right)}}$

as an open loop response;

designating ∂

f/∂

y_i by −

A_i; and

rearranging a closed loop for negative feedback to obtain the pulse response of an exact stability predictor given by $z^{-1}<br><br>\left\{\frac{{\left(b_0<br><br>A_0<br><br>Z^{n-1}+b_1<br><br>A_1<br><br>Z^{n-2}+\mathrm{\dots <br><br>}+A_{n-1}\right)}^h}{Z^n-\left(a_0-b_0<br><br>A_0^h\right)<br><br>Z^{n-1}+\mathrm{\dots <br><br>}+a_{n-1}-b_{n-1}<br><br>A_{n-1}^h)}\right\}.$

5. The self-starting predictor corrector method of arbitrary order of claim 1, wherein a subroutine computes the derivatives of the states being integrated by using a relationship from the formula Ae[k]=C[k]/(2*A[k]) between the coefficients and the zeros of an equation to yield the following equalities:

6. The self-starting predictor corrector method of arbitrary order of claim 1, wherein the corrector is initially assumed to be a first order method using only the initial value to obtain the next few values, then the order is updated to a second order, etc. until the desired order is reached.

7. The self-starting predictor corrector method of arbitrary order of claim 1, wherein the integration interval, due to truncation error of the one-step method, is decreased by a factor 2*PO-W(SF) in the self-starting routine so that the integration order and step size are increased in an stepwise manner until the desired values are obtained.