Chapter9.1:线性系统的状态空间分析与综合(下)

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Example 9.6

已知系统传递函数:

  1. G ( s ) = ( s − 1 ) ( s + 2 ) ( s + 1 ) ( s − 2 ) ( s + 3 ) G(s)=\displaystyle\frac{(s-1)(s+2)}{(s+1)(s-2)(s+3)} G(s)=(s+1)(s2)(s+3)(s1)(s+2)
  2. G ( s ) = 2 s 3 + s 2 + 7 s s 4 + 3 s 3 + 5 s 2 + 4 s G(s)=\displaystyle\frac{2s^3+s^2+7s}{s^4+3s^3+5s^2+4s} G(s)=s4+3s3+5s2+4s2s3+s2+7s
  3. G ( s ) = 3 s 3 + s 2 + s + 1 s 3 + 1 G(s)=\displaystyle\frac{3s^3+s^2+s+1}{s^3+1} G(s)=s3+13s3+s2+s+1
  4. G ( s ) = 1 ( s + 3 ) 3 G(s)=\displaystyle\frac{1}{(s+3)^3} G(s)=(s+3)31

写出系统可控标准型和可观测标准型最小实现。

解:

  1. G ( s ) = ( s − 1 ) ( s + 2 ) ( s + 1 ) ( s − 2 ) ( s + 3 ) G(s)=\displaystyle\frac{(s-1)(s+2)}{(s+1)(s-2)(s+3)} G(s)=(s+1)(s2)(s+3)(s1)(s+2)

    由于系统传递函数的分子、分母不存在零极点对消,故系统可控可观。

    由于
    G ( s ) = ( s − 1 ) ( s + 2 ) ( s + 1 ) ( s − 2 ) ( s + 3 ) = s 2 + s − 2 s 3 + 2 s 2 − 5 s − 6 G(s)=\displaystyle\frac{(s-1)(s+2)}{(s+1)(s-2)(s+3)}=\frac{s^2+s-2}{s^3+2s^2-5s-6} G(s)=(s+1)(s2)(s+3)(s1)(s+2)=s3+2s25s6s2+s2
    则系统可控标准型最小实现为:
    x ˙ c = [ 0 1 0 0 0 1 6 5 − 2 ] x c + [ 0 0 1 ] u , y = [ − 2 1 1 ] x c \dot{x}_c=\begin{bmatrix} 0 & 1 & 0\\ 0 & 0 & 1\\ 6 & 5 & -2 \end{bmatrix}x_c+\begin{bmatrix} 0\\0\\1 \end{bmatrix}u,y=\begin{bmatrix} -2 & 1 & 1 \end{bmatrix}x_c x˙c=006105012xc+001uy=[211]xc
    可观测标准型最小实现为可控标准型最小实现的对偶形式:
    x ˙ o = [ 0 0 6 1 0 5 0 1 − 2 ] x o + [ − 2 1 1 ] u , y = [ 0 0 1 ] x o \dot{x}_o=\begin{bmatrix} 0 & 0 & 6\\ 1 & 0 & 5\\ 0 & 1 & -2 \end{bmatrix}x_o+\begin{bmatrix} -2\\1\\1 \end{bmatrix}u,y=\begin{bmatrix} 0 & 0 & 1 \end{bmatrix}x_o x˙o=010001652xo+211uy=[001]xo

  2. G ( s ) = 2 s 3 + s 2 + 7 s s 4 + 3 s 3 + 5 s 2 + 4 s G(s)=\displaystyle\frac{2s^3+s^2+7s}{s^4+3s^3+5s^2+4s} G(s)=s4+3s3+5s2+4s2s3+s2+7s

    由于传递函数的分子、分母存在零极点对消,故系统不完全可控可观测,因此,最小实现的传递函数为:
    G ( s ) = 2 s 2 + s + 7 s 3 + 3 s 2 + 5 s + 4 G(s)=\frac{2s^2+s+7}{s^3+3s^2+5s+4} G(s)=s3+3s2+5s+42s2+s+7
    则系统的可控标准型最小实现为:
    x ˙ c = [ 0 1 0 0 0 1 − 4 − 5 − 3 ] x c + [ 0 0 1 ] u , y = [ 7 1 2 ] x c \dot{x}_c=\begin{bmatrix} 0 & 1 & 0\\ 0 & 0 & 1\\ -4 & -5 & -3 \end{bmatrix}x_c+\begin{bmatrix} 0\\0\\1 \end{bmatrix}u,y=\begin{bmatrix} 7 & 1 & 2 \end{bmatrix}x_c x˙c=004105013xc+001uy=[712]xc
    可观测标准型最小实现为可控标准型最小实现的对偶形式:
    x ˙ o = [ 0 0 − 4 1 0 − 5 0 1 − 3 ] x o + [ 7 1 2 ] u , y = [ 0 0 1 ] x o \dot{x}_o=\begin{bmatrix} 0 & 0 & -4\\ 1 & 0 & -5\\ 0 & 1 & -3 \end{bmatrix}x_o+\begin{bmatrix} 7\\ 1\\ 2 \end{bmatrix}u,y=\begin{bmatrix} 0 & 0 & 1 \end{bmatrix}x_o x˙o=010001453xo+712uy=[001]xo

  3. G ( s ) = 3 s 3 + s 2 + s + 1 s 3 + 1 G(s)=\displaystyle\frac{3s^3+s^2+s+1}{s^3+1} G(s)=s3+13s3+s2+s+1

    由于系统传递函数的分子、分母不存在零极点对消,故系统可控可观。

    由于
    G ( s ) = 3 + s 2 + s − 2 s 3 + 1 G(s)=3+\frac{s^2+s-2}{s^3+1} G(s)=3+s3+1s2+s2
    则系统的可控标准型最小实现为:
    x ˙ c = [ 0 1 0 0 0 1 − 1 0 0 ] x c + [ 0 0 1 ] u , y = [ − 2 1 1 ] x c + 3 u \dot{x}_c=\begin{bmatrix} 0 & 1 & 0\\ 0 & 0 & 1\\ -1 & 0 & 0 \end{bmatrix}x_c+\begin{bmatrix} 0\\0\\1 \end{bmatrix}u,y=\begin{bmatrix} -2 & 1 & 1 \end{bmatrix}x_c+3u x˙c=001100010xc+001uy=[211]xc+3u
    可观测标准型最小实现为可控标准型最小实现的对偶形式:
    x ˙ o = [ 0 0 − 1 1 0 0 0 1 0 ] x o + [ − 2 1 1 ] u , y = [ 0 0 1 ] x o + 3 u \dot{x}_o=\begin{bmatrix} 0 & 0 & -1\\ 1 & 0 & 0\\ 0 & 1 & 0 \end{bmatrix}x_o+\begin{bmatrix} -2\\ 1\\ 1 \end{bmatrix}u,y=\begin{bmatrix} 0 & 0 & 1 \end{bmatrix}x_o+3u x˙o=010001100xo+211uy=[001]xo+3u

  4. G ( s ) = 1 ( s + 3 ) 3 G(s)=\displaystyle\frac{1}{(s+3)^3} G(s)=(s+3)31

    由于系统传递函数的分子、分母不存在零极点对消,故系统可控可观。

    由于
    G ( s ) = 1 s 3 + 9 s 2 + 27 s + 27 G(s)=\frac{1}{s^3+9s^2+27s+27} G(s)=s3+9s2+27s+271
    则系统的可控标准型最小实现为:
    x ˙ c = [ 0 1 0 0 0 1 − 27 − 27 − 9 ] x c + [ 0 0 1 ] u , y = [ 1 0 0 ] x c \dot{x}_c=\begin{bmatrix} 0 & 1 & 0\\ 0 & 0 & 1\\ -27 & -27 & -9 \end{bmatrix}x_c+\begin{bmatrix} 0\\0\\1 \end{bmatrix}u,y=\begin{bmatrix} 1 & 0 & 0 \end{bmatrix}x_c x˙c=00271027019xc+001uy=[100]xc
    可观测标准型最小实现为可控标准型最小实现的对偶形式:
    x ˙ o = [ 0 0 − 27 1 0 − 27 0 1 − 9 ] x o + [ 1 0 0 ] u , y = [ 0 0 1 ] x o \dot{x}_o=\begin{bmatrix} 0 & 0 & -27\\ 1 & 0 & -27\\ 0 & 1 & -9 \end{bmatrix}x_o+\begin{bmatrix} 1\\0\\0 \end{bmatrix}u,y=\begin{bmatrix} 0 & 0 & 1 \end{bmatrix}x_o x˙o=01000127279xo+100uy=[001]xo

Example 9.7

已知系统的传递函数列向量:

  1. g ( s ) = [ 1 s + 1 1 s + 2 1 s + 3 ] T g(s)=\begin{bmatrix}\displaystyle\frac{1}{s+1} & \displaystyle\frac{1}{s+2} & \displaystyle\frac{1}{s+3}\end{bmatrix}^T g(s)=[s+11s+21s+31]T
  2. g ( s ) = [ 1 s s 2 − 1 1 s − 1 ] T g(s)=\begin{bmatrix}1 & \displaystyle\frac{s}{s^2-1} & \displaystyle\frac{1}{s-1}\end{bmatrix}^T g(s)=[1s21ss11]T
  3. g ( s ) = [ 1 s 0 − 1 s 2 + 1 ] T g(s)=\begin{bmatrix}\displaystyle\frac{1}{s} & 0 & \displaystyle\frac{-1}{s^2+1}\end{bmatrix}^T g(s)=[s10s2+11]T
  4. g ( s ) = [ 1 s 2 + 1 1 s 2 − 1 ] T g(s)=\begin{bmatrix}\displaystyle\frac{1}{s^2+1} & \displaystyle\frac{1}{s^2-1}\end{bmatrix}^T g(s)=[s2+11s211]T

求系统可控标准型实现。

解:

  1. g ( s ) = [ 1 s + 1 1 s + 2 1 s + 3 ] T g(s)=\begin{bmatrix}\displaystyle\frac{1}{s+1} & \displaystyle\frac{1}{s+2} & \displaystyle\frac{1}{s+3}\end{bmatrix}^T g(s)=[s+11s+21s+31]T

    引入中间变量 Z Z Z,使得:
    g ( s ) = Y ( s ) Z ( s ) Z ( s ) U ( s ) = 1 ( s + 1 ) ( s + 2 ) ( s + 3 ) [ ( s + 2 ) ( s + 3 ) ( s + 1 ) ( s + 3 ) ( s + 1 ) ( s + 2 ) ] = 1 s 3 + 6 s 2 + 11 s + 6 [ s 2 + 5 s + 6 s 2 + 4 s + 3 s 2 + 3 s + 2 ] \begin{aligned} g(s)&=\frac{Y(s)Z(s)}{Z(s)U(s)}=\frac{1}{(s+1)(s+2)(s+3)}\begin{bmatrix} (s+2)(s+3)\\ (s+1)(s+3)\\ (s+1)(s+2) \end{bmatrix}\\\\ &=\frac{1}{s^3+6s^2+11s+6}\begin{bmatrix} s^2+5s+6\\ s^2+4s+3\\ s^2+3s+2 \end{bmatrix} \end{aligned} g(s)=Z(s)U(s)Y(s)Z(s)=(s+1)(s+2)(s+3)1(s+2)(s+3)(s+1)(s+3)(s+1)(s+2)=s3+6s2+11s+61s2+5s+6s2+4s+3s2+3s+2

    Z ( s ) U ( s ) = 1 s 3 + 6 s 2 + 11 s + 6 , Y ( s ) Z ( s ) = [ s 2 + 5 s + 6 s 2 + 4 s + 3 s 2 + 3 s + 2 ] \frac{Z(s)}{U(s)}=\frac{1}{s^3+6s^2+11s+6},\frac{Y(s)}{Z(s)}=\begin{bmatrix} s^2+5s+6\\ s^2+4s+3\\ s^2+3s+2 \end{bmatrix} U(s)Z(s)=s3+6s2+11s+61Z(s)Y(s)=s2+5s+6s2+4s+3s2+3s+2
    选择 x 1 = z , x 2 = z ˙ , x 3 = z ¨ x_1=z,x_2=\dot{z},x_3=\ddot{z} x1=z,x2=z˙,x3=z¨,可得可控标准型实现为:
    x ˙ = [ 0 1 0 0 0 1 − 6 − 11 − 6 ] x + [ 0 0 1 ] u , y = [ 6 5 1 3 4 1 2 3 1 ] x \dot{x}=\begin{bmatrix} 0 & 1 & 0\\ 0 & 0 & 1\\ -6 & -11 & -6 \end{bmatrix}x+\begin{bmatrix} 0\\0\\1 \end{bmatrix}u,y=\begin{bmatrix} 6 & 5 & 1\\ 3 & 4 & 1\\ 2 & 3 & 1 \end{bmatrix}x x˙=0061011016x+001uy=632543111x

  2. g ( s ) = [ 1 s s 2 − 1 1 s − 1 ] T g(s)=\begin{bmatrix}1 & \displaystyle\frac{s}{s^2-1} & \displaystyle\frac{1}{s-1}\end{bmatrix}^T g(s)=[1s21ss11]T

    由于
    g ( s ) = [ 1 s s 2 − 1 1 s − 1 ] = 1 s 2 − 1 [ 0 s s + 1 ] + [ 1 0 0 ] g(s)=\begin{bmatrix} 1\\ \displaystyle\frac{s}{s^2-1}\\ \displaystyle\frac{1}{s-1} \end{bmatrix}=\displaystyle\frac{1}{s^2-1}\begin{bmatrix} 0\\ s\\ s+1 \end{bmatrix}+\begin{bmatrix} 1\\ 0\\ 0 \end{bmatrix} g(s)=1s21ss11=s2110ss+1+100
    利用传递函数直接分解法可得可控标准型实现为:
    x ˙ = [ 0 1 1 0 ] x + [ 0 1 ] u , y = [ 0 0 0 1 1 1 ] x + [ 1 0 0 ] u \dot{x}=\begin{bmatrix} 0 & 1\\ 1 & 0 \end{bmatrix}x+\begin{bmatrix} 0\\1 \end{bmatrix}u,y=\begin{bmatrix} 0 & 0\\ 0 & 1\\ 1 & 1 \end{bmatrix}x+\begin{bmatrix} 1\\0\\0 \end{bmatrix}u x˙=[0110]x+[01]uy=001011x+100u

  3. g ( s ) = [ 1 s 0 − 1 s 2 + 1 ] T g(s)=\begin{bmatrix}\displaystyle\frac{1}{s} & 0 & \displaystyle\frac{-1}{s^2+1}\end{bmatrix}^T g(s)=[s10s2+11]T

    由于
    g ( s ) = [ 1 s 0 − 1 s 2 + 1 ] = 1 s 3 + s [ s 2 + 1 0 − s ] g(s)=\begin{bmatrix} \displaystyle\frac{1}{s}\\ 0\\ \displaystyle\frac{-1}{s^2+1} \end{bmatrix}=\frac{1}{s^3+s}\begin{bmatrix} s^2+1\\ 0\\ -s \end{bmatrix} g(s)=s10s2+11=s3+s1s2+10s
    利用传递函数直接分解法可得可控标准型实现为:
    x ˙ = [ 0 1 0 0 0 1 0 − 1 0 ] x + [ 0 0 1 ] u , y = [ 1 0 1 0 0 0 0 − 1 0 ] x \dot{x}=\begin{bmatrix} 0 & 1 & 0\\ 0 & 0 & 1\\ 0 & -1 & 0 \end{bmatrix}x+\begin{bmatrix} 0\\ 0\\ 1 \end{bmatrix}u,y=\begin{bmatrix} 1 & 0 & 1\\ 0 & 0 & 0\\ 0 & -1 & 0 \end{bmatrix}x x˙=000101010x+001uy=100001100x

  4. g ( s ) = [ 1 s 2 + 1 1 s 2 − 1 ] T g(s)=\begin{bmatrix}\displaystyle\frac{1}{s^2+1} & \displaystyle\frac{1}{s^2-1}\end{bmatrix}^T g(s)=[s2+11s211]T

    由于
    g ( s ) = [ 1 s 2 + 1 1 s 2 − 1 ] = 1 s 4 − 1 [ s 2 − 1 s 2 + 1 ] g(s)=\begin{bmatrix} \displaystyle\frac{1}{s^2+1}\\ \displaystyle\frac{1}{s^2-1} \end{bmatrix}=\frac{1}{s^4-1}\begin{bmatrix} s^2-1\\ s^2+1 \end{bmatrix} g(s)=s2+11s211=s411[s21s2+1]
    利用传递函数直接分解法可得可控标准型实现为:
    x ˙ = [ 0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 0 ] x + [ 0 0 0 1 ] u , y = [ − 1 0 1 0 1 0 1 0 ] x \dot{x}=\begin{bmatrix} 0 & 1 & 0 & 0\\ 0 & 0 & 1 & 0\\ 0 & 0 & 0 & 1\\ 1 & 0 & 0 & 0 \end{bmatrix}x+\begin{bmatrix} 0\\ 0\\ 0\\ 1 \end{bmatrix}u,y=\begin{bmatrix} -1 & 0 & 1 & 0\\ 1 & 0 & 1 & 0 \end{bmatrix}x x˙=0001100001000010x+0001uy=[11001100]x

Example 9.8

已知系统的传递函数行向量:

  1. g ( s ) = [ 0 1 1 s + 1 1 s + 2 ] g(s)=\begin{bmatrix}0 & 1 & \displaystyle\frac{1}{s+1} & \displaystyle\frac{1}{s+2}\end{bmatrix} g(s)=[01s+11s+21]
  2. g ( s ) = [ 1 s + 1 1 s − 1 2 s s 2 − 1 ] g(s)=\begin{bmatrix}\displaystyle\frac{1}{s+1} & \displaystyle\frac{1}{s-1} & \displaystyle\frac{2s}{s^2-1}\end{bmatrix} g(s)=[s+11s11s212s]
  3. g ( s ) = [ 3 2 s 2 + 1 s 2 s 2 + 1 ] g(s)=\begin{bmatrix}3& \displaystyle\frac{2}{s^2+1} & \displaystyle\frac{s^2}{s^2+1}\end{bmatrix} g(s)=[3s2+12s2+1s2]

求系统可观测标准型实现。

解:

  1. g ( s ) = [ 0 1 1 s + 1 1 s + 2 ] g(s)=\begin{bmatrix}0 & 1 & \displaystyle\frac{1}{s+1} & \displaystyle\frac{1}{s+2}\end{bmatrix} g(s)=[01s+11s+21]

    由于
    g ( s ) = Y ( s ) U ( s ) = 1 ( s + 1 ) ( s + 2 ) [ 0 0 s + 2 s + 1 ] + [ 0 1 0 0 ] g(s)=\frac{Y(s)}{U(s)}=\frac{1}{(s+1)(s+2)}\begin{bmatrix} 0 & 0 & s+2 & s+1 \end{bmatrix}+\begin{bmatrix} 0 & 1 & 0 & 0 \end{bmatrix} g(s)=U(s)Y(s)=(s+1)(s+2)1[00s+2s+1]+[0100]
    此为四输入-单输出系统。由于线性系统满足叠加原理,故系统微分方程可写为:
    y ¨ + 3 y ˙ + 2 y = u ˙ 3 + 2 u 3 + u ˙ 4 + u 4 \ddot{y}+3\dot{y}+2y=\dot{u}_3+2u_3+\dot{u}_4+u_4 y¨+3y˙+2y=u˙3+2u3+u˙4+u4
    x 1 = y ˙ + 3 y − u 3 − u 4 , x 2 = y x_1=\dot{y}+3y-u_3-u_4,x_2=y x1=y˙+3yu3u4x2=y,则有
    { x ˙ 1 = − 2 x 2 + 2 u 3 + u 4 x ˙ 2 = x 1 − 3 x 2 + u 3 + u 4 y = x 2 \begin{cases} &\dot{x}_1=-2x_2+2u_3+u_4\\\\ &\dot{x}_2=x_1-3x_2+u_3+u_4\\\\ &y=x_2 \end{cases} x˙1=2x2+2u3+u4x˙2=x13x2+u3+u4y=x2
    即系统可观测标准型实现的向量-矩阵形式为:
    x ˙ = [ 0 − 2 1 − 3 ] x + [ 0 0 2 1 0 0 1 1 ] u , y = [ 0 1 ] x + [ 0 1 0 0 ] u \dot{x}=\begin{bmatrix} 0 & -2\\ 1 & -3 \end{bmatrix}x+\begin{bmatrix} 0 & 0 & 2 & 1\\ 0 & 0 & 1 & 1 \end{bmatrix}u,y=\begin{bmatrix} 0 & 1 \end{bmatrix}x+\begin{bmatrix} 0 & 1 & 0 & 0 \end{bmatrix}u x˙=[0123]x+[00002111]uy=[01]x+[0100]u

  2. g ( s ) = [ 1 s + 1 1 s − 1 2 s s 2 − 1 ] g(s)=\begin{bmatrix}\displaystyle\frac{1}{s+1} & \displaystyle\frac{1}{s-1} & \displaystyle\frac{2s}{s^2-1}\end{bmatrix} g(s)=[s+11s11s212s]

    系统的传递函数向量:
    g ( s ) = Y ( s ) U ( s ) = 1 s 2 − 1 [ s − 1 s 2 + s 2 s ] g(s)=\frac{Y(s)}{U(s)}=\frac{1}{s^2-1}\begin{bmatrix} s-1 & s^2+s & 2s \end{bmatrix} g(s)=U(s)Y(s)=s211[s1s2+s2s]
    此为三输入-单输出系统。由于线性系统满足叠加原理,故系统微分方程可写为:
    y ¨ − y = u ˙ 1 − u 1 + u ¨ 2 + u ˙ 2 + 2 u ˙ 3 \ddot{y}-y=\dot{u}_1-u_1+\ddot{u}_2+\dot{u}_2+2\dot{u}_3 y¨y=u˙1u1+u¨2+u˙2+2u˙3
    x 1 = y ˙ − u 1 − u ˙ 2 − u 2 − 2 u 3 , x 2 = y − u 2 x_1=\dot{y}-u_1-\dot{u}_2-u_2-2u_3,x_2=y-u_2 x1=y˙u1u˙2u22u3x2=yu2,则有:
    { x ˙ 1 = x 2 − u 1 + u 2 x ˙ 2 = x 1 + u 1 + u 2 + 2 u 3 y = x 2 + u 2 \begin{cases} &\dot{x}_1=x_2-u_1+u_2\\\\ &\dot{x}_2=x_1+u_1+u_2+2u_3\\\\ &y=x_2+u_2 \end{cases} x˙1=x2u1+u2x˙2=x1+u1+u2+2u3y=x2+u2
    即系统可观测标准型实现的向量-矩阵形式为:
    x ˙ = [ 0 1 1 0 ] x + [ − 1 1 0 1 1 2 ] u , y = [ 0 1 ] x + [ 0 1 0 ] u \dot{x}=\begin{bmatrix} 0 & 1\\ 1 & 0 \end{bmatrix}x+\begin{bmatrix} -1 & 1 & 0\\ 1 & 1 & 2 \end{bmatrix}u,y=\begin{bmatrix} 0 & 1 \end{bmatrix}x+\begin{bmatrix} 0 & 1 & 0 \end{bmatrix}u x˙=[0110]x+[111102]uy=[01]x+[010]u

  3. g ( s ) = [ 3 2 s 2 + 1 s 2 s 2 + 1 ] g(s)=\begin{bmatrix}3& \displaystyle\frac{2}{s^2+1} & \displaystyle\frac{s^2}{s^2+1}\end{bmatrix} g(s)=[3s2+12s2+1s2]

    系统的传递函数向量:
    g ( s ) = Y ( s ) U ( s ) = 1 s 2 + 1 [ 3 s 2 + 3 2 s 2 ] g(s)=\frac{Y(s)}{U(s)}=\frac{1}{s^2+1}\begin{bmatrix} 3s^2+3 & 2 & s^2 \end{bmatrix} g(s)=U(s)Y(s)=s2+11[3s2+32s2]
    此为三输入-单输出系统。由于线性系统满足叠加原理,故系统微分方程可写为:
    y ¨ + y = 3 u ¨ 1 + 3 u 1 + 2 u 2 + u ¨ 3 \ddot{y}+y=3\ddot{u}_1+3u_1+2u_2+\ddot{u}_3 y¨+y=3u¨1+3u1+2u2+u¨3
    x 1 = y ˙ − 3 u ˙ 1 − u ˙ 3 , x 2 = y − 3 u 1 − u 3 x_1=\dot{y}-3\dot{u}_1-\dot{u}_3,x_2=y-3u_1-u_3 x1=y˙3u˙1u˙3x2=y3u1u3,则有:
    { x ˙ 1 = − x 2 + 2 u 2 − u 3 x ˙ 2 = x 1 y = x 2 + 3 u 1 + u 3 \begin{cases} &\dot{x}_1=-x_2+2u_2-u_3\\\\ &\dot{x}_2=x_1\\\\ &y=x_2+3u_1+u_3 \end{cases} x˙1=x2+2u2u3x˙2=x1y=x2+3u1+u3
    即系统可观测标准型实现的向量-矩阵形式为:
    x ˙ = [ 0 − 1 1 0 ] x + [ 0 2 − 1 0 0 0 ] u , y = [ 0 1 ] x + [ 3 0 1 ] u \dot{x}=\begin{bmatrix} 0 & -1\\ 1 & 0 \end{bmatrix}x+\begin{bmatrix} 0 & 2 & -1\\ 0 & 0 & 0 \end{bmatrix}u,y=\begin{bmatrix} 0 & 1 \end{bmatrix}x+\begin{bmatrix} 3 & 0 & 1 \end{bmatrix}u x˙=[0110]x+[002010]uy=[01]x+[301]u

Example 9.9

已知系统传递函数:

  1. G ( s ) = s 2 + s − 6 s 4 + 10 s 3 + 35 s 2 + 50 s + 24 G(s)=\displaystyle\frac{s^2+s-6}{s^4+10s^3+35s^2+50s+24} G(s)=s4+10s3+35s2+50s+24s2+s6
  2. G ( s ) = 4 s 2 + 17 s + 16 s 3 + 7 s 2 + 16 s + 12 G(s)=\displaystyle\frac{4s^2+17s+16}{s^3+7s^2+16s+12} G(s)=s3+7s2+16s+124s2+17s+16
  3. G ( s ) = 2 s 2 + 5 s + 1 s 3 + 6 s 2 + 12 s + 8 G(s)=\displaystyle\frac{2s^2+5s+1}{s^3+6s^2+12s+8} G(s)=s3+6s2+12s+82s2+5s+1
  4. G ( s ) = ( s + 1 ) 3 s 3 G(s)=\displaystyle\frac{(s+1)^3}{s^3} G(s)=s3(s+1)3

求系统的约当标准型或对角线标准型实现。

解:

  1. G ( s ) = s 2 + s − 6 s 4 + 10 s 3 + 35 s 2 + 50 s + 24 G(s)=\displaystyle\frac{s^2+s-6}{s^4+10s^3+35s^2+50s+24} G(s)=s4+10s3+35s2+50s+24s2+s6

    将系统传递函数分解为部分分式形式:
    G ( s ) = Y ( s ) U ( s ) = ( s + 3 ) ( s − 2 ) ( s + 1 ) ( s + 2 ) ( s + 3 ) ( s + 4 ) = − 1 s + 1 + 2 s + 2 + − 1 s + 4 G(s)=\frac{Y(s)}{U(s)}=\frac{(s+3)(s-2)}{(s+1)(s+2)(s+3)(s+4)}=\frac{-1}{s+1}+\frac{2}{s+2}+\frac{-1}{s+4} G(s)=U(s)Y(s)=(s+1)(s+2)(s+3)(s+4)(s+3)(s2)=s+11+s+22+s+41

    { X 1 ( s ) = 1 s + 1 U ( s ) X 2 ( s ) = 1 s + 2 U ( s ) X 3 ( s ) = 1 s + 4 U ( s ) \begin{cases} &X_1(s)=\displaystyle\frac{1}{s+1}U(s)\\\\ &X_2(s)=\displaystyle\frac{1}{s+2}U(s)\\\\ &X_3(s)=\displaystyle\frac{1}{s+4}U(s) \end{cases} X1(s)=s+11U(s)X2(s)=s+21U(s)X3(s)=s+41U(s)

    { x ˙ 1 = − x 1 + u x ˙ 2 = − 2 x 2 + u x ˙ 3 = − 4 x 3 + u \begin{cases} &\dot{x}_1=-x_1+u\\\\ &\dot{x}_2=-2x_2+u\\\\ &\dot{x}_3=-4x_3+u \end{cases} x˙1=x1+ux˙2=2x2+ux˙3=4x3+u
    向量-矩阵形式,可得系统对角线标准型最小实现为:
    x ˙ = [ − 1 0 0 0 − 2 0 0 0 − 4 ] x + [ 1 1 1 ] u , y = [ − 1 2 − 1 ] x \dot{x}=\begin{bmatrix} -1 & 0 & 0\\ 0 & -2 & 0\\ 0 & 0 & -4 \end{bmatrix}x+\begin{bmatrix} 1\\ 1\\ 1 \end{bmatrix}u,y=\begin{bmatrix} -1 & 2 & -1 \end{bmatrix}x x˙=100020004x+111uy=[121]x

  2. G ( s ) = 4 s 2 + 17 s + 16 s 3 + 7 s 2 + 16 s + 12 G(s)=\displaystyle\frac{4s^2+17s+16}{s^3+7s^2+16s+12} G(s)=s3+7s2+16s+124s2+17s+16

    将系统传递函数分解为部分分式形式:
    G ( s ) = Y ( s ) U ( s ) = 4 s 2 + 17 s + 16 ( s + 3 ) ( s + 2 ) 2 = − 2 ( s + 2 ) 2 + 3 s + 2 + 1 s + 3 G(s)=\frac{Y(s)}{U(s)}=\frac{4s^2+17s+16}{(s+3)(s+2)^2}=\frac{-2}{(s+2)^2}+\frac{3}{s+2}+\frac{1}{s+3} G(s)=U(s)Y(s)=(s+3)(s+2)24s2+17s+16=(s+2)22+s+23+s+31

    { X 1 ( s ) = 1 ( s + 2 ) 2 U ( s ) = 1 s + 2 X 2 ( s ) X 2 ( s ) = 1 s + 2 U ( s ) X 3 ( s ) = 1 s + 3 U ( s ) \begin{cases} &X_1(s)=\displaystyle\frac{1}{(s+2)^2}U(s)=\displaystyle\frac{1}{s+2}X_2(s)\\\\ &X_2(s)=\displaystyle\frac{1}{s+2}U(s)\\\\ &X_3(s)=\displaystyle\frac{1}{s+3}U(s) \end{cases} X1(s)=(s+2)21U(s)=s+21X2(s)X2(s)=s+21U(s)X3(s)=s+31U(s)

    { x ˙ 1 = − 2 x 1 + x 2 x ˙ 2 = − 2 x 2 + u x ˙ 3 = − 3 x 3 + u \begin{cases} &\dot{x}_1=-2x_1+x_2\\\\ &\dot{x}_2=-2x_2+u\\\\ &\dot{x}_3=-3x_3+u \end{cases} x˙1=2x1+x2x˙2=2x2+ux˙3=3x3+u
    向量-矩阵形式,可得系统约当标准型实现为:
    x ˙ = [ − 2 1 0 0 − 2 0 0 0 − 3 ] x + [ 0 1 1 ] u , y = [ − 2 3 1 ] x \dot{x}=\begin{bmatrix} -2 & 1 & 0\\ 0 & -2 & 0\\ 0 & 0 & -3 \end{bmatrix}x+\begin{bmatrix} 0\\ 1\\ 1 \end{bmatrix}u,y=\begin{bmatrix} -2 & 3 & 1 \end{bmatrix}x x˙=200120003x+011uy=[231]x

  3. G ( s ) = 2 s 2 + 5 s + 1 s 3 + 6 s 2 + 12 s + 8 G(s)=\displaystyle\frac{2s^2+5s+1}{s^3+6s^2+12s+8} G(s)=s3+6s2+12s+82s2+5s+1

    将系统传递函数分解为部分分式形式:
    G ( s ) = Y ( s ) U ( s ) = 2 s 2 + 5 s + 1 ( s + 2 ) 3 = − 1 ( s + 2 ) 3 + − 3 ( s + 2 ) 2 + 2 s + 2 G(s)=\frac{Y(s)}{U(s)}=\frac{2s^2+5s+1}{(s+2)^3}=\frac{-1}{(s+2)^3}+\frac{-3}{(s+2)^2}+\frac{2}{s+2} G(s)=U(s)Y(s)=(s+2)32s2+5s+1=(s+2)31+(s+2)23+s+22

    { X 1 ( s ) = 1 ( s + 2 ) 3 U ( s ) = 1 s + 2 X 2 ( s ) X 2 ( s ) = 1 ( s + 2 ) 2 U ( s ) = 1 s + 2 X 3 ( s ) X 3 ( s ) = 1 s + 2 U ( s ) \begin{cases} &X_1(s)=\displaystyle\frac{1}{(s+2)^3}U(s)=\frac{1}{s+2}X_2(s)\\\\ &X_2(s)=\displaystyle\frac{1}{(s+2)^2}U(s)=\frac{1}{s+2}X_3(s)\\\\ &X_3(s)=\displaystyle\frac{1}{s+2}U(s) \end{cases} X1(s)=(s+2)31U(s)=s+21X2(s)X2(s)=(s+2)21U(s)=s+21X3(s)X3(s)=s+21U(s)

    { x ˙ 1 = − 2 x 1 + x 2 x ˙ 2 = − 2 x 2 + x 3 x ˙ 3 = − 2 x 3 + u \begin{cases} &\dot{x}_1=-2x_1+x_2\\\\ &\dot{x}_2=-2x_2+x_3\\\\ &\dot{x}_3=-2x_3+u \end{cases} x˙1=2x1+x2x˙2=2x2+x3x˙3=2x3+u
    向量-矩阵形式,可得系统的约当标准型实现为:
    x ˙ = [ − 2 1 0 0 − 2 1 0 0 − 2 ] x + [ 0 0 1 ] u , y = [ − 1 − 3 2 ] x \dot{x}=\begin{bmatrix} -2 & 1 & 0\\ 0 & -2 & 1\\ 0 & 0 & -2 \end{bmatrix}x+\begin{bmatrix} 0\\ 0\\ 1 \end{bmatrix}u,y=\begin{bmatrix} -1 & -3 & 2 \end{bmatrix}x x˙=200120012x+001uy=[132]x

  4. G ( s ) = ( s + 1 ) 3 s 3 G(s)=\displaystyle\frac{(s+1)^3}{s^3} G(s)=s3(s+1)3

    将系统的传递函数分解为部分分式形式:
    G ( s ) = Y ( s ) U ( s ) = ( s + 1 ) 3 s 3 = 1 + 3 s 2 + 3 s + 1 s 3 = 1 + 1 s 3 + 3 s 2 + 3 s G(s)=\frac{Y(s)}{U(s)}=\frac{(s+1)^3}{s^3}=1+\frac{3s^2+3s+1}{s^3}=1+\frac{1}{s^3}+\frac{3}{s^2}+\frac{3}{s} G(s)=U(s)Y(s)=s3(s+1)3=1+s33s2+3s+1=1+s31+s23+s3

    { X 1 ( s ) = 1 s 3 U ( s ) = 1 s X 2 ( s ) X 2 ( s ) = 1 s 2 U ( s ) = 1 s X 3 ( s ) X 3 ( s ) = 1 s U ( s ) \begin{cases} &X_1(s)=\displaystyle\frac{1}{s^3}U(s)=\frac{1}{s}X_2(s)\\\\ &X_2(s)=\displaystyle\frac{1}{s^2}U(s)=\frac{1}{s}X_3(s)\\\\ &X_3(s)=\displaystyle\frac{1}{s}U(s) \end{cases} X1(s)=s31U(s)=s1X2(s)X2(s)=s21U(s)=s1X3(s)X3(s)=s1U(s)

    { x ˙ 1 = x 2 x ˙ 2 = x 3 x ˙ 3 = u \begin{cases} &\dot{x}_1=x_2\\\\ &\dot{x}_2=x_3\\\\ &\dot{x}_3=u \end{cases} x˙1=x2x˙2=x3x˙3=u
    向量-矩阵形式,可得系统的约当标准型实现为:
    x ˙ = [ 0 1 0 0 0 1 0 0 0 ] x + [ 0 0 1 ] u , y = [ 1 3 3 ] x + u \dot{x}=\begin{bmatrix} 0 & 1 & 0\\ 0 & 0 & 1\\ 0 & 0 & 0 \end{bmatrix}x+\begin{bmatrix} 0\\ 0\\ 1 \end{bmatrix}u,y=\begin{bmatrix} 1 & 3 & 3 \end{bmatrix}x+u x˙=000100010x+001uy=[133]x+u

Example 9.10

已知系统状态矩阵为: A = [ 0 1 0 0 0 1 2 3 0 ] A=\begin{bmatrix}0&1&0\\0&0&1\\2&3&0\end{bmatrix} A=002103010,用下列方法求系统的状态转移矩阵 Φ ( t ) \Phi(t) Φ(t)

  1. 拉普拉斯变换法;
  2. 线性变换法;
  3. 凯莱-哈密顿定理(待定系数法);

解:

  1. 拉普拉斯变换法;

    因为
    ( s I − A ) − 1 = [ s − 1 0 0 s − 1 − 2 − 3 s ] − 1 = 1 ( s + 1 ) 2 ( s − 2 ) [ s 2 − 3 s 1 − 2 s 2 s 2 s − 3 s − 2 s 2 ] (sI-A)^{-1}=\begin{bmatrix} s & -1 & 0\\ 0 & s & -1\\ -2 & -3 & s \end{bmatrix}^{-1}=\frac{1}{(s+1)^2(s-2)}\begin{bmatrix} s^2-3 & s & 1\\ -2 & s^2 & s\\ 2s & -3s-2 & s^2 \end{bmatrix} (sIA)1=s021s301s1=(s+1)2(s2)1s2322sss23s21ss2
    所以
    Φ ( t ) = L − 1 [ ( s I − A ) − 1 ] = 1 9 [ ( 8 − 6 t ) e − t + e 2 t ( − 2 + 3 t ) e − t + 2 e 2 t − ( 1 + 3 t ) e − t + e 2 t − ( 2 + 6 t ) e − t + 2 e 2 t ( 5 − 3 t ) e − t + 4 e 2 t ( − 2 + 3 t ) e − t + 2 e 2 t ( − 4 + 6 t ) e − t + 4 e 2 t ( − 8 + 3 t ) e − t + 8 e 2 t ( 5 − 3 t ) e − t + 4 e 2 t ] \begin{aligned} \Phi(t)&=L^{-1}[(sI-A)^{-1}]\\\\ &=\frac{1}{9}\begin{bmatrix} (8-6t){\rm e}^{-t}+{\rm e}^{2t} & (-2+3t){\rm e}^{-t}+2{\rm e}^{2t} & -(1+3t){\rm e}^{-t}+{\rm e}^{2t}\\\\ -(2+6t){\rm e}^{-t}+2{\rm e}^{2t} & (5-3t){\rm e}^{-t}+4{\rm e}^{2t} & (-2+3t){\rm e}^{-t}+2{\rm e}^{2t}\\\\ (-4+6t){\rm e}^{-t}+4{\rm e}^{2t} & (-8+3t){\rm e}^{-t}+8{\rm e}^{2t} & (5-3t){\rm e}^{-t}+4{\rm e}^{2t} \end{bmatrix} \end{aligned} Φ(t)=L1[(sIA)1]=91(86t)et+e2t(2+6t)et+2e2t(4+6t)et+4e2t(2+3t)et+2e2t(53t)et+4e2t(8+3t)et+8e2t(1+3t)et+e2t(2+3t)et+2e2t(53t)et+4e2t

  2. 线性变换法;

    由于 A A A为友矩阵,故系统特征多项式为:
    f ( λ ) = λ 3 − 3 λ − 2 = ( λ + 1 ) 2 ( λ − 2 ) f(\lambda)=\lambda^3-3\lambda-2=(\lambda+1)^2(\lambda-2) f(λ)=λ33λ2=(λ+1)2(λ2)
    解得特征根为:
    λ 1 = λ 2 = − 1 , λ 3 = 2 \lambda_1=\lambda_2=-1,\lambda_3=2 λ1=λ2=1λ3=2
    因此:
    P = [ 1 0 1 λ 1 1 λ 3 λ 1 2 2 λ 1 λ 3 2 ] = [ 1 0 1 − 1 1 2 1 − 2 4 ] , P − 1 = 1 9 [ 8 − 2 − 1 6 3 − 3 1 2 1 ] Λ = P − 1 A P = [ − 1 1 0 0 − 1 0 0 0 2 ] , e A t = [ e − t t e − t 0 0 e − t 0 0 0 e 2 t ] \begin{aligned} &P=\begin{bmatrix} 1 & 0 & 1\\ \lambda_1 & 1 &\lambda_3\\ \lambda_1^2 & 2\lambda_1 & \lambda_3^2 \end{bmatrix}=\begin{bmatrix} 1 & 0 & 1\\ -1 & 1 & 2\\ 1 & -2 & 4 \end{bmatrix},P^{-1}=\frac{1}{9}\begin{bmatrix} 8 & -2 & -1\\ 6 & 3 & -3\\ 1 & 2 & 1 \end{bmatrix}\\\\ &\Lambda=P^{-1}AP=\begin{bmatrix} -1 & 1 & 0\\ 0 & -1 & 0\\ 0 & 0 & 2 \end{bmatrix},{\rm e}^{At}=\begin{bmatrix} {\rm e}^{-t} & t{\rm e}^{-t} & 0\\ 0 & {\rm e}^{-t} & 0\\ 0 & 0 & {\rm e}^{2t} \end{bmatrix} \end{aligned} P=1λ1λ12012λ11λ3λ32=111012124P1=91861232131Λ=P1AP=100110002eAt=et00tetet000e2t
    从而可得系统的状态转移矩阵为:
    Φ ( t ) = P e Λ t P − 1 = 1 9 [ ( 8 − 6 t ) e − t + e 2 t ( − 2 + 3 t ) e − t + 2 e 2 t − ( 1 + 3 t ) e − t + e 2 t − ( 2 + 6 t ) e − t + 2 e 2 t ( 5 − 3 t ) e − t + 4 e 2 t ( − 2 + 3 t ) e − t + 2 e 2 t ( − 4 + 6 t ) e − t + 4 e 2 t ( − 8 + 3 t ) e − t + 8 e 2 t ( 5 − 3 t ) e − t + 4 e 2 t ] \begin{aligned} \Phi(t)&=P{\rm e}^{\Lambda{t}}P^{-1}\\\\ &=\frac{1}{9}\begin{bmatrix} (8-6t){\rm e}^{-t}+{\rm e}^{2t} & (-2+3t){\rm e}^{-t}+2{\rm e}^{2t} & -(1+3t){\rm e}^{-t}+{\rm e}^{2t}\\\\ -(2+6t){\rm e}^{-t}+2{\rm e}^{2t} & (5-3t){\rm e}^{-t}+4{\rm e}^{2t} & (-2+3t){\rm e}^{-t}+2{\rm e}^{2t}\\\\ (-4+6t){\rm e}^{-t}+4{\rm e}^{2t} & (-8+3t){\rm e}^{-t}+8{\rm e}^{2t} & (5-3t){\rm e}^{-t}+4{\rm e}^{2t} \end{bmatrix} \end{aligned} Φ(t)=PeΛtP1=91(86t)et+e2t(2+6t)et+2e2t(4+6t)et+4e2t(2+3t)et+2e2t(53t)et+4e2t(8+3t)et+8e2t(1+3t)et+e2t(2+3t)et+2e2t(53t)et+4e2t

  3. 凯莱-哈密顿定理(待定系数法);

    根据凯莱-哈密顿定理可知:
    e A t = ∑ k = 0 n − 1 α k ( t ) A k = α 0 ( t ) I + α 1 ( t ) A + α 2 ( t ) A 2 {\rm e}^{At}=\sum_{k=0}^{n-1}\alpha_k(t)A^k=\alpha_0(t)I+\alpha_1(t)A+\alpha_2(t)A^2 eAt=k=0n1αk(t)Ak=α0(t)I+α1(t)A+α2(t)A2
    由于 A A A的特征值为: λ 1 = λ 2 = − 1 , λ 3 = 2 \lambda_1=\lambda_2=-1,\lambda_3=2 λ1=λ2=1λ3=2,因此:
    [ α 0 ( t ) α 1 ( t ) α 2 ( t ) ] = [ 1 λ 1 λ 1 2 0 1 2 λ 1 1 λ 3 λ 3 2 ] − 1 [ e λ 1 t t e λ 1 t e λ 3 t ] = [ 1 − 1 1 0 1 − 2 1 2 4 ] − 1 [ e λ 1 t t e λ 1 t e λ 3 t ] = 1 9 [ e − t + 6 t e − t + e 2 t − 2 e − t + 3 t e − t + 2 e 2 t − e − t − 3 t e − t + e 2 t ] \begin{bmatrix} \alpha_0(t)\\ \alpha_1(t)\\ \alpha_2(t) \end{bmatrix}=\begin{bmatrix} 1 & \lambda_1 & \lambda_1^2\\ 0 & 1 & 2\lambda_1\\ 1 & \lambda_3 & \lambda_3^2 \end{bmatrix}^{-1}\begin{bmatrix} {\rm e}^{\lambda_1t}\\ t{\rm e}^{\lambda_1t}\\ {\rm e}^{\lambda_3t} \end{bmatrix}=\begin{bmatrix} 1 & -1 & 1\\ 0 & 1 & -2\\ 1 & 2 & 4 \end{bmatrix}^{-1}\begin{bmatrix} {\rm e}^{\lambda_1t}\\ t{\rm e}^{\lambda_1t}\\ {\rm e}^{\lambda_3t} \end{bmatrix}=\frac{1}{9}\begin{bmatrix} {\rm e}^{-t}+6t{\rm e}^{-t}+{\rm e}^{2t}\\ -2{\rm e}^{-t}+3t{\rm e}^{-t}+2{\rm e}^{2t}\\ -{\rm e}^{-t}-3t{\rm e}^{-t}+{\rm e}^{2t} \end{bmatrix} α0(t)α1(t)α2(t)=101λ11λ3λ122λ1λ321eλ1tteλ1teλ3t=1011121241eλ1tteλ1teλ3t=91et+6tet+e2t2et+3tet+2e2tet3tet+e2t
    将上式代入可得:
    Φ ( t ) = α 0 ( t ) I + α 1 A + α 2 A 2 = 1 9 [ ( 8 − 6 t ) e − t + e 2 t ( − 2 + 3 t ) e − t + 2 e 2 t − ( 1 + 3 t ) e − t + e 2 t − ( 2 + 6 t ) e − t + 2 e 2 t ( 5 − 3 t ) e − t + 4 e 2 t ( − 2 + 3 t ) e − t + 2 e 2 t ( − 4 + 6 t ) e − t + 4 e 2 t ( − 8 + 3 t ) e − t + 8 e 2 t ( 5 − 3 t ) e − t + 4 e 2 t ] \begin{aligned} \Phi(t)&=\alpha_0(t)I+\alpha_1A+\alpha_2A^2\\\\ &=\frac{1}{9}\begin{bmatrix} (8-6t){\rm e}^{-t}+{\rm e}^{2t} & (-2+3t){\rm e}^{-t}+2{\rm e}^{2t} & -(1+3t){\rm e}^{-t}+{\rm e}^{2t}\\\\ -(2+6t){\rm e}^{-t}+2{\rm e}^{2t} & (5-3t){\rm e}^{-t}+4{\rm e}^{2t} & (-2+3t){\rm e}^{-t}+2{\rm e}^{2t}\\\\ (-4+6t){\rm e}^{-t}+4{\rm e}^{2t} & (-8+3t){\rm e}^{-t}+8{\rm e}^{2t} & (5-3t){\rm e}^{-t}+4{\rm e}^{2t} \end{bmatrix} \end{aligned} Φ(t)=α0(t)I+α1A+α2A2=91(86t)et+e2t(2+6t)et+2e2t(4+6t)et+4e2t(2+3t)et+2e2t(53t)et+4e2t(8+3t)et+8e2t(1+3t)et+e2t(2+3t)et+2e2t(53t)et+4e2t

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