Show that if a linear dynamical equation is controllable at $t_0$, then it is controllable at any $t<t_0$.











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Consider a $n$-dimentional $p$-input equation:
$$dot{x}=Ax+Bu$$
where $A$ and $B$ are constant $ntimes n$ and $ntimes p$ real matrices.



By definition, the latter state equation is said to be controllable if for any initial state $x(0)=x_0$ and any final state $x_1$, there exists an input that transfers $x_0$ to $x_1$ in a finite time.



Then, how can I show that if a linear dynamical equation is controllable at $t_0$ then it is controllable at any $t<t_0$?










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  • Do you mean a linear time invariant system, because general linear systems also include linear time variant systems?
    – Kwin van der Veen
    Nov 22 at 0:20










  • yeah linear time invariant system
    – Ali G
    Nov 22 at 3:54










  • Without loss of gbenerality, you can show if the terminal state $x_1=0$ at time $t_0$, then $x(t)=0$ for all $t>t_0$ .
    – Gustave
    Nov 23 at 14:39










  • What have you done? Perhaps it would be useful to find the solution of the system for $x$. Can you write down this formula?
    – SZN
    Nov 27 at 3:37















up vote
1
down vote

favorite












Consider a $n$-dimentional $p$-input equation:
$$dot{x}=Ax+Bu$$
where $A$ and $B$ are constant $ntimes n$ and $ntimes p$ real matrices.



By definition, the latter state equation is said to be controllable if for any initial state $x(0)=x_0$ and any final state $x_1$, there exists an input that transfers $x_0$ to $x_1$ in a finite time.



Then, how can I show that if a linear dynamical equation is controllable at $t_0$ then it is controllable at any $t<t_0$?










share|cite|improve this question
























  • Do you mean a linear time invariant system, because general linear systems also include linear time variant systems?
    – Kwin van der Veen
    Nov 22 at 0:20










  • yeah linear time invariant system
    – Ali G
    Nov 22 at 3:54










  • Without loss of gbenerality, you can show if the terminal state $x_1=0$ at time $t_0$, then $x(t)=0$ for all $t>t_0$ .
    – Gustave
    Nov 23 at 14:39










  • What have you done? Perhaps it would be useful to find the solution of the system for $x$. Can you write down this formula?
    – SZN
    Nov 27 at 3:37













up vote
1
down vote

favorite









up vote
1
down vote

favorite











Consider a $n$-dimentional $p$-input equation:
$$dot{x}=Ax+Bu$$
where $A$ and $B$ are constant $ntimes n$ and $ntimes p$ real matrices.



By definition, the latter state equation is said to be controllable if for any initial state $x(0)=x_0$ and any final state $x_1$, there exists an input that transfers $x_0$ to $x_1$ in a finite time.



Then, how can I show that if a linear dynamical equation is controllable at $t_0$ then it is controllable at any $t<t_0$?










share|cite|improve this question















Consider a $n$-dimentional $p$-input equation:
$$dot{x}=Ax+Bu$$
where $A$ and $B$ are constant $ntimes n$ and $ntimes p$ real matrices.



By definition, the latter state equation is said to be controllable if for any initial state $x(0)=x_0$ and any final state $x_1$, there exists an input that transfers $x_0$ to $x_1$ in a finite time.



Then, how can I show that if a linear dynamical equation is controllable at $t_0$ then it is controllable at any $t<t_0$?







control-theory linear-control






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edited Nov 27 at 3:35









SZN

2,713720




2,713720










asked Nov 21 at 23:08









Ali G

113




113












  • Do you mean a linear time invariant system, because general linear systems also include linear time variant systems?
    – Kwin van der Veen
    Nov 22 at 0:20










  • yeah linear time invariant system
    – Ali G
    Nov 22 at 3:54










  • Without loss of gbenerality, you can show if the terminal state $x_1=0$ at time $t_0$, then $x(t)=0$ for all $t>t_0$ .
    – Gustave
    Nov 23 at 14:39










  • What have you done? Perhaps it would be useful to find the solution of the system for $x$. Can you write down this formula?
    – SZN
    Nov 27 at 3:37


















  • Do you mean a linear time invariant system, because general linear systems also include linear time variant systems?
    – Kwin van der Veen
    Nov 22 at 0:20










  • yeah linear time invariant system
    – Ali G
    Nov 22 at 3:54










  • Without loss of gbenerality, you can show if the terminal state $x_1=0$ at time $t_0$, then $x(t)=0$ for all $t>t_0$ .
    – Gustave
    Nov 23 at 14:39










  • What have you done? Perhaps it would be useful to find the solution of the system for $x$. Can you write down this formula?
    – SZN
    Nov 27 at 3:37
















Do you mean a linear time invariant system, because general linear systems also include linear time variant systems?
– Kwin van der Veen
Nov 22 at 0:20




Do you mean a linear time invariant system, because general linear systems also include linear time variant systems?
– Kwin van der Veen
Nov 22 at 0:20












yeah linear time invariant system
– Ali G
Nov 22 at 3:54




yeah linear time invariant system
– Ali G
Nov 22 at 3:54












Without loss of gbenerality, you can show if the terminal state $x_1=0$ at time $t_0$, then $x(t)=0$ for all $t>t_0$ .
– Gustave
Nov 23 at 14:39




Without loss of gbenerality, you can show if the terminal state $x_1=0$ at time $t_0$, then $x(t)=0$ for all $t>t_0$ .
– Gustave
Nov 23 at 14:39












What have you done? Perhaps it would be useful to find the solution of the system for $x$. Can you write down this formula?
– SZN
Nov 27 at 3:37




What have you done? Perhaps it would be useful to find the solution of the system for $x$. Can you write down this formula?
– SZN
Nov 27 at 3:37










1 Answer
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Recall that $dot{x} = Ax + Bu$, then $(A,B)$ is controllable with control law (with minimum energy) given by



$$u(t) = -B^{T}e^{A^{T}(t_1-t)}W_c^{-1}(t_1)(e^{At_1}x_0 -x_1), $$
where
$$W_c(t) = int_0^te^{Atau}BB^{T}e^{A^{T}tau}dtau.$$



For $W_c$ nonsingular, then equivalence is $(A,B)$ is controllable.






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    1 Answer
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    Recall that $dot{x} = Ax + Bu$, then $(A,B)$ is controllable with control law (with minimum energy) given by



    $$u(t) = -B^{T}e^{A^{T}(t_1-t)}W_c^{-1}(t_1)(e^{At_1}x_0 -x_1), $$
    where
    $$W_c(t) = int_0^te^{Atau}BB^{T}e^{A^{T}tau}dtau.$$



    For $W_c$ nonsingular, then equivalence is $(A,B)$ is controllable.






    share|cite|improve this answer

























      up vote
      0
      down vote













      Recall that $dot{x} = Ax + Bu$, then $(A,B)$ is controllable with control law (with minimum energy) given by



      $$u(t) = -B^{T}e^{A^{T}(t_1-t)}W_c^{-1}(t_1)(e^{At_1}x_0 -x_1), $$
      where
      $$W_c(t) = int_0^te^{Atau}BB^{T}e^{A^{T}tau}dtau.$$



      For $W_c$ nonsingular, then equivalence is $(A,B)$ is controllable.






      share|cite|improve this answer























        up vote
        0
        down vote










        up vote
        0
        down vote









        Recall that $dot{x} = Ax + Bu$, then $(A,B)$ is controllable with control law (with minimum energy) given by



        $$u(t) = -B^{T}e^{A^{T}(t_1-t)}W_c^{-1}(t_1)(e^{At_1}x_0 -x_1), $$
        where
        $$W_c(t) = int_0^te^{Atau}BB^{T}e^{A^{T}tau}dtau.$$



        For $W_c$ nonsingular, then equivalence is $(A,B)$ is controllable.






        share|cite|improve this answer












        Recall that $dot{x} = Ax + Bu$, then $(A,B)$ is controllable with control law (with minimum energy) given by



        $$u(t) = -B^{T}e^{A^{T}(t_1-t)}W_c^{-1}(t_1)(e^{At_1}x_0 -x_1), $$
        where
        $$W_c(t) = int_0^te^{Atau}BB^{T}e^{A^{T}tau}dtau.$$



        For $W_c$ nonsingular, then equivalence is $(A,B)$ is controllable.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Nov 27 at 3:57









        Euler....IS_ALIVE

        2,64311338




        2,64311338






























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