Chapter F Problem Sheet 6 (Lectures 12–13)

  • 1. Consider the first order scalar differential equation

    \[ \dot {x}+2x=4u. \]

    • (a) Write this in the standard form \(\dot {x}=Ax+Bu\).

    • (b) Determine the Kalman controllability matrix and use this to show that the system is controllable.

    • (c) Determine the Hautus controllability matrix and use this to show that the system is controllable.

    • (d) Determine the controllability Gramian \(Q_T\) and use this to show that the system is controllable. Moreover, determine a control which steers the system from a given \(x^0\in \mR \) to a given \(x^1\in \mR \) in a given time \(T>0\).

    • (e) Determine the infinite-time controllability Gramian \(Q\) by solving the control Lyapunov equation and use this to show that the system is controllable.

  • 2. Consider the second order scalar differential equation

    \[ \ddot {q}+q=u. \]

    • (a) Write this in the standard form \(\dot {x}=Ax+Bu\) with \(x:=\sbm {q\\\dot {q}}\).

    • (b) Determine the Hautus controllability matrix and use this to show that the system is controllable.

  • 3. For the input-state system \(\dot {x}=Ax+Bu\) with

    \[ A=\bbm {5&4\\-3&-2},\qquad B=\bbm {1\\-1}, \]

    determine the reachable subspace.

  • 4. Determine whether or not \(\dot {x}=Ax+Bu\) is controllable when

    \[ A=\bbm {0&1&-1\\2&1&0\\-3&5&1},\qquad B=\bbm {1\\0\\1}. \]

  • 5. Determine whether or not \(\dot {x}=Ax+Bu\) is controllable when

    \[ A=\bbm {0&1&2\\0&1&5\\0&0&1},\qquad B=\bbm {1&0\\0&1\\0&1}. \]

  • 6. Solve the control Lyapunov equation for

    \[ A=\bbm {-2&0\\0&-3},\qquad B=\bbm {1\\2}. \]

  • 7. Show using only the definition of controllability that \(\dot {x}=Ax+Bu\) with

    \[ A=\bbm {1&0\\0&1},\qquad B=\bbm {1\\2}, \]

    is not controllable, i.e. show that for all \(T>0\) there exist \(x^0,x^1\in \mR ^2\) such that there does not exist a control \(u:[0,T]\to \mR \) we have \(x(0)=x^0\) and \(x(T)=x^1\).