Exact Controllability of a Non-linear Generalized Damped Wave Equation: Application to the Sine-gordon Equation

In this paper, we give a sufficient conditions for the exact controllability of the non-linear generalized damped wave equation ẅ + ηẇ + γAw = u(t) + f(t, w, u(t)), on a Hilbert space. The distributed control u ∈ L2 and the operator A is positive definite self-adjoint unbounded with compact resolvent. The nonlinear term f is a continuous function on t and globally Lipschitz in the other variables. We prove that the linear system and the non-linear system are both exactly controllable; that is to say, the controllability of the linear system is preserved under the non-linear perturbation f . As an application of this result one can prove the exact controllability of the Sine-Gordon equation.