A numerical solution approach for non-smooth optimal control problems based on the Pontryagin maximum principle

We consider nonsmooth optimal control problems subject to a linear elliptic partial differential equation with homogeneous Dirichlet boundary conditions. It is well-known that local solutions satisfy the celebrated Pontryagin maximum principle. In this note, we will investigate an optimization method that is based on the maximum principle. We prove that the discrepancy in the maximum principle vanishes along the resulting sequence of iterates. Numerical experiments confirm the theoretical findings.