Quadratic approximate dynamic programming for inputaffine systems

We consider the use of quadratic approximate value functions for stochastic control problems with inputaffine dynamics and convex stage cost and constraints. Evaluating the approximate dynamic programming policy in such cases requires the solution of an explicit convex optimization problem, such as a quadratic program, which can be carried out efficiently. We describe a simple and general method for approximate value iteration that also relies on our ability to solve convex optimization problems, in this case, typically a semidefinite program. Although we have no theoretical guarantee on the performance attained using our method, we observe that very good performance can be obtained in practice. Copyright © 2012 John Wiley & Sons, Ltd.