  In this article we show how the model predictive path following controller
allows robotic manipulators to stop at obstructions in a way that model
predictive trajectory tracking controllers cannot. We present both controllers
as applied to robotic manipulators, simulations for a two-link manipulator
using an interior point solver, consider discretization of the optimal control
problem using collocation or Runge-Kutta, and discuss the real-time viability
of our implementation of the model predictive path following controller.
