John T. Betts

Learn More
It has been observed that optimization codes are sometimes able to solve state constrained optimal control problems with discretizations which do not converge when used as an integrator on the constrained dynamics. Understanding this phenomenon could lead to a more robust design for direct transcription codes as well as better test problems. This paper(More)
There have been a number of results in the literature showing that a direct transcription numerical approach to optimal control problems could have a number of surprising and desirable behaviors that were not always predicted by the existing theory especially when differential algebraic equations are involved. Most of these results were developed with an(More)
Recent results in the literature have shown that LobattoIIIA methods may have some undesirable stability properties when used to numerically integrate differential algebraic equations (DAEs) which have delays. In these studies Lagrange interpolation was used to compute the delayed terms. Here we show that this undesirable behavior of LobattoIIIA methods(More)
  • 1