Comments on "Hamiltonian adaptive control of spacecraft" by J.J.E. Slotine and M.D. Di Benedetto

In the adaptive scheme presented in the original paper (ibid., vol.35, no.7, p.848-52, 1990) for attitude tracking control of rigid spacecraft, the spacecraft is parametrized in terms of the inertial frame. The commenter shows how a parameterization in body coordinates considerably simplifies the representation of the adaptation scheme. The new symbolic expression for the regressor matrix is easy to find even for six-degree-of-freedom (DOF) Hamiltonian systems with a large number of unknown parameters. If the symbolic expression for the regressor matrix is known in advance, the computational complexity is approximately equal for both representations. An example illustrates the advantage of the new representation when modeling a simple three-DOF model of the lateral motion of a space shuttle. >