On "Stability and control of elastic-joint robotic manipulators during constrained-motion tasks"

In the original paper by J.K. Mills (ibid., vol.8, p. 119-26, 1992), a singularly perturbed model of an elastic-joint robotic manipulator has been presented. The author shows that the expression of the boundary layer subsystem is incorrect. The correct expression is given and it is shown that, for a control system designed for rigid robots, the uniform exponential stability of the boundary layer system, required for the application of Tikhonov's theorem, can still be proven.