Gümüşel and &#ş;zmen study the dynamic analysis and performance of the proportional (P), proportional + derivative (PD), and fuzzy + integral control methods on a two-link robot manipulator considered for both land and underwater conditions. Numerical simulations of the system were carried out in MATLAB to examine the system’s response for any input. For this reason, the authors developed a computer program to solve nonlinear ordinary differential equations, defining the system dynamics by using the Runge-Kutta algorithm.

In particular, the authors applied modeling to test the control of a two-link robot manipulator with a rigid first link and a flexible second link. They modeled the drag forces by acting on the manipulators that move horizontally under the sea with the flexible link; this seems to be the origin of this study.

The authors evaluated the response of the system, and compared it by applying classical control methods, P and PD control; an intelligent technique; and the integral-augmented fuzzy control method.

According to the authors’ proposed fuzzy + integral method, the integral action takes place when the overshoot is likely to happen under the control of fuzzy logic. They claim that by choosing the appropriate weighting constants, they can drive the robot in both environments without overshoot.

The authors analyze the proposed integral-augmented fuzzy control laws, as well as classical control methods, to drive flexible robots in a wide range of working envelopes, and present the simulation results obtained. Although the authors claim that for the underwater conditions, fuzzy + integral control and PD control give similar responses, compared to the conditions on land, I have some doubts.

In general, this well-written and well-documented work seems to be an interesting and promising line of research. It is intended for professionals in the field of modeling and control of manipulators. The authors also provide a satisfactory literature review of existing relevant research.