Comments on "Redesign of hybrid adaptive/robust motion control of rigid-link electrically-driven robot manipulators"

—The above paper 1 presents the design of an adaptive/robust controller for uncertain electrically-driven robots with no velocity measurements. This note shows that the claim that velocity measurements are not required for control implementation is incorrect. This note addresses the adaptive/robust controller proposed in the above paper 1 by Su and Stepanenko for the position control of uncertain , electrically-driven robots without velocity measurements. In the paper, the authors claim that the implementation of the proposed control law does not require joint velocity measurements; however, this claim is invalid due to the reasons described in the following discussion. In the above-mentioned paper, a linear parametrization of the robot dynamics is defined as shown below where 8 a (1) 2 n2nm is a regressor matrix, a 2 nm is an unknown , constant parameter vector, q(t) 2 n is the joint position vector, and _ q d (t);  q d (t) 2 n denote the desired velocity and acceleration trajectory vectors, respectively. A new unknown parameter vector is then defined as follows: