Conditional monitoring is crucial for preserving the functionality and longevity of electro-mechanical equipment. The adoption of robots is an effective method for improving the traditional approaches that rely on fixed monitoring sites. Therefore, this work investigates the motion control of a redundant robot manipulator in operational space for the application of conditional monitoring. A simple and efficient kinematic tracking differentiator (KTD) is proposed to convert operational space trajectories into joint space tracking. Redundancy is handled using a null space vector with time delay method. Additionally, a fixed-time terminal sliding mode controller (FxTSMC) is designed with a disturbance observer to improve fast convergence and disturbance rejection ability. Simulation results have been demonstrated to show the effectiveness of the proposed control scheme.