Most robust control schemes for rigid robots assume velocities measurements to be available. Although it is possible to measure velocities by using tachometers, this increases costs, and the signals delivered may be contaminated with noise. Since the use of encoders allows reading joint position pretty accurately, sometimes it is desirable to estimate joint velocities through an observer. This paper presents a robust control scheme designed in conjunction with a linear observer. Uniform ultimate boundedness for the tracking and observation errors are guaranteed. Experiments are included to support the theoretical results and to show that the performance of the new control-observer law is better, in comparison with well-known algorithms reported in the literature.

One of the main practical problems on dexterous robots is the complexity of integrating a large amount of sensors within a small robot architecture. In this brief, the control of cooperative robots, without using velocity measurements, is considered. Our main purpose is to analyze the feasibility of avoiding velocity measurements to manipulate an object firmly. Experimental results are shown to support the developed theory.

Control design of flexible robot manipulators can take advantage of the structural properties of the model used to describe the robot dynamics. Many of these properties are physical characteristics of mechanical systems whereas others arise from the method employed to model the flexible manipulator. In this paper, the modeling of flexible-link robot manipulators on the basis of the Lagrange’s equations of motion combined with the assumed modes method is briefly discussed. Several notable properties of the dynamic model are presented and their impact on control design is underlined.