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This paper deals with the implementation of a hybrid force/velocity controller for the automatic edge following of two-dimensional unknown planar contours performed by an industrial robot manipulator. In particular, the authors address the problem of compensating the joint friction effects that have to be taken into account in the controller design in order to achieve a reasonable performance with regards to normal force and tangential velocity errors. For that reason, two model-based friction-compensation methods are compared: a static method, based on a previously identified model, and an adaptive method, where joint friction parameters are recursively updated. By means of an extensive experimental activity, it is shown that, in spite of its simplicity and despite the friction effects changing in time during the robot operations, the devised adaptive procedure obtains a high performance in different operating conditions. Index Terms--Adaptation, contour tracking, friction, hybrid force/velocity control, industrial robots.

In the shoe manufacturing process, in order to attach the upper with the corresponding sole, it is necessary to 'scrape' a thin layer of material off the upper surface so that glue can penetrate the leather and adhere; an operation called 'roughing'. This paper describes the design and the implementation of an innovative robotic cell for roughing and cementing of shoe uppers, which operates at the moment in a pilot plant for custom-made shoe production. The small size of the production lots, as required by customization, and the accuracy needed to follow the complex 3D roughing paths, require a considerable degree of flexibility to minimized setup time. In order to meet these severe requirements, the robotic cell, described in this paper, integrates CAD-CAM generated tool paths with the use of a force controlled head, mounted at the manipulator wrist, which allows real-time adaptation of the trajectory in order to ensure continuous and stable contact between the tool and the shoe to be processed, regardless, to a certain extent, of the inaccuracies in the path specification. The paper describes the development details involved in the design of the cell, with a special emphasis on the active head and the overall control architecture. [ABSTRACT FROM AUTHOR]