Measurement and monitoring

Abstract

Accuracy improvement systems using machines are described and examples are given showing the suitability of mechatronic methods for high-accuracy correction and measurement arrangements. The effectiveness of the application of piezoelectric actuators is demonstrated using the construction of a comparator for angular measurements as an example.Some mechatronic methods for accuracy improvement of multicoordinate machines are proposed. These methods control the accuracy of the displacement of parts of the machine, of the transducers or the final member of the kinematic chain of the machine, such as the touch-probe or the machine cutting tool. Some categories of errors may be improved by numerical control means, because they are determined in the form of a graph with some peaks along the measuring axis running off accuracy limits. These points, as numerical values, are provided as inputs to the control device or to the display unit of the transducer and can be corrected at appropriate points of displacement. The idea is introduced for accomplishing the correction by calculating the correctional coefficients in all coordinate directions and the correctional displacement to be performed using the last (conclusive) part of the machine. For example, the last mentioned part may be the grip of the arm of an industrial robot, the touch-trigger probe of a CMM (measuring robot), the cutting instrument or the holder of metal cutting tools, and so on. In this case piezoelectric plates, in the form of cylindrical or spherical bodies, may be incorporated into the last machine member for this purpose.The experience gained by the authors working at industrial plants and universities, performing EU research projects and international RTD projects, is used throughout the book.