Servo amplifier (servo "drives ) vendors do not provide customers with any means to analytically servo tune their products. This paper presents an analytic method for tuning servo amplifiers without expensive controls software, and without actual hardware, test utilities, or "on site" servo tuning, by using "Straight Line" Bode plots. This technique permits control system users to analytically tune their amplifiers rather than having to empirically tune them. This is the first in a series of papers to present techniques to allow servo amplifier users to analytically integrate their drives; this paper presents the Straight-Line Bode plotting method and outlines tuning current loops. The second paper will cover tuning velocity loops, again using Straight Line Bode plots. The third paper will address proper tachometer scaling and buffering, and will present a "rules based" system level tuning method. All these papers will be written to enable users to analytically tune their servo amplifiers, to replace or augment the empirical method all vendors provide, with an end goal of creating auto tuning software. Straight Line Bode plots are asymptotic line Bode plots. As no commercial software to create these Bode plots was found, a method will first be presented to create them quickly and inexpensively. The method can be implemented in MatLab M. files, VB code, or in Excel. These models and tuning techniques are being used by Sheffield Measurement, a division of Hexagon Metrology, for servo tuning its current loops and velocity loops on their CNC Coordinate Measuring Machines (CMMs), over a wide range of machine styles and sizes. This technique allows CMMs to be servo tuned "off line", so that little or no "on site" servo tuning is required. This is an important tool as the task of integrating CMM machine controllers to 3~rd party CMM's is a growing market segment. These models apply equally well to all industrial servo drives.
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