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White Paper: Setting PID Parameters And Notch Filters Using Black's Diagram

Source: Newport Corporation

In the 1800's, automation began with the use of crude motors with belt and pulley drive trains. The concept of motion control systems was not formed until the 1930's. Since then, the motion control platform has evolved greatly in complexity and functionality, achieving performance under load conditions that were not imaginable even 10 years ago.

State-of-the-art systems now commonly targeting specifications in the nanometer range enable the most complex applications e.g. lithography machines. Along with the improvement in hardware performance, and in order to ensure the dynamic performance of motion control systems, the industry has continued to use a theory invented 125 years ago and further refined by Harold Black more than 80 years ago: the mathematical science of proportional-integral-derivative, or PID control.

This discussion will present a graphical method developed by Newport Corporation, based on Black's diagram that greatly reduces the tuning time of complex motion systems. The method relies solely on graphical curve adjustments to define optimum parameters, and results in a tuning that is not an approximation but a real representation of the system's performance. The required theoretical background is minimal, making this intuitive method available to users with some knowledge of transfer functions, servo loops, and notch filters.