Built-in stepped-sine measurements for digital control systems

Mechatronic systems are a class of systems in which the mechanics and electronics are closely intertwined. Examples range from small scale mechanics such as hard disk drives, optical disk drives, and atomic force microscopes (AFMs) [1] to large scale mechanisms such as wind turbines [2]. Mechatronic systems often include multiple lightly damped resonances and/or anti-resonances. The control of these systems involves either restricting the bandwidth to being roughly a quarter of the frequency of the first system resonance or identifying these dynamics and finding a way to mitigate them with the control algorithm [3], [4]. This paper describes a stepped-sine or sine dwell algorithm (also known as swept-sine in the industrial literature) which is built into the real-time controller for precise identification of highly resonant mechatronic systems.