Design Tradeoffs of Centralized Versus Distributed Servo Control

This paper details a tool that control specialists can use to select the control platform that provides superior performance by detailing a methodology that investigated the effects of a motion control’s architecture on the performance characteristics of a multi-axis tracking application. The methodology introduced in this paper can be implemented by control specialists easily since it eliminates hardware dependency and allows for easy targeting of the bottlenecks. To test this methodology, this study utilized both centralized and decentralized motion control architectures with a SERCOS interface to personal computer (PC) and programmable automation controller (PAC) based controllers implemented with ladder logic programming techniques. The study found that the bottlenecks migrate as control architectures and components differed. Distributed control outperformed centralized control architectures in each case and PAC-based control platforms outperformed PC-based platforms in servo performance, but PC-based platforms outperformed PAC- based platforms in scan time performance.