On the potential of lifted domain feedforward controllers with a periodic sampling sequence

Motion control applications traditionally operate with a single-rate, equidistant sampling scheme. For cost reasons, a current trend in industry is consolidating multiple applications on a single embedded platform. Generally, to deal with inter-application interference, a predictable scheduling policy allocates resource to the applications in these platforms. Realizing an equidistant sampling scheme on such shared platform is inflexible and often turns out to be expensive in terms of resource or conservative in terms of performance. The aim of this paper is to investigate the possibilities to relax the equidistant sampling convention. To this end, recent results show that platform timing properties can be represented by a known, precise, and periodically varying set of sampling periods. In view of such predictable platforms, a framework is presented for analysis and synthesis of lifted domain feedforward controllers for periodically time-varying closed-loop systems. Through simulations the potential of such periodically time-varying sampling over conservative equidistant sampling schemes is demonstrated.