For linear time-invariant systems, a separation principle holds: stable observer and stable state feedback can be designed for the time-invariant system, and the combined observer and feedback will be stable. For non-linear systems, a local separation principle holds around steady-states, as the linearized system is time-invariant. This paper addresses the issue of a non-linear separation principle on Lie groups. For invariant systems on Lie groups, we prove there exists a large set of (time-varying) trajectories around which the linearized observer-controler system is time-invariant, as soon as a symmetry-preserving observer is used. Thus a separation principle holds around those trajectories. The theory is illustrated by a mobile robot example, and the developed ideas are then extended to a class of Lagrangian mechanical systems on Lie groups described by Euler-Poincare equations.
Optimal output-feedback control and separation principle for Markov jump linear systems modeling wireless networked control scenarios (extended version)
A Nonlinear Separation Principle via Contraction Theory: Applications to Neural Networks, Control, and Learning
Center for Control, Dynamical Systems, and Computation, UC Santa Barbara（控制、动态系统与计算中心，加州大学圣巴巴拉分校）；Department of Electronics and Telecommunications, Politecnico di Torino（电子与电信系，托里诺理工学院）；Graduate School of Advanced Science and Engineering, Hiroshima University（先进科学与工程研究生院，广岛大学）
