Discrete-time stability analysis of a control architecture for heterogeneous robotic systems

The aim of this paper is to investigate the discrete-time stability of robot motion control in the task space. The control system has been modeled as a classical inner-loop/outer-loop architecture, adopted in several industrial robotic systems. The inner-loop is composed of a servo-level joint controller, and higher level kinematic feedback is performed in the outer-loop. Heterogeneous dynamics is considered in the inner-loop, which can for instance describe redundant coordination/synchronization control systems with cooperative robots with non-identical dynamical responses. There are surprisingly few discrete-time stability results in the current state-of-the-art for this popular control architecture. The qualitative effects of the inner-loop dynamics on the overall stability of the system is investigated, and improved outer-loop feedback gain margins are derived.