Applicability of ZigBee for real-time networked motor control systems

Abstract

This paper discusses networked real-time control systems. The common network and ZigBee specific problems are discussed and methods to overcome them are explained. Limitations of ZigBee networks, sources of delay and benefits of broadcast mode over unicast mode for control loop time delay minimization are reviewed. It is explained how play-back buffer, originally used in multimedia play-back, can help to eliminate variance of loop time delay. To cope with achieved constant loop time delay the Smith predictor is used. Performance of control loop utilizing conventional PID controller, Smith predictor and play-back buffer is verified via experiments and proved to be efficient.