Time delay and data loss compensation for Internet-based process control systems

Abstract

Introducing the Internet into process control systems has brought a lot of benefits and some difficulties to control engineers as well. The major challenge of Internet-based process control systems is how to deal with Internet time delay and data loss. This paper analyses Internet communication features and proposes a control structure with a variable sampling time to overcome the Internet transmission delay. In order to take advantage of the structure fully and attack the major difficulties, two compensation elements have been designed and implemented in the system. These two compensators are located in the feedback and feedforward channels in the architecture respectively. Our simulation and experimental results illustrate that the control structure and two compensation elements can efficiently deal with the Internet time delay and data loss. Our simulation results also show that the time delay and data loss in the feedforward channel seem to cause more serious influence on the control performance and is more difficult to be compensated for.