Internet-based client/server virtual instrument designs for real-time remote-access control engineering laboratory

This paper describes the design of a generic Internet-based remote access virtual instrument used for real-time experimentation purposes at Polytechnic University's control engineering laboratory. These instruments can be freely downloaded from the Internet and the remote user can access the laboratory facilities from anywhere and anytime. The system is based on a client/server computer configuration. The server, situated near the experiment, receives command signals transmitted to it by the client. The client remotely computes the command signal based on the reference waveform, and the transmitted system response. The remote user can select the transmission protocol, switch between asynchronous and synchronous sampling, use either a batch or a recursive data transfer mode, and view the experimental test bed. Our approach is distinct from others since it can offer more flexibility and responsibility to the client-side. Issues concerned with network's reliability, dynamic delay factor caused by the Internet's traffic, concurrent user-access, and limited computing power are addressed.