Internet-Based Control Systems: Overcoming the Time Delay Challenge for Greater Flexibility

Internet and technology are swiftly changing the way people connect and interact with the physical world. The days when endless runs of cable and wiring would characterize computer networks are quickly fading as wireless technologies continue to develop. Internet-based control systems are rapidly gaining popularity due to the convenience and flexibility they offer, unlike the traditional analog systems. The internet-based control systems connect to the company’s internet network ensuring increased scalability, remote system access and management, installation flexibility, cost efficiency and reduction in the need for traditional power outlets. The systems help to create a platform that is more open for system management and integration. The web-based control systems also bring flexibility by making it possible to control a wide range of solutions from a single point or from across numerous sites locally and globally.

The benefits of Internet-based control systems

The biggest difference you will notice with internet-based control systems is that they bring more possibilities, unlike the conventional control systems. The system gives more without costing more. The system is a primary user interface that is provided through web pages that are accessed on a standard browser. Through the system, organizations, departments and employees can monitor conditions, run reports, change schedules, change set points and receive and respond to alarms, among other functions. An internet-based control system is better than the conventional system as it offers more access, flexibility and interoperability over a wider area. The benefits include:

Increased access: Compared to conventional control systems that require special software to be installed on every operator workstation, the internet-based control systems require the installation of particular software only on a single computer, which functions as a web server. The server will generate web pages that will serve as the user interface to the system, unlike the conventional systems that require the installation of the software on every computer that will access the system. Web-based control systems offer increased access by enabling everyone with a legitimate need to use the system access the system at the convenience irrespective of the location or time.

More flexibility: With internet-based control systems, individuals can access the system through any internet-enabled device, including a laptop, PC, and mobile devices. The web-based control systems are more user-friendly as you can respond to a buzz through your smartphone and make the necessary changes from any location. Another benefit of internet-based systems is that they make it easy to manage the system. With the conventional systems, a technician may need the assistance of a college to troubleshoot the system if there is a problem. However, with web-based control systems, the technician can test the system himself.

Greater interoperability: Web-based systems are governed by the set Internet standards, which make systems interoperable at the hardware level. The set standards ensure the web devices can connect to each other, making it easy to make hardware changes, unlike the conventional systems that may be hardware dependent.

A look at how Internet-based control systems work

A well-configured internet-based control system allows individuals to control processing plants remotely over the internet. Establishing a web-based system is not meant to replace an ordinary computer-based control but rather enhances the system to enable control from any location at any time. A good internet based control system should feature at least two-level control architecture, but the system can also have three-level control.

Two-level architecture:  The system includes a lower level and a higher-level control. The lower level should be configured to ensure that the plant is under control even when there is no network communication. The higher level should be configured to offer global access. When designing the system, the lower level should run at a higher frequency to ensure stability while the higher level should run on a lower frequency to improve communication. The two-level controls are designed to work independently. They are also programmed to exchange control commands irregularly. Using a two-level control system ensures that the plant will still be under control even if the network fails. However, it is worth noting that internet-based control system can experience uncertain time-delay problem.

Multirate control scheme: The multi-rate control systems feature the higher and lower levels described in the two-level architecture but with a greater focus on overcoming the uncertain time-delay problem by using a local control system. The lower level runs at a higher frequency to ensure plant stability and the higher level runs at a lower level to reduce communication overload. With this system, there is a need to use a compensator to mitigate the effect of transmission delay.

Conclusion

Internet-based control systems are better than conventional control systems as they are more flexible, more accessible and more interoperable. However, one of the biggest challenges with web-based control systems is the issue of internet time delay. Nevertheless, plants can take advantage of the available solutions to overcome Internet time delay. A multirate control system is more effective in overcoming the variable and unpredictable internet time delay that is caused by internet load and number of nodes than single level control architecture.