Curious about Control Engineering?

Below we provide some links to Control Engineering resources, but first, a word about Control Loops:

The principle is simple - if you can measure  something in a process and also do something that affects that process in a predictable way then keep checking it and do whatever you can to improve it. If you know how your actions affect the process then you may be able to calculate what actions to take. It's called Feedback.

And the best explanation is a diagram.

There are many applications of control systems - probably more than you realise. You are full of control loops yourself - biological control loops

Eating when you feel hungry
Moving a glass from a table to your lips
Driving a car. How do you think you keep on the road. There is feedback - your Eyes measure the process -, your brain works out what to do and directs the- steering wheel

The control systems this site deals with are those related to engineering systems in manufacturing plants - we call it process control.

There are some fun web sites that show production processes, for example

Yeo Valley 
Ben and Jerry 

These are of course very much simplified. ControlDraw is the sort of thing you use for all the minute detail.

One of the most popular types of control is called PID - Proportional, Integral, and Derivative. This mostly handles  continuous control of a single variable such as temperature. 

Controlling complete factories requires much more than a few PID loops

See also S88 Links for links concerning Batch Control systems.

Academic and Independent Resources

• Control Engineering Virtual Library
• ISA, the International Society for measurement and control
• Home of GRAFCET (SFC)
• World Batch Forum
• With a bit of extra mathematics Control Systems can be very clever indeed. Mark J. Willis and Ming T. Tham at the University of Newcastle (UK) have provided an excellent description of Advanced Process Control, or APC 

Control System Providers

There are many businesses that provide equipment and standard (shrink wrapped) software. Some are large and some are small. We believe that small can be wonderful, and that wonderful can also be big. Here is a mix of the small and the large.

• Honeywell, Emerson, Foxboro,  and Yokogawa are Distributed Control Systems suppliers
• Siemens, Rockwell and Schneider make Programmable Logic Controllers and SCADA products and DCS like systems. You can learn about PLC's from this free online training site
• For SCADA look at Citect and Wonderware, who are a couple of the big boys. 
• For Batch Management take a look at RSBatch, and Wonderware InBatch
• There are also some very interesting Active X Controls from  companies like Kinetica, Global Majic, and the Software Toolbox

Systems Integrators

• Specify the equipment and standard (shrink wrapped) software
• build or get built the hardware
• provide the application software

Some of the large control system suppliers do much of the integration for the systems they sell. This is especially true of DCS suppliers. But there is also a collection of, generally smaller, companies that just provide systems integration, using equipment and software from the PLC and SCADA suppliers. Examples and ControlDraw users are Silchester Controls in the UK, the AN Group in Denmark, Benima/ÅF in Sweden,  EnteGreat in Canada.

Consultants

As represented by Francis of ControlDraw Ltd, Tony Simmons, also in the UK, Jean Vieille in France

News and Information

ControlGlobal from  CONTROL MAGAZINE

The Readout Instrumentation Signpost from Ireland.

The APC Network provides a good collection of Advanced Process Control resources

Copyright © 1998-2009 ControlDraw Ltd. All rights reserved.
Revised: May 15, 2009.