Controller Design: Learn How to Build Controllers

[chronie]

Hello all,

I am a Mechanical Engineering junior and I just finished with my first control systems class. I have found the class to be really interesting but it was all theory. I forgot to ask the professor before I left for summer, how do you actually build controllers?

I understand how to use Matlab's control features and everything but is there another program which will help you actually read-in the sensors and program a controller?

 

[edgepflow]

Allan Bradly offers the software for their controllers. You can read sensors, open and close valves, start and stop pumps, energize and cut-out heaters, and so on. You can do PIDs and just tune the constants with the software.

 

[chronie]

Oh okay so they are pretty much already assembled computers.

Let's say I have a temperature sensor connected to my computer and i want to control the temperature in the room with a heater, also connected to my pc.

Would I have to write a computer program and hook up my heater or would I have to buy an Allan Bradly if everything was not connected to my computer?

 

[MATLABdude]

It's possible to read sensors and control actuators with MATLAB as well. The only knock on it is the fact that it's in Java and has a large back end (i.e. may not be suitable for high-performance applications, depending on what said application is).

 

[dlgoff]

Oh okay so they are pretty much already assembled computers.

Let's say I have a temperature sensor connected to my computer and i want to control the temperature in the room with a heater, also connected to my pc.

Would I have to write a computer program and hook up my heater or would I have to buy an Allan Bradly if everything was not connected to my computer?

To do control with your computer, you'll need a way to interface to the input sensor and the heater elements. With an Allan-Bradly controller, the interfaces are self contained and you "set up"/program the controllers parameters to fit your application.

Here's some Allan-Bradly temperature controllers:

Features

Single-loop, high value, ON/OFF, or analog output controllers
1/8 DIN, 1/16 DIN and 1/32 DIN sizes
Various sensor inputs
Auto-tuning and self-tuning available to simplify startup
Heating, cooling, or heating/cooling control available
Manual output control (TC8 and TC16)
High visibility 4-digit, 11-segment status displays
Integral keypad with tactile feedback for setup and modification of parameters
Security modes/levels
Event input (TC8 and TC16) for multiple SP selection, controller RUN/STOP and
auto/manual mode change

http://ab.rockwellautomation.com/Sensors-Switches/Temperature-Sensors/Temperature-Controller#/tab2"

 

[MisterX]

Yes, a computer program would do for a thermostat if they were connected properly to the computer. LabView may be worth mentioning as a program. An embedded solution, perhaps with a microcontroller, is also a possibility. You could even do it as an analog circuit with a comparator.

You may want to have hysteresis so that the heater control does not flicker on and off.Of course there is more to controls than just thermostats.