Controlling temperature has been a prime objective in various applications including refrigerators, air conditioners, air coolers, heaters, industrial temperature conditioning and so on. Temperature controllers vary in their complexities and algorithms. Some of these use simple control techniques like simple on-off control while others use complex Proportional Integral Derivative (PID) or fuzzy logic algorithms. In this project Shawon Shahryiar discusses about a simple control algorithm and utilize it intelligently unlike analogue controllers. Here are the features of this controller:
- Audio-visual setup for setting temperature limits.
- Fault detection and evasive action.
- Temperature monitoring and display.
- Audio-visual warning.
- System status.
- Settable time frame.
- Data retention with internal EEPROM memory.
Intelligent temperature monitoring and control system using AVR microcontroller - [Link]
Hercules Trapierakis writes:
This is a copy paste tool of George’s Homemade Soldering Station but with some improvements and not with a PIC but with an AVR ATMEGA8 uC. I have changed the way that the information is displayed also you can adjust the P I D values and it has a safe mode option – that it will turn off the soldering iron if it is not used for a certain amount of time.
Homemade Soldering Station - [Link]
PID is implemented when a precise way is needed to drive an external device that provides feedback. Heaters with temperature sensors, and servo motors are examples where PID is used.
This app note by Microchip gives instructions how to implement PID control in PIC18 projects. Basic terms are explained inside the document as well as algorithm flow charts to understand how PID is implemented. Microchip has also provided assembler source code to go with this app note. [via]
App note: Implementing PID on PIC18 microcontrollers - [Link]
Giorgos Lazaridis writes:
If you have work with some kind of industrial or marine automation, then most probably you’ve heard before the term PID. PID controllers are very common in closed-loop systems today. Here is how this system can calculate and minimize the error with great precision.
The whole story began as a marine application, when people were trying to find ways to make reliable and accurate ship steering systems. But the problem was that, if the automation turns the rudder let’s say left, the ship will not turn instantaneously, instead it needs a long course, for ships do not steer like like cars, instead they have a big hysteresis. Another problem is also that when the ship finally turns to the right direction and the automation turns the rudder straight, the ship keeps turning left due to inertia and many other parameters like waves, wind, speed etc.
At first, proportional systems were developed to do this. A proportional systems reads the feedback (electronic compass) and turns the rudder according to the angle that the ship needs to turn. If for example the ship had to turn 45 degrees left, the rudder would turn 20 degrees, and as the ship slowly turns to this direction, the rudder decreases its angle proportionally. But this system has a great disadvantage: Either the rudder will oscillate left and right because the ship will never stay on course precisely due to external disturbances, or the system will stabilize with a small constant error in angle.
PID Theory - [Link]
We’ve been working hard over the last several months to build a fully-featured, open source PID controller that’s every bit as capable as its closed brethren.
(If you’re so inclined, there’s also a post on my personal blog with some introductory videos)
osPID – Open Source PID Controller - [Link]
Line follower simulator. [via]
A model of differential driven wheeled robot is implemented. The width of the line sensor, the line sensor position and the wheel gauge (distance between the two wheels) can be adjusted.
Apart from the geometry settings, there is also a possibility to adjust the motor behavior. The “acceleration” scrollbar sets how quickly the robot chassis reacts to commands form the PID regulator.
Line follower simulator - [Link]
I plan to make a pre-heater for my SMD works, and i will need a controller for the air heater. From my job i know the PID controllers and how efficient they are, but i did not really know how they work. After some research i did, i sound the “secrets” of the PID systems (and i also wrote a theory for PID systems). So, now i feel ready to turn theory into product. Many will say again that i could spent $40 to get a PID controller… Yes, i know… But i DON’T want to. For me, making projects is not a chore, it is my hobby, i do it for fun.
K-Type Thermocouple PID Controller - [Link]
Stian made this awesome sous-vide temp. controller, which he calls the “SousVide-O-Mator”. Built around an ATMega328 with the Arduino bootloader, it uses a DS18B20 temp. probe to monitor the temp, a 20×4 LCD to communicate with the user, and a solid-state relay to switch the rice cooker on and off. It also features one of the neatest, cleanest stripboard layouts I’ve ever seen (style counts!). He writes:
My brand spanking new homemade Sous Vide controller (PID controller for cooking). By connecting the relay to my rice cooker and putting the probe and a small aquarium pump inside I’m able to very accurately control the water temperature..
This is basically a heating immersion circulator as used by some fancy restaurants – readily made equipment cost in the range of $1000.. So I made one myself on the cheap (controller + rice cooker + water pump). This can be used to cook meat to perfection
Perfect for Sous Vide cooking! ( For more information about Sous Vide: http://en.wikipedia.org/wiki/Sous-vide )
SousVide-O-Mator - [Link]
Most of us simply can’t afford an industrial reflow oven and this pain was also felt by the folks over at Rocket Scream Electronics. So armed with an idea and some help from the Adafruit Reflowduino sample code, the Reflow Oven Controller Shield was born. The shield is based off the familiar MAX6675 Thermocouple Amplifier and the PID library written by Brett Beauregard.
Toss in a few solid sate relays (SSR) and a K-Type Thermocouple, like the ones Adafruit has here, and your good to go. I like the idea of a standalone PID controller as it’s one less PC controlled device to worry about. [via]
Reflow Oven Controller Shield - [Link]
Designing a simple and yet functional Line Follower Robot (LFR) is always a fascinating and challenging subject to be learned, the LFR actually could be implemented in many ways start from a simple two transistors to a sophisticated PID (Proportional, Integrate and Differential) which take advantage of the programmable feature of microcontroller to calculate the PID equation to successfully navigate the black track line on a white background surface.
The LM324 Quad Op-Amp Line Follower Robot with Pulse Width Modulation - [Link]