Proportional-Integral-Derivative (PID) control is the most common control algorithm used in industry and has been universally accepted in industrial control. The popularity of PID controllers can be attributed partly to their robust performance in a wide range of operating conditions and partly to their functional simplicity, which allows engineers to operate them in a simple, straightforward manner.
As the name suggests, PID algorithm consists of three basic coefficients; proportional, integral and derivative which are varied to get optimal response. Closed loop systems, the theory of classical PID and the effects of tuning a closed loop control system are discussed in this paper. The PID toolset in LabVIEW and the ease of use of these VIs is also discussed.
PID Theory Explained – [Link]
Matt of SkyLabs has a nice build log about a temperature controlled reflow oven he built using an Arduino based PID controller and a standard toaster oven:
We have successfully managed to build a temperature controlled reflow oven using an Arduino based PID controller and a standard toaster oven from Robert Dyas! This is a must have accessory for any hobbyist who regularly uses surface mount components within their designs. Below we have a build log documenting the process of constructing the oven including:
Teardown of the original oven
Custom enclosure construction
So to start off I will outline a basic parts list of what I used:
Reflow Oven Shield
Solid State Relay
230v AC to 5v DC Power Supply
Custom Laser Cut Enclosure
Temperature controlled reflow oven build – [Link]
Diogoc shared his Hakko T12 soldering controller in the project log forum:
I finally finished my Hakko T12 soldering controller.
Thanks to sparkybg and arhi for all help and sugestions.
Some features of the controller:
– 3310 graphic display
– rotary encoder for easy and fast temperature selection
– sleep mode when the iron is in the stand
– turn off when a long time in sleep mode
– audible indications
– intuitive menu navegation
– percentage visualization of output power
– powered by a compact and lightweight 24V dc laptop power supply
– ambient temperature sensor for a better cold junction compensation
– lcd backlight control
– alarm for very high temperature, turning off immediately the heater
– indication of tip removed to allow hot swapping the tips
– bootloader for easy firmware upgrade via integrated usb port
– usb port and c# software to monitoring all parameters and help to adjust the pid parameters
The controller still need a little adjust in the PID parameters but for me it is almost perfect.
Hakko T12 soldering controller – [Link]
0xPIT @ github.com writes:
This Reflow Oven Controller relies on an Arduino Pro Micro, which is similar to the Leonardo and easily obtainable on eb*y for less than $10, plus my custom shield, which is actually more like a motherboard.
As I believe it is not wise to have a mess of wiring and tiny breakout-boards for operating mains powered equipment, I’ve decided to design custom board with easily obtainable components.
The hardware can be found in the folder hardware, including the Eagle schematics and PCB layout files. It should fit the freemium version of Eagle
Reflow Oven Controller with graphics TFT – [Link]
Carlazar posted pictures of his simple soldering iron driver (SSID) with Arduino PID control. [via]
Main features are:
– Any thermocouple type irons.
– Additional control mode: On-Off controller (besides PID PWM).
– External power supply: Some standard Notebook power supply DC 19V, 4.74A.
– Small dimensions: It fits into 90mm x 110mm x 45mm (WxDxH) box.
– Easy to assemble.
– Simple design: only a few components (besides Arduino).
The HQ soldering iron HQ20/HQ30 (24V, 48W) was used. It has the E-type thermocouple built in (68uV/degC) but you can change that value in software according to the soldering iron that is used (for example K-type is 41uV/degC).
Simple soldering iron driver (SSID) with Arduino PID control – [Link]
Tom posted his Arduino PID controller shield in the dangerous prototypes project log forum:
Program a temperature profile to mash beer or reflow solder. Here’s how.
This full featured open source PID controller uses a DIY stripboard shield for Arduino Uno and compatible boards. Firmware based on osPID massively revamped and extended, blood was sweated over new auto tune routines. Standalone or remote operation over UART using Java GUI. All documented on Github with BOM, schematics, code, pictures etc. Parts cost about $15, external SSR module and Arduino required.
I spun this project as a kit for Tayda, with the idea that all the components could be cheaply ordered in one place.
Open source PID controller (DIY Arduino shield) – [Link]
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]