Lambda Tuner

Lambda Tuner

A process engineer tool...

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Lambda tuner is a tool for tuning PID controllers in industrial processes. It's using the "Lambda method" to calculate the parameters with the help from four process values. This tool is designed for "PID ideal algorithm". That's the most common algorithm used. For simplicity, parallel and serial algorithm is not included.

In version 1.2 there is a test function included, where you can visualize how the controller will react with your settings. The function is using a process model and a PID calculation to generate the results. But a process model is only a model, your process is always more complex. It will not be 100% correct, but it gives you an idea of how it going to behave.

Lambda Tuner Graph Integrating Loop test

Self- and integrating- control

First you need to enter the controllers min and max value, default is 0-100 %.
Next is to identify your process type. There are two major types of processes, the self-controlling and the integrating type.
Self-controlling processes will always reach a steady state, if you put it in manual and make an output change. Flow control is the best typical example.
Integrating processes will not reach a steady state if you do the same. Level control is a typical example.

Use trendtool to examin tuning values

To obtain the process values you need to do a bump test. Put the controller in manual an make an output change. Watch the process value change, how much and how fast. Use a trend tool if it's available. First enter how big change you made in ΔOUT, typical is 5 or 10%. Next check how long time in seconds it took from the output change until the process value start responding, thats your DEAD TIME. Normally this is only some seconds, but if you have conveyors feeding a level control it can be minutes.

For the last two values, its depending on the process type how measure them.
For the self-controlling:
Check how much the process value changed in total, thats your ΔPV. Last value needed is the TIME parameter, note that the time is measured from the start of bump test until process value reaches 63% of the total change in seconds. That is usually similar to ¼ of the total change time.
For the integrating:
You need to determine a TIME in seconds. Long enough to make a measurable change in the process. Enter your time and how big impact your change had on the process.

Lambda Tuner Graph Self Control Loops

There is a backdrop that's graphical trying to explain this. Activate it by swiping left. After that you can change process type by swiping left or right. After that you change the Lambda!
The Lambda is a value of how you want your controller to react. Fast and aggressive working as fast as possible or slow and steady, or anything in between. Thats is depending on the process and the needs for your installation. Fast is often preferred but can give oscillating loops if the conditions are changing a lot. Slow is often kinder to the equipment.

Evaluate the PID parameters

For the self-controlling loop you will see a text that is telling you how fast your loop will reach the setpoint, if you are using the proposed parameters. You will get a warning you if you try to control the process faster than it is physically possible. You can also use that information if you want to give two parallel loops the same reaction time. Simply adjust the lambda until the loop has the desired reaction time.

Testing the self-controlling loop.

Lambda Tuner Graph Self Control Loop Test

For the integrating loop the text will tell you how much the process value will change, if the process load changing 100%.

Lambda Tuner Graph Integrating Loops

Example: If the output needs to travel from 100% to 0% in a level control. How far from the setpoint will the process value stop. A tank for instance, is often used as a buffer. If the setpoint is set to 50% the level can change 40% without risking the tank to overfill and still using the buffer size as good as possible.

Testing the integrating loop.

Lambda Tuner Graph Integrating Loop Test