simple_pid 1.0.4
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A simple PID controller. Ported from https://github.com/m-lundberg/simple-pid.

simple-pid-dart #

A simple PID controller. If you want a PID controller without external dependencies that just works, this is for you!

Credit #

This PID code was ported from https://github.com/m-lundberg/simple-pid. Thanks!

Example #

Usage is very simple:


var pid = PID(Kp: 1, Ki: 0.1, Kd: 0.05, setPoint: 1);

// assume we have a system we want to control in controlled_system
var v = controlledSystem.update(0);

while (true) {
    // compute new ouput from the PID according to the systems current value
    var control = pid(v);
    
    // feed the PID output to the system and get its current value
    v = controlledSystem.update(control);
}

Complete API documentation from the original python library can be found here.

Installation #

To install, add to pub spec. This library is null safe.

Usage #

The PID class implements call(), which means that to compute a new output value, you simply call the object like this:

var output = pid(currentValue);

The basics #

The PID works best when it is updated at regular intervals. To achieve this, set sample_time to the amount of time there should be between each update and then call the PID every time in the program loop. A new output will only be calculated when sample_time seconds has passed:

var pid = PID(sampleTime: 0.01); // update every 0.01 seconds (default)

while (true) {
    var output = pid(currentValue);
}

To set the setpoint, ie. the value that the PID is trying to achieve, simply set it like this:

pid.setPoint = 10;

The tunings can be changed any time when the PID is running. They can either be set individually or all at once:

pid.Ki = 1.0;
pid.tunings = [1.0, 0.2, 0.4];

To use the PID in reverse mode, meaning that an increase in the input leads to a decrease in the output (like when cooling for example), you can set the tunings to negative values:

pid.tunings = [-1.0, -0.1, 0];

Note that all the tunings should have the same sign.

In order to get output values in a certain range, and also to avoid integral windup (since the integral term will never be allowed to grow outside of these limits), the output can be limited to a range:

var pid = PID(minOutput: 0, maxOutput: 10);

Other features #

Auto mode

To disable the PID so that no new values are computed, set auto mode to False:

pid.autoMode = false; // no new values will be computed when pid is called
pid.autoMode = true; // pid is enabled again

Observing separate components

When tuning the PID, it can be useful to see how each of the components contribute to the output. They can be seen like this:

List<double> c = pid.components; // the separate terms are now in [p, i, d]

Proportional on measurement

To eliminate overshoot in certain types of systems, you can calculate the proportional term directly on the measurement instead of the error. This can be enabled like this:

proportionalOnMeasurement: true

Tests #

Use the following to run tests:

flutter pub run test

License #

Licensed under the BSD License. Original python simple-pid: Licensed under the MIT License.

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A simple PID controller. Ported from https://github.com/m-lundberg/simple-pid.

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License

BSD-3-Clause (LICENSE)

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