improved PID controller

js/pid_controller.js

@@ -0,0 +1,129 @@
+'use strict';
+
+var classes = classes || {};
+
+classes.PidController = function () {
+
+    var self = {},
+        privateScope = {};
+
+    /**
+     *
+     * @type {number}
+     */
+    privateScope.target = null;
+
+    /**
+     *
+     * @type {{P: null, I: null, D: null}}
+     */
+    privateScope.gains = {
+        P: null,
+        I: null,
+        D: null
+    };
+
+    /**
+     *
+     * @type {number}
+     */
+    privateScope.Iterm = 0;
+
+    /**
+     *
+     * @type {{min: number, max: number}}
+     */
+    privateScope.ItermLimit = {
+        min: -1000,
+        max: 1000
+    };
+
+    /**
+     *
+     * @type {number}
+     */
+    privateScope.previousError = 0;
+
+    /**
+     *
+     * @type {{min: number, max: number, minThreshold: number}}
+     */
+    privateScope.output = {
+        min: null,
+        max: null,
+        minThreshold: null
+    };
+
+    /**
+     *
+     * @param {number} value
+     */
+    self.setTarget = function (value) {
+        privateScope.target = value;
+    };
+
+    /**
+     * @param {number} Pgain
+     * @param {number} Igain
+     * @param {number} Dgain
+     */
+    self.setGains = function (Pgain, Igain, Dgain) {
+        privateScope.gains.P = Pgain;
+        privateScope.gains.I = Igain;
+        privateScope.gains.D = Dgain;
+    };
+
+    /**
+     * Sets min and max value for output
+     * @param {number} min
+     * @param {number} max
+     * @param {number} minThreshold if output is below this value, [min] is returned
+     */
+    self.setOutput = function (min, max, minThreshold) {
+        privateScope.output.min = min;
+        privateScope.output.max = max;
+        privateScope.output.minThreshold = minThreshold;
+    };
+
+    /**
+     * Sets upper and lower limit for Iterm accumulator
+     * @param {number} min
+     * @param {number} max
+     */
+    self.setItermLimit = function (min, max) {
+        privateScope.ItermLimit.min = min;
+        privateScope.ItermLimit.max = max;
+    };
+
+    /**
+     * Executes PID controller based on current value and target
+     * @param {number} current
+     * @returns {number}
+     */
+    self.run = function (current) {
+        var error = current - privateScope.target,
+            Pterm = error * privateScope.gains.P,
+            Dterm = (error - privateScope.previousError) * privateScope.gains.D,
+            output;
+
+        privateScope.previousError = error;
+
+        privateScope.Iterm += error * privateScope.gains.I;
+        if (privateScope.Iterm > privateScope.ItermLimit.max) {
+            privateScope.Iterm = privateScope.ItermLimit.max;
+        } else if (privateScope.Iterm < privateScope.ItermLimit.min) {
+            privateScope.Iterm = privateScope.ItermLimit.min;
+        }
+
+        output = Pterm + privateScope.Iterm + Dterm;
+        if (output < privateScope.output.minThreshold) {
+            output = privateScope.output.min;
+        } else if (output > privateScope.output.max) {
+            output = privateScope.output.max;
+        }
+
+        return output;
+    };
+
+    return self;
+};