From 39765e002e71a2dd54e932469877acfc1b6fcb67 Mon Sep 17 00:00:00 2001
From: pux <pux@pux.dom>
Date: Thu, 7 Jan 2021 19:39:17 +0100
Subject: add *.exp; (this is redundant information, just to be able to diff
 later on)

---
 exp/FB_PID.EXP | 102 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 102 insertions(+)
 create mode 100644 exp/FB_PID.EXP

(limited to 'exp/FB_PID.EXP')

diff --git a/exp/FB_PID.EXP b/exp/FB_PID.EXP
new file mode 100644
index 0000000..da3b92c
--- /dev/null
+++ b/exp/FB_PID.EXP
@@ -0,0 +1,102 @@
+
+(* @NESTEDCOMMENTS := 'Yes' *)
+(* @PATH := '' *)
+(* @OBJECTFLAGS := '0, 8' *)
+(* @SYMFILEFLAGS := '2048' *)
+FUNCTION_BLOCK FB_PID
+VAR_INPUT				(* ex.: positioning *)
+	IN_xEnable	: BOOL := TRUE;
+	IN_xReset	: BOOL;
+	IN_rW		: REAL; (* ex -> target position *)
+	IN_rX		: REAL; (* ex -> actual position *)
+
+	IN_rKp		: REAL := 1.0;
+	IN_rKi		: REAL := 1.0;
+	IN_rKd		: REAL := 1.0;
+
+	IN_xLimit	: BOOL := FALSE;
+	IN_rLimit 	: REAL := 1024;
+
+	IN_rTa		: REAL; (* sampling rate in s *)
+END_VAR
+VAR_OUTPUT
+	OUT_rY		: REAL;	(* ex. -> set speed *)
+END_VAR
+VAR
+	rESum			: REAL;
+	rE_old			: REAL;
+	rE				: REAL;
+	xWithinLimits	: BOOL;
+	rY_tmp			: REAL;
+	dwReset: DWORD;
+END_VAR
+
+(*
+
+PID CONTROLLER
+Author: mo
+Date: 2019-02
+                              |z
+  w      e               y    v
+  -->( )--->[controller]---->[system]---->
+      ^x                               |
+      |                                |
+      ----------------------------------
+
+Set up PID using Ziegler-Nichols-Method:
+
+1) Ki = 0, Kd = 0
+2) increase Kp until periodic oscillation occurs (and never stops swinging)
+3) this value is Kp_crit
+4) measured period length is T_crit
+5) use this table
+
+   Kp = 0.6 * Kp_crit
+   Tn = 0.5 * T_crit
+   Tv = 0.12 * T_crit
+
+   -> with  [Ki = Kp / Tn]  and  [Kd = Kp * Tv]:
+
+   Kp = 0.6 * Kp_crit
+   Ki = Kp / (0.5 * T_crit)
+   Kd = Kp * (0.12 * T_crit)
+
+e.g.
+Kp_crit = 25
+T_crit = 2s
+
+Kp = 0.6 * 25 = 15
+Ki = 15 / (0.5 * 2s) = 15
+Kd = 15 * (0.12 * 2s) = 3,6
+
+*)
+
+(* @END_DECLARATION := '0' *)
+IF IN_xEnable
+	AND NOT IN_xReset
+THEN
+	rE := IN_rW - IN_rX;
+
+	xWithinLimits := NOT IN_xLimit
+		OR (IN_xLimit AND rY_tmp >= -IN_rLimit AND rY_tmp < IN_rLimit);
+
+	IF xWithinLimits THEN
+		rESum := rEsum + rE;
+	END_IF
+
+	rY_tmp := (IN_rKp*rE) + (IN_rKi*IN_rTa*rEsum) + (IN_rKd*(rE-rE_old)/IN_rTa);
+	OUT_rY := rY_tmp;
+
+	IF NOT xWithinLimits THEN
+		IF OUT_rY >= 0 THEN OUT_rY := IN_rLimit; ELSE OUT_rY := -IN_rLimit; END_IF
+	END_IF
+
+	rE_old := rE;
+END_IF
+
+IF IN_xReset THEN
+	rESum := 0;
+	rE_old := 0;
+	dwReset := dwReset + 1;
+END_IF
+END_FUNCTION_BLOCK
-- 
cgit v1.2.2-1-g5e49