From dc612d75c788bc8b2a90c200a13a5a5a0e3a68d9 Mon Sep 17 00:00:00 2001
From: Thomas Gubler <thomasgubler@gmail.com>
Date: Fri, 18 Jul 2014 00:15:16 +0200
Subject: BlockDerivative: initialize in first run

---
 src/modules/controllib/blocks.cpp | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

(limited to 'src/modules/controllib/blocks.cpp')

diff --git a/src/modules/controllib/blocks.cpp b/src/modules/controllib/blocks.cpp
index c6c374300..04cb023a8 100644
--- a/src/modules/controllib/blocks.cpp
+++ b/src/modules/controllib/blocks.cpp
@@ -293,7 +293,12 @@ int blockIntegralTrapTest()
 
 float BlockDerivative::update(float input)
 {
-	float output = _lowPass.update((input - getU()) / getDt());
+	float output = 0.0f;
+	if (_initialized) {
+		output = _lowPass.update((input - getU()) / getDt());
+	} else {
+		_initialized = true;
+	}
 	setU(input);
 	return output;
 }
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