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Diffstat (limited to 'src/modules/controllib/blocks.cpp')
-rw-r--r-- | src/modules/controllib/blocks.cpp | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/src/modules/controllib/blocks.cpp b/src/modules/controllib/blocks.cpp index c6c374300..0175acda9 100644 --- a/src/modules/controllib/blocks.cpp +++ b/src/modules/controllib/blocks.cpp @@ -293,7 +293,18 @@ int blockIntegralTrapTest() float BlockDerivative::update(float input) { - float output = _lowPass.update((input - getU()) / getDt()); + float output; + if (_initialized) { + output = _lowPass.update((input - getU()) / getDt()); + } else { + // if this is the first call to update + // we have no valid derivative + // and so we use the assumption the + // input value is not changing much, + // which is the best we can do here. + output = 0.0f; + _initialized = true; + } setU(input); return output; } |