complementary_filter implementation uses wrong threshold value in ScaleQuaternion function

[roboticswithjulia]

Hello,

I was reviewing the imu_complementary_filter implementation and had a quick question regarding the ScaleQuaternion function.

I noticed that the epsilon threshold value at

imu_tools/imu_complementary_filter/src/complementary_filter.cpp

Line 489 in 0fc5161

if (dq0 < 0.0) // 0.9

is set to 0.0. However, the accompanying comment indicates it should be 0.9, which aligns with the value specified in the foundational paper for this filter (https://www.mdpi.com/1424-8220/15/8/19302).

Could you please clarify if the 0.0 value is intentional, or if it should indeed be updated to 0.9? Any clarification would be much appreciated.

Thank you for your time.

Best regards,

Júlia