I'm working with IMU providing me with their orientation to a common global coordinate system. I have created a segment coordinate system from a static posture with know orientations. I have placed two sensors on the thigh, rotated approx. 90 degrees around global Z and 1 on the pelvis. I need to convert the sensor's orientation to the segment CS orientation.
offsetting to 1 frame during standing
q_w_pelvis= q_pelvis[i]*q_pelvis[0].conjugate)
q_w_thigh1= q_thigh1[i]*q_thigh1[0].conjugate)
q_w_thigh2= q_thigh2[i]*q_thigh2[0].conjugate)
rotating segment CS with sensor orientation.
q_segment_pelvis = q_segmentCS_pelvis*q_w_pelvis[i]*q_segment_pelvis[].conjugate)
q_segment_thigh1 = q_segmentCS_thigh1*q_w_thigh1[i]*q_segment_thigh1[0].conjugate)
q_segment_thigh2 = q_segmentCS_thigh2*q_w_thigh2[i]*q_segment_thigh2[0].conjugate)
I did expect thigh1 and thigh2 to result in the same segment CS of the thigh. But it's not the case. How can I achieve the same segment orientation no matter which of the two thigh sensors I use?
