Ok so I have been trying to find out shoulder joint angles from a kinect RGB-D camera.My end goal is to acquire these angles to feed them to a robotic arm (7DoF - 3 shoudler 1 elbow 3 wrist) and control the arm motion just with the camera and body movement. So far I have been successful in calculating the elbow joint angle just by using simple vector algebra. I am also able to acquire their coordinates in mm using the body tracking sdk. However, when I used a similar approach to find the shoulder joint angles it didnt work very well as even If I moved my arm about a particular axis it would change the angles of the other 2 axes also. So I decided to change the approach by using quaternions which were included in the azure kinect body tracking sdk. ( I am using python so I had to use a wrapper named pykinect). I am now stuck at how I am supposed to get the shoulder joint angles with this approach as I tried converting these quaternions to 3 coordinate axes by a rotation matrix.Further I decided to use DH paramters to somehow get the angles but the problem is dh paramters is mainly used in Forward kinematics so I am not sure how to use it. Basically I can get 3 of the 4 parameters ( angle being unknown) for every joint from chest to shoulder ( I have converted the 3 DOF system into 3 single DOF systems.
Also I have been reading articles and slides to understand DH
Pls help me identify the problems and some solutions or recommendations.