Those who have tried to use RealSense in Unity to track the real-life hand whilst the palm is facing towards the chest instead of towards the camera may have found that whilst it is possible, it is problematic: you need to face the palm forward to the camera and do a push-forward to activate tracking and then turn the palm around towards the chest. Even then, tracking can only last for a few seconds before stalling, because the camera can no longer see the palm and so the hand is 'lost.'
There is a way to track the hand consistently whilst keeping it permanently pointed towards the chest though. If you look at your hand, you can see that the knuckles behind the base of the fingers (referred to as the Base joints in RealSense) are prominent on the top of the hand but invisible on the palm-side.
This means that when the palm is facing the camera, it is hard for the camera to see the base joints, but when the hand is turned around they become very visible to the camera.
Therefore, if you set your application to track one of the Base joints instead of Joint_Wrist or Joint_Center (the palm) then an object will not move much when the palm faces the camera, but it will move quickly when the back of the hand (and hence the knuckles) is shown to the camera.
In our own project, we set up an experiment where we placed two TrackingActions in our avatar's shoulder rotation joint, one which tracked the palm and one which tracked the base joint of the index finger. This meant that when the palm faced forwards, the palm would be the primary generator of movement and the index base joint would be largely ignored by the camera due to its low visibility. When the hand was turned round to the chest, the palm tracking would be lost and the index base would become the primary generator of movement.
Our guide to creating multiple numbered TrackingAction scripts to place in the sane object can be found here:
If the project only requires the palm to be pointed permanently towards the chest, then only a single TrackingAction for the finger base joint would be required, making the multiple-TrackingAction method unnecessary.