Recursive Newton-Euler algorithms, DH notation

In order to apply the RNE as presented in [13], let us define the following
variables (referenced in the i^{th} coordinate frame if applicable):

- σ
_{i}is the joint type; σ_{i}= 1 for a revolute joint and σ_{i}= 0 for a prismatic joint; - p
_{i}=^{T }is the position of the i^{th}with respect to the i - 1^{th}frame; - z
_{0}=^{T }