  While Product of Exponentials (POE) formula has been gaining increasing
popularity in modeling the kinematics of a serial-link robot, the
Denavit-Hartenberg (D-H) notation is still the most widely used due to its
intuitive and concise geometric interpretation of the robot. This paper has
developed an analytical solution to automatically convert a POE model into a
D-H model for a robot with revolute, prismatic, and helical joints, which are
the complete set of three basic one degree of freedom lower pair joints for
constructing a serial-link robot. The conversion algorithm developed can be
used in applications such as calibration where it is necessary to convert the
D-H model to the POE model for identification and then back to the D-H model
for compensation. The equivalence of the two models proved in this paper also
benefits the analysis of the identifiability of the kinematic parameters. It is
found that the maximum number of identifiable parameters in a general POE model
is 5h+4r +2t +n+6 where h, r, t, and n stand for the number of helical,
revolute, prismatic, and general joints, respectively. It is also suggested
that the identifiability of the base frame and the tool frame in the D-H model
is restricted rather than the arbitrary six parameters as assumed previously.
