In the past decade, parallel manipulators began gaining more attention since they
can outperform their serial counterparts at several areas. The use of common parallel
delta robot mechanisms is wide-spread within the industry, especially for fast pick
and place applications. There is a new type of parallel mechanism on the rise, called
the Generalized Triangle Parallel Robot (GTPR), where the parameters of the robot
may differ from arm to arm. Due to the asymmetric structure, the kinematic description
of such a mechanism is less trivial. For this reason, we wish to show that many mechanical
problems become more straightforward by using screw theory througout the formalism.
Screw theory uses the Plucker coordinate representation of mechanical structures.
This representation leads to an elegant and tractable form of the kinematics equations.
This paper presents a compact tutorial about screw theory and a joint velocity calculation
example, with the complete derivation of screws and numerical results.
