There are six kinds of different assembly types of UPU chains are summarized by using POC set theory
and on this basis
13 kinds of 3-UPU mechanism are summarized.Then
their structural parameters are analyzed
including POC
DOF and DOC
and some of the mechanisms are used in practice.The results show that the topology structure of those mechanism are different because of different assembly types between kinematic pairs in chains
though the expressions of SOC are same.Lastly
as an example
the pure translation 3-UPU mechanism is optimized in structure which will be as a reference in practical application.