Abstract
This paper deals with the reconfiguration analysis of a 3-DOF (degrees-of-freedom) parallel manipulator (PM) which belongs to the cylindrical parallel mechanisms family. The PM is composed of a base and a moving platform shaped as equilateral triangles connected by three serial kinematic chains (legs). Two legs are composed of two universal (U) joints connected by a prismatic (P) joint. The third leg is composed of a revolute (R) joint connected to the base, a prismatic joint and universal joint in sequence. A set of constraint equations of the 1-RPU−2-UPU PM is derived and solved in terms of the Euler parameter quaternion (a.k.a. Euler-Rodrigues quaternion) representing the orientation of the moving platform and of the Cartesian coordinates of the reference point on the moving platform. It is found that the PM may undergo either the 3-DOF PPR or the 3-DOF planar operation mode only when the base and the moving platform are identical. The transition configuration between the operation modes is also identified.
Highlights
During the past two decades, a great effort has been made in the research on multi-mode mechanisms ( known as kinematotropic mechanisms, variable-degrees of freedom (DOF)mechanisms, mechanisms with bifurcation or multifurcation and disassembly-free reconfigurableparallel manipulator (PM)), which are a class of reconfigurable parallel mechanisms (PMs)
PMs), which are a class of reconfigurable parallel mechanisms (PMs)
The main issue when dealing with a reconfigurable mechanism is its complete kinematic analysis [4,5], consisting of finding all the operation modes and the transition configurations from one operation mode to an other, which, as it has been noted, represent constraint singular configurations of the PM
Summary
During the past two decades, a great effort has been made in the research on multi-mode mechanisms ( known as kinematotropic mechanisms, variable-degrees of freedom (DOF). The kinematic interpretation of all the 15 possible cases of the values with a vanished component taken by the Euler parameter quaternion to represent orientation of a rigid body has been presented in Reference [8], firstly. This classification is used in this paper for the reconfiguration analysis of the 3-DOF PM under study. The mobility analysis was conducted via an analytical procedure based on the screw theory and the kinematic analysis was carried out by taking into account additional constraints to the UPU legs These constraints forced the UPU legs and the RPU leg to lay on parallel planes in the planar operation mode.
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