  The Orthoglide is a Delta-type PKM dedicated to 3-axis rapid machining
applications that was originally developed at IRCCyN in 2000-2001 to meet the
advantages of both serial 3-axis machines (regular workspace and homogeneous
performances) and parallel kinematic architectures (good dynamic performances
and stiffness). This machine has three fixed parallel linear joints that are
mounted orthogonally. The geometric parameters of the Orthoglide were defined
as function of the size of a prescribed cubic Cartesian workspace that is free
of singularities and internal collision. The interesting features of the
Orthoglide are a regular Cartesian workspace shape, uniform performances in all
directions and good compactness. In this paper, a new method is proposed to
analyze the stiffness of overconstrained Delta-type manipulators, such as the
Orthoglide. The Orthoglide is then benchmarked according to geometric,
kinematic and stiffness criteria: workspace to footprint ratio, velocity and
force transmission factors, sensitivity to geometric errors, torsional
stiffness and translational stiffness.
