![](bg7.png)
trajectory could be realized in the workspace. So
larger trajectories can be tested, for instance, some
trajectory lengths are about 25 mm. The possibility
to make the platform move along longer trajectories
is a major advantage of the measuring system based
on the camera compared to our previous measuring
method. But if the trajectory is longer, it makes sense
that the repeatability performance is lower. Another
advantage of the camera versus the mechanical mea-
suring system is its flexibility and easy implementa-
tion.
6 CONCLUSIONS
In this paper, the XY-Theta Platform is presented, de-
signed with the same mechanical and control compo-
nents of usual industrial robots. But based on a spe-
cific design and control, this platform improves re-
peatability performances significantly. The repeata-
bility performances of this platform have been previ-
ously estimated using the stationary cube method. In
this paper, another method based on a vision system is
used to compute the repeatability performances. The
results of these two methods all point in the same di-
rection: the repeatability in the fine positioning mode
is close to 2µm when the repeatability in the coarse
positioning mode is close to 4 −7µm.
More studies will be performed on this plat-
form. For instance, the platform performances con-
cerning orientation repeatability of the workpiece are
now been investigating. Another scientific interest-
ing topic is the study of the singularities locations in
the workspace, dealing with redundancy and singu-
larities when planning a trajectory from (X
1
, Y
1
, Ω
1
)
to (X
2
, Y
2
, Ω
2
).
The GREAH laboratory is now looking for part-
ners to develop these concepts in industrial or aca-
demic applications with high precision performances.
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