The Original Version
The Agile Eye is a 3-DOF 3-RRR spherical parallel manipulator developed for the rapid orientation of a camera.
Its mechanical architecture leads to high velocities and accelerations. First, the kinematic model of this
manipulator was developed. Then, a geometric optimization was carried out in order to determine the dimensional parameters
which would produce the best accuracy for the mechanism. A complete dynamic model was then established. Finally, a prototype
was designed and built, and a high-performance controller based on a DSP was developed. The prototype was built in 1993 and
has been gaining in popularity ever since.
The workspace of the Agile Eye is superior to that of the human eye. The miniature camera attached to the end-effector can be
pointed in a cone of vision of 140° with ±30° in torsion. Moreover, due to its low inertia and its inherent
stiffness, the mechanism can achieve angular velocities above 1000 °/sec and angular accelerations greater than 20000
°/sec2 which is beyond the capabilities of the human eye.
One of the most interesting topics of research related to the Agile Eye is the analysis of its singularities. Surprisingly,
the singularity loci of the Agile Eye are independent from the chosen branch (there are a total of 8 branches). Note that
for general 3-RRR spherical parallel manipulators, the singularity loci are strictly dependent on the chosen branch.
In addition, in the Agile Eye, there exist four poses for the mobile platform in which arbitrary finite motions of the actuators
do not produce any output at the mobile platform. Finally, the direct kinematic problem of the Agile Eye allows 8 assembly modes.
Poster
A poster on the Agile Eye was prepared in 2002,
and can be downloaded with the following PDF file.
 Two spherical mecanisms: The Agile Eye and SHaDe (12 Mb)
Selected Photos
 |
Several photos of the 3-DOF Agile Eye are provided below.
They can be enlarged by clicking directly on the photo. |
Video Clips
The following video clip illustrate the prototype of the Agile Eye.
 |
Agile Eye
Video clip showing the available degrees of freedom and different types of trajectories, slowly and rapidly.
Format: mpg Length: 1:18 Size: 14.8 Mb
|
The Simplified Version
A simplified 2-DOF version of the Agile Eye has also been recently developed and
patented. Its obvious advantages are very low cost, trivial
inverse kinematics, simplified direct kinematics (only four assembly modes), enlarged workspace, and trivial singularity
analysis. Another interesting feature is that the orientation of the camera (the mobile platform) is completely specified
by an azimuth and an altitude angle, i.e., there is no torsion.
This architecture was also used, in collaboration with the
Computer
Vision and Digital Systems Laboratory (CVDSL), for the development of an
agile stereo pair,
involving two rapid, precise and independent cameras
enabling three-dimensional vision.
Selected Photos
|
Several photos of various versions of the 2-DOF Agile Eye are provided below.
They can be enlarged by clicking directly on the photo. |
Video Clips
The following video clip illustrate the prototype of the 2-DOF Agile Eye.
 |
2-DOF Agile Eye
Video clip showing the use of a laser on the end-effector. The path of the laser can be followed on the ceiling.
Format: mpg Length: 1:05 Size: 12.3 Mb
|
|
