Dear Subscribers,

It was two years ago that I registered the domain name and
started to develop the ParalleMIC web site. Two years of collecting information
and there is still much more to come.

In this anniversary issue, I would like to pay some credit to some of the early
inventors of the popular class of 3-UPU (3-URU, 3PUU, etc.) 3-DOF translational
parallel manipulators. As we mentioned in our review on the peculiar 3-URU
robot (, the 3-UPU manipulator
is known as "Tsai's robot". Indeed, Prof. Lung-Wen Tsai proposed this design
in 1996. It was, therefore, surprising to me to come across Walter Appleberry's
US patent No. 5,156,062 (,
filed in 1991, and disclosing "An anti-rotation positioning mechanism" based
on the 3-UPU/3-URU architecture. The patent rights are now owned by Boeing.

There is another paper that astonished me even more:

* Hunt, K.H., 1973, "Constant-Velocity Shaft Couplings: A General Theory," ASME
  Journal of Engineering for Industry, May, pp. 455-464.

This paper discusses three-chain architectures of a more general class than the
one of 3-UPU mechanisms. Although, the subject of the paper is shaft couplings
that can operate in both "parallel shaft" and "intersecting shaft" modes, the
author actually describes the theory behind the ability of such parallel chains
to purely translate or move in the coupled mode explained in our Review 008
( The paper discloses both
Tsai's and Park's architectures.

1973! No wonder some researchers are pessimistic about discovering new designs.

Best wishes,

Ilian Bonev

January 24, 2002

* Five new patents have been added

* Yet another 6-PUS parallel manipulator with parallel prismatic joints
* An article about Cross Hueller's Specht Xperimental PKM
* Pegasus - the Delta robot is not dead

* The program of the 3rd Chemnitz Parallel Kinematics Seminar is now available

* I will attend the Chemnitz seminar in April and combine the trip with several
  laboratory and company visits. So, we will not lack new material this spring.
* A young LEGO enthusiast is currently preparing a review about his motorized
  spatial and planar Delta robots built out of LEGO parts.
* A new parallel mechanism was noticed in a 1998 US patent. The inventor, a
  NASA scientist, sent me some nice photos of his 3-DOF ion thruster. A short
  review will be published in the coming days.
* Prof. Michael Pohl is almost ready with a review on his HANDLEX parallel
* Polytec PI, Inc. are also preparing a company profile about their hexapods.