In 2014, at the International Olympics Space for school
students, Alexandra Arkhipova presented a report on the feasibility of using
joints with flexible elements in walking machines. The author was recognized as
the overall winner (more details: cyclowiki.org). The report suggested: «An
important area of possible application of walking robots would be remote
exploration of other planets». Ten years later, professionals from NASA began
to put this idea into practice: Robot dog trains
to walk on Moon in Oregon trials
(more details: bbc.com). Below we present the text of the
first message about walking machines in space, the ball joint of which contains
a flexible element - an analogue of the ligamentum capitis femoris (LCF).
Arkhipova A.S.
For ten
years of its mission, American wheeled Mars rover vehicle 'Opportunity' covered
just 40 kilometers through the Red Planet, and its twin Spirit got stuck in
sands already in 8 km. A troop of antelope’s gnu is capable of overcoming a
distance up to 50 km a day across country, and mountain goats climb easily indomitable
steeps. Such comparisons demonstrate obviously the advantages of walking as
means of movement in nature.
In comparison
to the side wheel and track machines, an ability of a machine to move by walking
will give it a bigger stability on irregular surfaces, will provide an
opportunity to choose the points of support, will increase its maneuvering
ability and off-road capability, will make it possible to reduce energy costs
per unit of a route, as well as will provide an opportunity to move freely in
the human environment.
In this connection,
many countries are carrying out actively the elaborations of the walking
machines and robots. Walk of the zoomorphic and anthropomorphic walking robots created
for the time being, needs significant energy expenditures, the task of the
support points choosing for pedipulators is not solved to the full extent, and walking
of anthropomorphic robots very often reminds of walking of people with disease.
Owing to this fact, a spectrum of the walking platforms use is restricted
significantly.
Normally, walking
is an automated cyclic process. In a cycle of the person's step, they single out
a period when one leg comes into contact with the bearing surface area, and the
other leg is carried frontwards, as well as a period of a double support,
during which we are supported at once by two legs. Animals' legs, when walking,
may move both one by one and two by two. The robot technicians try to recreate
such walking, verified by the very nature. Walking is a result of the sophisticated
coordinated activities of the skeletal muscles of the body and limbs. Currently,
the analogues of the muscles are used for the walking machinery movement - electric-powered
drives and full hydraulic drives. And what about ligaments? What are they needed
for?
In his thesis
research S.V. Arkhipov showed that the ligament apparatus is necessary for
movement, support of stability and muscular energy saving. Strained ligaments are
capable of relieving muscles and even may give rise to separate movements. Absence
of the analogues of ligaments in the framework of the walking platforms, from
our point of view, is one of the reasons for misfortunes of the developers. One
of the most important ligaments of the person and backboned animals is a ligament
of head of femur. Its tension, when walking, provides an unloading of muscles,
that hold a body, and of the upper sectors of the articular surfaces, as well
as a spontaneous turn of a pelvis frontwards.
By analog with
this joint, we have elaborated for the walking platform an articulated
joint with flexible elements - analogues of ligaments
of the hip joint. In order to study the peculiarities of its functioning, we
have constructed an engineering test bed, which has become a prototype of a
model of an afterbody of a walking platform. When reproducing a single-support period
of a step in the experiment, we reduced an actuator force, holding a framework
of an afterbody of a model. Flexible elements of the artificial joint were
strained gradually, like ligaments on a hip joint, receiving to itself a weight
of a model. Thereby it turned and shifted forth a useful load due to energy transformation
of the general center of mass, raised earlier.
According to
the data of the experiments, the displacement time diagrams of the general
center of mass of the model have been constructed in the sagittal, horizontal
and frontal planes. The movement pattern of the general center of mass of the
model with the articulated joint without flexible elements is
marked with a black bow on the displacement time diagram in the horizontal
plane. Their comparison shows, how the flexible elements, introduced by us into the artificial joint, influence upon
a time-distance graph.
Comparison
of the diagrams has made it possible to construct a spatial time-distance graph
of the general center of mass when modeling a single-support period of the step
of the biomorphic platform.
According to
our calculations, when raising the general center of mass of a model of the afterbody
by 36 mm, we receive a spontaneous forwarding of a useful load by 63 mm, only under
the action of gravity. The calculations show that under moving of the same mass
by way of gliding, a much bigger energy is needed to be spent.
The data of
the experiments have made it possible to optimize the single-support period of
the step of a mobile biomorphic platform. Due to transformation of would-be
energy of the raised general center of mass of the system.
Let us sum
up the totals of my research:
- Walking is
an optimal means of movement across rugged terrain.
- Articulated joint
with flexible
elements of our artificial joint is capable of
creating a rotary moment in the horizontal plane.
- In a single-support
period of a step of a walking platform, it's possible to provide its movement forward
by would-be energy transformation of a useful load weight.
- Walking platform
with artificial joint of our design will make
it possible to reduce costs of energy for a unit of a route.
When creating
the walking platforms for robots and means of transport, we offer to use articulated joints
with flexure elements of our framework, as well as at walk of the walking
platforms - to try to reproduce an algorithm of the natural locomotion.
Robotic engineering, will undoubtedly become widely used in space. Possibly in the future, each cosmic ship and satellite will have its own "repair robot". Such robots are already now eagerly sought at the International Cosmic Station, both for the works in its departments and at its surface in the open space. An important area of a possible application of the walking robots will be a remote investigation of other planets, as well as movement of astronauts and freights across their surface.
Presentation: 2014АрхиповаАС
Citation:
Arkhipova AS. Mobile biomorphic platforms with
analogues of natural locomotion algorithms. Oral presentation at the
International Olympics Space for school students. Korolev, 2014.
Authors & Affiliations
Alexandra Sergeevna Arkhipova
Lyceum of Scientific and Engineering Profile (КОРОЛЁВСКИЙ ЛИЦЕЙ НАУЧНО-ИНЖЕНЕРНОГО ПРОФИЛЯ)
Russia, Moscow Region,
Korolyov
Keywords:
ligamentum capitis femoris, ligamentum teres, ligament of head of femur, stepping platform, walking machine, robot, ball joint, joint with flexible elements
.
MECHANICS AND ROBOTICS
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