U.S. patent application number 14/783154 was filed with the patent office on 2016-02-04 for clamping mechanism, locking arrangement and method of operating reconfigurable manipulator.
The applicant listed for this patent is CENTRUM BADAN KOSMICZNYCH POLSKIEJ AKADEMII NAUK. Invention is credited to Kamil GRASSMANN, Jerzy GRYGORCZUK, Tomasz KUCINSKI, Karol SEWERYN.
Application Number | 20160032609 14/783154 |
Document ID | / |
Family ID | 53040127 |
Filed Date | 2016-02-04 |
United States Patent
Application |
20160032609 |
Kind Code |
A1 |
KUCINSKI; Tomasz ; et
al. |
February 4, 2016 |
CLAMPING MECHANISM, LOCKING ARRANGEMENT AND METHOD OF OPERATING
RECONFIGURABLE MANIPULATOR
Abstract
A clamp mechanism is disclosed, clamping on a tube made of
elastic material, provided with a band clamped on a tube. Inside
the tube, in the location where the band clamps, a stiff element is
located having a diameter substantially corresponding to the inner
diameter of the tube. The band encompasses the tube over the length
of at least the half of its circumference and is connected to a
tensioning and releasing apparatus. A locking system for a
manipulator is also provided including tubes substantially parallel
to each other. Each tube is formed of curling strip wound on a drum
rigidly connected to a structure. The manipulator has at least one
reconfigurable parameter. The system includes a mechanism that is
mounted on each one of tubes. Further, a method of operating a
reconfigurable manipulator is disclosed including curled strip
tubes, wherein the manipulator is provided with a locking system,
which is released for reconfiguration of the manipulator and
clamped for normal operation.
Inventors: |
KUCINSKI; Tomasz; (Elk,
PL) ; GRYGORCZUK; Jerzy; (Warszawa, PL) ;
SEWERYN; Karol; (Krakow, PL) ; GRASSMANN; Kamil;
(Bialystok, PL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CENTRUM BADAN KOSMICZNYCH POLSKIEJ AKADEMII NAUK |
Warszawa |
|
PL |
|
|
Family ID: |
53040127 |
Appl. No.: |
14/783154 |
Filed: |
September 17, 2014 |
PCT Filed: |
September 17, 2014 |
PCT NO: |
PCT/IB2014/064589 |
371 Date: |
October 8, 2015 |
Current U.S.
Class: |
52/108 |
Current CPC
Class: |
E04H 12/18 20130101;
E04H 12/34 20130101; B21C 1/30 20130101; H01Q 1/087 20130101; E04C
3/005 20130101; H01Q 1/1235 20130101; B21C 37/0818 20130101 |
International
Class: |
E04H 12/34 20060101
E04H012/34; E04H 12/18 20060101 E04H012/18 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 6, 2013 |
PL |
PL405939 |
Claims
1. A clamp mechanism, clamping on a tube made of elastic material,
provided with a band clamping on the tube, characterised in that
inside the tube (21), in location where the band (23) clamps there
is located a moulder (22) having a diameter substantially
corresponding to the inner diameter of the tube (21), wherein the
band (23) encompasses the tube (21) over the length of at least
half of its circumference and is connected to tensioning and
releasing means (25, 27, 29).
2. A mechanism according to claim 1, characterised in that the
tensioning and releasing means (25, 27, 29) are attached to the
structure (44, 54).
3. A mechanism according to claim 1 or 2, characterised in that the
tube is partially open and the band (23) has one end (231) attached
to the moulder (22) and is led out through the opening in the tube
(21), wherein its second end (232) is connected with the tensioning
and releasing means (25, 27, 29).
4. A mechanism according to clam 1 or 2, or 3, characterised in
that the moulder (22) is attached to the structure (44, 54), to
which the tensioning and releasing means (25, 27, 29) are attached
too.
5. A mechanism according to claim 1 or 2, or 3, or 4, characterised
in that the tensioning and releasing means are constituted by an
interface (26) attached to the band (23), to which there are
connected a tensioning spring (25) and a string (27) connected with
a drive so that the forces exerted upon the interface by the spring
(25) and a string (27) act oppositely along the same direction,
wherein the magnitude of the force exerted upon the interface (26)
by the string (27) is greater when the mechanism is not clamped,
while smaller when it is clamped.
6. A mechanism according to any of claims 1 to 5, characterised in
that the number of turns formed by the band (23) on the tube (21)
is between one and two.
7. A system locking a multitubular manipulator, characterised in
that on each of the tubes (51a, 51b, 51c) there is mounted a
mechanism according to any of claims 1 to 6.
8. A locking system according to claim 7, characterised in that the
tensioning and releasing means of each of the locking mechanism are
attached to the structure (44, 54).
9. A system locking a multitubular manipulator according to claim 7
or 8, characterised in that the tensioning and releasing means in
the mechanisms locking at least two tubes (51a, 51b, 51c)
constitute interfaces having mounted at one end the tensioning
springs (55a, 55b, 55c), and couplers at the other, wherein the
couplers are connected to a common drive (50).
10. A locking system according to claim 9, characterised in that
the couplers are constituted by strings (57a, 57b, 57c), while the
springs (55a, 55b, 55c) extend radially outside of the system of
tubes so that they are arranged along straight lines intersecting
substantially at one point inside the system of tubes and at that
point there is located an axis (58) on which there are wound the
strings (57a, 57b, 57c) releasing the bands (53a, 53b, 53c)
tensioned by the springs (55a, 55b, 55c).
11. A method of operating a reconfigurable manipulator comprising
curled strip tubes, characterised in that the manipulator is
provided with a locking system according to claim 7, which is
released for reconfiguration of the manipulator and clamped for
normal operation.
12. A method according to claim 11, characterised in that the
parameter of the manipulator subjected to reconfiguration is its
length.
Description
[0001] The invention concerns a mechanism clamping on a tube, a
system locking a set of tubes and a method of operating a
reconfigurable manipulator.
[0002] Tubes curled from strips are used in numerous applications
in devices characterised by the ability to change their length,
which have to combine simultaneously small mass, high durability
and high stiffness. This relates in particular to booms,
manipulators and antennas used in aviation and space exploration. A
tube made of an elastic material, i.e. a material having a high
yield strength, e.g. spring steel, after straightening and winding
on a drum has small size and mass. Upon unwinding it returns to its
nominal form, in which it has been hardened. In this way, after
unwinding the strip from the drum a structure forms again
constituting a thin-walled tube, characterised by a preferable
flexural strength to mass ratio.
[0003] An exemplary implementation with the use of curled strips
mechanism is a manipulator combining a long reach with a small mass
and a small size in folded state disclosed in U.S. Pat. No.
3,601,940. In the folded state the working strip, usually made of
metal, is wound onto a rotational drum. After unwinding the strip
from the drum there appears a structure resembling a thin-walled
tube. Thereby an element is formed with a length adjusted in a
significant range by winding and unwinding the strip from the drum.
Similar solutions have been disclosed in other documents, e.g. U.S.
Pat. No. 3,434,674. In that document preferable ranges of strip
thickness have been indicated and the most typical materials for
their production have been listed; in particular: carbon steel,
stainless steel, beryllium copper, titanium alloys, and fibre
composite materials, e.g. glass or polymer, such as Carbon Fibre
Reinforced Polymer (CFRP).
[0004] A drawback of such structure is that the strip is vulnerable
to damage due to loads transferred by the strip region near the
drum on which the strip is wound. In applications typical for
strips curled into tubes, such as space booms or antennas,
transferring large forces and moments is not necessary. However,
this technology increasingly expands to other fields, like e.g.
servicing manipulators.
[0005] The intermediate region II of the strip vulnerable to damage
is located between the drum on which the flattened strip is wound
and the tube curled from the strip. The strip changes therein its
shape from flat to cylindrical--FIG. 1b. A load applied to the
strip in this region can damage it easily. This problem can be
solved easily in the case of loads acting in perpendicular to the
axis of the curled strip tube. The most typical solution if to use
an additional stiffener in the form of a sliding ring or rolls
through which passes the strip. However, such solution does not
provide protection from loads acting along the tube axis, in
particular resulting in the strip buckling. It is difficult to use
for compensation of such loads known constructional solutions
cooperating with the outer tube surface, such as U-bolts, because
thin-walled curled strip tubes are vulnerable to squeezing as well.
The solution of these problems is the object of the invention.
[0006] This object has been achieved by providing a mechanism
clamping on an elastic tube. The clamp mechanism according to the
invention, clamps on a partially open tube made of elastic material
and locks it with respect to an external structure, with a band.
The mechanism according to the invention has a moulder to which the
band is attached and tensioning and releasing means for tensioning
and releasing the free end of the band. The moulder has a diameter
substantially corresponding to the inner diameter of the tube and
is adapted to be placed inside the tube, the band is adapted to be
led out of the tube through the opening in the tube and
encompassing it over a length of at least half of the circumference
of the tube and to be tensioned with tensioning and releasing means
attached to the structure.
[0007] Preferably the tensioning and releasing means are formed by
an interface having attached: a tensioning spring and a string
connected to a drive so that forces exerted upon the interface by
the spring and the string act oppositely along the same direction,
wherein the magnitude of the force exerted upon the interface by
the string is greater during enforced loosening and smaller during
normal operation.
[0008] Preferably the number of turns formed by the band on the
tube is between one and two.
[0009] The object of the invention has been achieved by further
providing a system locking a multitubular manipulator. Manipulator
has at least two tubes substantially parallel to each other. Each
tube being formed of curling strip wound on a drum rigidly
connected to a structure. The manipulator has at least one
reconfigurable parameter. It further comprises mechanism according
to the invention.
[0010] Preferably the tensioning and releasing means of each of the
mechanisms are attached to the structure.
[0011] Preferably the tensioning and releasing means in the
mechanisms locking at least two tubes constitute the interfaces
having attached to the tensioning springs at one end and couplers
at the other, wherein the couplers are connected to a common
drive.
[0012] Preferably the couplers are strings, and the springs extend
radially outside of the system of the tubes so that they are
arranged on the straight lines intersecting substantially at one
point inside the system of the tubes. At that point there is
located a driven axis on which the releasing strings are wound
tensioned by the band's springs.
[0013] The object of the invention is also achieved by providing a
method of operating a reconfigurable manipulator comprising curled
strip tubes. The manipulator is provided with a locking system
according to the invention, which becomes released for
reconfiguration of the manipulator and tightens for normal
operation.
[0014] Preferably the reconfigurable parameter of the manipulator
is its length.
[0015] The invention has been described in embodiments illustrated
on the drawings, wherein FIG. 1a shows a drum with a strip curled
into a tube known in the art, FIG. 1b shows the strip's transition
from flat shape, enabling winding on the drum, to tubular
shape,
[0016] FIG. 2 shows the locking mechanism according to the
invention,
[0017] FIG. 3a shows an enlarged perspective view of a tube segment
and a band of the mechanism according to the invention clamped
thereon, omitting the interface between the band and tensioning
means, FIG. 3b shows an enlarged perspective view of a band of the
mechanism according to the invention clamped on a tube, with shown
interface between the band and the tensioning means, FIG. 4a shows
symbolically a variable length manipulator in the folded state,
FIG. 4b shows symbolically a variable length manipulator in the
deployed state, FIG. 5a shows a front view of a manipulator with a
boom composed of three tubes, provided with a system according to
the invention, and FIG. 5b shows a perspective view of a
manipulator with a boom composed of three tubes, provided with a
system according to the invention.
[0018] The locking mechanism according to the invention has been
shown in a perspective view in FIG. 2 with the locked open-profile
tube 21. An immovable disc to which the mechanism is attached is
not shown in the figure. Inside the tube 21 there is a moulder 22
having a diameter corresponding to the inner diameter of the tube
21. A band 23 is attached to the moulder 22 and led out outside the
tube through an opening in a partially open tube and wrapped around
its circumference, as show in enlargement in FIG. 3a, where the
interface 26 is omitted for a better depiction of the way the strip
23 is wrapped. Tensioning applied to the band's 23 end causes the
band to clamp on the moulder 22 and to lock the tube with respect
to it. The moulder 22 is made of a stiff material, protecting the
tube against crushing and deformation due to clamping the band 23.
The band 23 is wound around the tube 21 almost twice. It was
verified experimentally that in this situation the band 23 clamps
firmly and effectively after tensioning its end, disabling sliding
the tube with respect to the moulder 22, while it does not remain
clamped after loosening the force tensioning the band's 23 end. The
band 23 has a variable width. On the side of the end 231 attached
to the moulder 22 it is wider, while on the side of the end 232 it
is narrower. The change of the band's width occurs about the half
of its length, i.e. at the distance approximately equal to the
circumference of the tube 21 from each end 231, 232.
[0019] Winding on the tube 21 more than two turns is essentially
pointless. It does not result in better adherence of the band nor
in a greater contact area, while it causes complications by
releasing the locking mechanism. This happens because loosening a
greater number of wound turns requires a wider range of movement of
the band's end having the tensioning force applied to.
[0020] On the other hand, the holding effect can be achieved
leading the band along a half of the tube's circumference, but the
force suppressing sliding of the tube 21 is then weaker.
[0021] To the free end of the band 23 there is attached an
interface 26, connected via a spring 25 with the structure 24, what
has been shown enlarged in FIG. 3b. Tension of the spring 25 is
chosen such that the band 23 effectively locks the tube 21. To the
interface 26 there is connected a string 27 connected to a wheel 29
at a proper distance to its axis, the wheel being driven by a motor
20. The string 27 is directed substantially along the action of the
force of the spring 25 such that as the string 27 is wound onto the
motor driven wheel 29, a force arises which balances the force of
the spring 25 and even slightly greater. Therefore the locking
mechanism according to the invention is locked until switching on
the motor driving the wheel 29. Instead of the motor, wheel 29 and
the string 27 any tensioning or tensioning and releasing means can
be used, such as e.g. bi-positional electromagnets or piezoelectric
drives. The advantage of their use is the speed of operation.
[0022] The mechanism according to the invention can also be
preferably applied for thin-walled tubes having a closed profile.
Then, the moulder 22 is located inside the tube upon which the band
23 clamps, and is not connected with this band but prevents
crushing the tube.
[0023] The mechanism according to the invention can be preferably
applied to solve the problem of compensating forces acting along
the axis of the manipulator comprising curled strips.
[0024] The manipulator according to the invention is symbolically
shown in FIG. 4a in the folded state, while in FIG. 4b in the
deployed state. The manipulator comprises a drum 43 with wound
thereon a strip 41 curling into a tube after unwinding from the
drum. The structure 44 is rigidly attached the drum 43. The locking
mechanism 46 according to the invention is attached the structure
44. During winding and deploying the manipulator, the locking
mechanism 46 unblocks, allowing transition to the deployed state of
the manipulator, shown in FIG. 4b. However, during operating the
manipulator, which can result in longitudinal forces F.sub.x
applied to the operational end 47 of the manipulator and
transferred by the strip curled into the tube 41, the locking
mechanism 46 remains locked. Therefore the longitudinal forces
F.sub.x do not transfer to vulnerable to their action and prone to
deformation region II of the strip curled into the tube 41, but are
transferred via the locking system 46 to the stiff structure 44.
Therefore the longitudinal forces are transferred only via the
region III of the strip curled into the tube, where it has
cylindrical shape, providing sufficient resistance to their
action.
[0025] Transferring transversal forces via strips curled into tubes
requires an application of more than one tube in a single
manipulator. A manipulator with boom comprising three curled strip
tubes has proven to be stable and durable. Such manipulator has
been shown in cross section view in FIG. 5a, and in perspective
view in FIG. 5b. Each of these tubes 51a, 51b, 51c curled from
strips has to be protected against longitudinal forces.
Furthermore, deploying such manipulator is related to the necessity
of synchronizing movement of three strips unwound from drums. There
strips have to be stopped precisely at the same time. Otherwise, an
uncontrolled displacement and/or twisting of the manipulator occur.
In such manipulator the locking mechanism according to the
invention can be particularly preferably used. This is because the
construction of the mechanism according to the invention provides a
very easy possibility of synchronizing a number of locking
mechanism. On each of the tubes 51a, 51b, 51c the clamping
mechanism according to the invention, comprising a band clamping on
the tube having the moulder inside, is attached. The end of each
band is tensioned by a spring 55a, 55b, 55c. The springs 55a, 55b,
55c extend radially outside of the system of the tubes and are
attached to the structure 54 common for all the tubes 51a, 51b,
51c. The straight lines along which the forces of the springs act
intersect at one point inside the system of the tubes. In this
point there is located a wheel 59 driven by a motor 50. Three
strings 57a, 57b, 57c are wound on the axis of the wheel 59.
Because of driving the wheel 59 by the motor 50, the strings 57a,
57b, 57c are winding on its axis simultaneously, synchronously
loosening the bands clamped on the tubes 51a, 51b, 51c. Thereby all
the three mechanisms are released simultaneously.
[0026] It is obvious for a person skilled in the art that this
principle can be implemented in numerous ways by means of means
known in the art. Essential is the configuration of the system
where the bands are clamped by default and arranged such that they
could be loosened by means of one device located substantially
centrally.
[0027] The rigid mechanical connection of the structure 54 with the
drums having strips wound thereon allows to relieve the
intermediate, sensitive region denoted by II in FIG. 1b, FIG. 4a,
FIG. 4b. Because the locking mechanisms are connected with the
structure 54, the forces acting along the strip in the situation,
when the mechanisms are locked, will be transferred to this
structure 54 via a rigid connection, and not a drum nor the
sensitive region II, wherein the strip changes its shape from flat
to circular. Upon releasing the locking mechanisms one retains the
possibility to change the length of the curled strip tube by
rotating the drum, i.e. the fundamental advantage of the curled
strip. A manipulator comprising such system has to be operated in
such a way, that normal operations are performed with the locking
mechanisms locked on the tubes, while the shape of the manipulator
is changed in the conditions of reconfiguration, with the locking
mechanisms unlocked. The manipulator must not be then subjected to
loads acting along the axes of the strips. In the simplest case,
the parameter of the manipulator modified during its
reconfiguration can be its length.
* * * * *