U.S. patent number 3,794,128 [Application Number 05/310,206] was granted by the patent office on 1974-02-26 for subterranean penetrator steering system utilizing fixed and rotatable fins.
This patent grant is currently assigned to Bell Telephone Laboratories, Incorporated. Invention is credited to Paul Francis Gagen, Charles Elmer Jones, Jr..
United States Patent |
3,794,128 |
Gagen , et al. |
February 26, 1974 |
SUBTERRANEAN PENETRATOR STEERING SYSTEM UTILIZING FIXED AND
ROTATABLE FINS
Abstract
A steering system for a subterranean penetrator includes a fixed
fin and a rotatable fin. The fixed fin is advantageously attached
to the exterior rear portion of the penetrator at an angle of
approximately 25.degree. with the penetrator's longitudinal axis.
The rotatable fin is located diametrically opposite to the fixed
fin, the axis of rotation thereof being perpendicular to and
intersecting the penetrator's longitudinal axis. An associated
actuating mechanism located within the penetrator adjustably
orients the position of the rotatable fin. Rotation of the
penetrator about its longitudinal axis is effected when the
rotatable fin is antiparallel to the fixed fin or to a lesser
degree when the rotatable fin is substantially parallel to the
penetrator's long axis. Curvilinear penetrator motion along the
desired steering plane is effected when the rotatable fin is
parallel to the fixed fin, the axis of rotation of the rotatable
fin being perpendicular to this plane. In one embodiment of this
invention, the rear portion of the penetrator which houses the fins
is inwardly tapered at approximately 4.degree. to allow use of
substantially smaller fins and/or produce higher steering rates for
a given length penetrator. It is an advantage of this invention
that it does not require the articulatable tail and its associated
actuating mechanism of prior art subterranean penetrators.
Inventors: |
Gagen; Paul Francis (Westfield,
NJ), Jones, Jr.; Charles Elmer (Fairfield, NJ) |
Assignee: |
Bell Telephone Laboratories,
Incorporated (Murray Hill, NJ)
|
Family
ID: |
23201445 |
Appl.
No.: |
05/310,206 |
Filed: |
November 29, 1972 |
Current U.S.
Class: |
175/73;
175/19 |
Current CPC
Class: |
E21B
7/26 (20130101); E21B 7/068 (20130101) |
Current International
Class: |
E21B
7/26 (20060101); E21B 7/04 (20060101); E21B
7/06 (20060101); E21B 7/00 (20060101); E21b
007/08 () |
Field of
Search: |
;175/19,73,94,26,92 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Purser; Ernest R.
Assistant Examiner: Favreau; Richard E.
Attorney, Agent or Firm: Graves; C. E.
Claims
What is claimed is:
1. A system for controlling the motion of a subterranean penetrator
along a soil medium, said penetrator having a cylindrical housing
and said system comprising:
a first fin fixedly attached to the exterior of said housing, said
first fin making a first positive angle with the longitudinal axis
of said housing;
a second fin located diametrically opposite to said first fin and
being rotatable relative to said housing, the axis of rotation of
said second fin being perpendicular to and approximately
intersecting said longitudinal axis; and
actuating means located within said housing for rotatably orienting
the position of said second fin;
curvilinear penetrator motion along the plane which is
perpendicular to the axis of rotation of said second fin being
effected when said second fin is parallel to said first fin;
and
forward penetrator motion being effected when said second fin makes
a negative angle with said longitudinal axis, superimposed
penetrator rotation about said longitudinal axis occurring
simultaneously therewith.
2. The system of claim 1 wherein said first positive angle is
approximately 25.degree. .
3. The system of claim 1 wherein said first positive angle has a
maximum value equal to the slip angle of said soil medium.
4. The system of claim 1 wherein forward penetrator motion is
effected when said second fin makes a negative angle with said
longitudinal axis equal in magnitude to said first positive
angle.
5. The system of claim 1 wherein said second fin is idle, said
second fin assuming a small negative angle relative to said
longitudinal axis.
6. The system of claim 1 wherein said first and second fins are
located at the rear end of said penetrator housing.
7. The system of claim 6 wherein said rear end of the penetrator
housing is inwardly tapered at a second positive angle which is
substantially less than said first positive angle.
8. The system of claim 7 wherein said second positive angle is
approximately 4.degree. .
9. The system of claim 7 wherein said fins are located towards the
rear of said tapered rear end.
10. A system for controlling the motion of a subterranean
penetrator along a soil medium, said penetrator having a
cylindrical housing and said system comprising:
a first fin fixedly attached to the exterior rear portion of said
housing, said fin making a first positive angle of approximately
25.degree. with the longitudinal axis of said housing;
a second fin located diametrically opposite to said first fin and
being rotatable relative to said housing, the axis of rotation of
said second fin being perpendicular to and approximately
intersecting said longitudinal axis, the rear portion of said
housing including said first and second fins being tapered at a
second positive angle of approximately 4.degree.; and
actuating means located within said tapered rear portion for
rotatably orienting the position of said second fin,
curvilinear penetrator motion along the plane which is
perpendicular to the axis of rotation of said second fin being
effected when said second fin is parallel to said first fin;
and
forward penetrator motion being effected when said second fin makes
a negative angle with said longitudinal axis equal in magnitude to
said first positive angle, uniform penetrator rotation about said
longitudinal axis occurring simultaneously therewith.
11. A system for controlling the motion of a subterranean
penetrator along a soil medium, said penetrator having a
cylindrical housing and said system comprising:
a first fin fixedly attached to the exterior of said housing, said
first fin including an upper surface and a lower surface and making
a first positive angle with the longitudinal axis of said
housing;
a second fin located diametrically opposite to said first fin and
being rotatable relative to said housing, said second fin including
an upper surface and a lower surface, the axis of rotation of said
second fin being perpendicular to and approximately intersecting
said longitudinal axis; and
actuating means located within said housing for rotatably orienting
the position of said second fin;
curvilinear penetrator motion along the plane which is
perpendicular to the axis of rotation of said second fin being
effected when the lower surfaces of said fins make contact with the
oncoming soil; and
forward penetrator motion being effected when the lower surface of
said first fin and at least the upper surface of said second fin
make contact with the oncoming soil, superimposed penetrator
rotation about said longitudinal axis occurring simultaneously
therewith.
Description
FIELD OF THE INVENTION
This invention relates to subterranean penetrators or "moles" and,
in particular, to a steering system therefor.
BACKGROUND OF THE INVENTION
Subterranean penetrators are being utilized to form underground
tunnels for the placement of utility services such as telephone or
electrical cables. Such subterranean penetrators generally include
means for effecting the propulsion, detection, and steering
functions. Advantages of subterranean penetrators over prior cable
burial methods are increased speed of operation and lack of
disruption of the ground surface.
Both hydraulically and pneumatically propelled subterranean
penetrators are known. For example, Zinkiewicz U.S. Pat. No.
3,137,483 and Zygmunt U.S. Pat. No. 3,407,884 disclose
pneumatically powered subterranean penetrators while Southworth
U.S. Pat. No. 3,465,834 discloses a hydraulically driven
version.
Several subterranean penetrator steering systems are also well
known. One such system includes a tail which is articulatable
relative to the penetrator's housing. This system, however, is
limited since curvilinear motion could be effected only along one
fixed plane. Another type system in which the plane of the
articulatable tail can be controlled is disclosed in the
above-mentioned Southworth patent, in Reinold U.S. Pat. No.
3,480,098, and in Coyne U.S. Pat. No. 3,589,454. In these systems
the tail can be made to assume any desired planar attitude with
respect to the penetrator body. Finally, Coyne et al. U.S. Pat. No.
3,525,405 discloses a subterranean penetrator including a planar
beveled surface located at the front end of the penetrator housing
while Coyne et al. U.S. Pat. No. 3,620,295 discloses a steering
system including an articulatable tail having mounted thereon an
active fin or fins.
In spite of such numerous prior art steering systems, effecting a
practicable realization thereof has been difficult. For example,
some of these systems require complex and numerous parts, exotic
materials, excessive penetrator length and cross-sectional area,
and involved control algorithms. Other numerous problems relating
to the control dynamics of subterranean penetrators have also been
encountered.
Objects of this invention are therefore to:
a. provide a subterranean penetrator steering system which is
practically realizable;
b. reduce the weight, length, and complexity of a subterranean
penetrator including an associated steering system;
c. eliminate the need for an articulatable tail of any type and the
apparatus required to actuate such a tail;
d. provide steering capability equivalent to that of prior art
systems.
SUMMARY OF THE INVENTION
According to the present invention, a subterranean penetrator
steering system includes a fixed fin and a rotatable fin. The fixed
fin is attached to the exterior of the penetrator at a positive
angle with the penetrator's longitudinal axis. The rotatable fin is
located diametrically opposite to the fixed fin, the axis of
rotation thereof being perpendicular to and approximately
intersecting the penetrator's longitudinal axis. An associated
actuating mechanism located within the penetrator adjustably
orients the position of the rotatable fin. Curvilinear penetrator
motion along the desired steering plane is effected when the
rotatable fin is parallel to the fixed fin, the axis of rotation of
the rotatable fin being perpendicular to this plane. Forward
penetrator motion is effected by either of two modes, superimposed
penetrator rotation about its longitudinal axis simultaneously
occurring in either case.
According to the first forward mode, the rotatable fin is
antiparallel to the fixed fin. In other words, the rotatable fin
makes a negative angle with the penetrator's longitudinal axis
equal in magnitude to that made by the fixed fin.
According to a second forward mode, the actuating mechanism allows
the rotatable fin to be idle, in which case the fin automatically
assumes some lesser negative angle with respect to the penetrator's
longitudinal axis.
According to a specific embodiment of the invention, the fins are
located at the rear of the penetrator, the fixed fin making an
angle of approximately 25.degree. with the penetrator's
longitudinal axis.
According to a more specific embodiment of the invention, the rear
portion of the penetrator which houses the fins is inwardly tapered
at approximately 4.degree. to allow use of substantially smaller
fins and/or produce higher steering rates for a given length
penetrator. In this case, fins are advantageously located as far
back along the tapered portion as is physically possible.
Features of this invention are therefore that:
a. it utilizes a fixed or passive fin and a rotatable or active
fin;
b. the fins are located at the rear of the penetrator;
c. the fixed fin makes an angle of approximately 25.degree. with
the penetrator's longitudinal axis;
d. the angle made by the fixed fin with the penetrator's
longitudinal axis is limited by the slip angle of the soil;
e. the penetrator's rear portion including the fins is inwardly
tapered;
f. the taper angle at the penetrator's rear portion is
approximately 4.degree. ;
g. the rotatable fin's axis approximately intersects and is
perpendicular to the penetrator's longitudinal axis;
h. the fins are placed as far back along the tapered rear portion
as possible;
i. curvilinear penetrator motion along the desired steering plane
is effected when the rotatable fin is parallel to the fixed fin,
the axis of rotation of the rotatable fin being perpendicular to
this plane;
j. in the first forward mode penetrator motion is effected when the
rotatable fin is antiparallel to the fixed fin;
k. in another forward mode penetrator motion is effected when the
rotatable fin is idle, in which case it automatically assumes some
angle with respect to the penetrator's longitudinal axis;
l. the angle made by the fixed fin with the penetrator's
longitudinal axis is substantially greater than the taper angle at
the penetrator's rear portion;
m. the angle made by the fixed fin with the penetrator's
longitudinal axis and the small taper angle at the penetrator's
rear portion are both measured in the same direction relative to
the penetrator's longitudinal axis;
n. forward penetrator motion is accompanied by simultaneous
penetrator rotation about its longitudinal axis;
o. it utilizes a fixed fin and a rotatable fin of substantially
identical structure to effect both forward and curvilinear
penetrator motion;
p. one surface of the fixed fin exclusively makes contact with the
oncoming soil;
q. in one forward mode one surface of the rotatable fin exclusively
makes contact with the oncoming soil; and
r. in another forward mode both surfaces of the rotatable fin
simultaneously make contact with the oncoming soil.
Advantages of this invention are therefore that:
a. additional critical cross-sectional area is provided for the
passage of through hoses and electrical cables;
b. it requires fewer and simpler components than do prior art
steering systems;
c. the penetrator can be made lighter and its length smaller while
providing an equivalent turning radius to that of prior art
steering systems;
d. tapering the rear portion of the penetrator allows for smaller
fins and/or a smaller turning radius for a given length penetrator;
and
e. easier assembly and maintenance.
BRIEF DESCRIPTION OF THE DRAWING
The above and other objects, advantages, and features of the
present invention will be better appreciated by a consideration of
the following detailed description and the drawing in which:
FIG. 1A is an overall perspective view of a subterranean penetrator
in the steering mode, while FIGS. 1B and 1C are partial views of
the penetrator in each of two forward modes;
FIG. 2 is a detailed view showing the penetrator's rear portion
including the steering system of the present invention;
FIG. 3 is a detailed cross-sectional view showing the steering
system's actuating mechanism; and
FIG. 4 shows a graph and an associated outline of the penetrator
steering behavior.
DETAILED DESCRIPTION
FIG. 1A is an overall perspective view of a subterranean penetrator
and its associated steering system according to the present
invention. Subterranean penetrator 10 includes elongated
cylindrical housing 20, further including nose portion 30 and rear
portion 40. Subterranean penetrator 10 is located in a surrounding
soil medium, not shown. Central portion 21 of housing 20 includes a
hammer, not shown, which cyclically impacts an anvil, also not
shown, located within nose portion 30. Located behind this hammer
is a detection package, also not shown. Extending from the rear of
penetrator 10 is hose-cable combination 70 which carries both the
electrical information and the power required to properly execute
the propulsion, detection, and steering functions. The propulsion
and detection functions are not part of this invention and
therefore will not be further discussed herein.
According to the present invention, steering system 80, which in
this case is advantageously located on rear portion 40, further
includes fixed fin 50 and rotatable fin 60. These fins are of
substantially identical structure. Fixed fin 50 is attached to
housing 40 by a well-known mechanical means, not shown.
For explanatory purposes only, a right-handed coordinate system
including orthogonal axes X, Y and Z has been superimposed onto
rear portion 40 of subterranean penetrator 10. It is apparent that
the instantaneous forward direction and longitudinal axis O of
penetrator 10 coincide with the Y-axis while the rotation axis of
the rotatable fin 60 coincides with the positive X-axis. In FIGS.
1A, 1B, and 1C, the positive Z-axis is directed towards the top of
the page. The relative positions of fins 50 and 60 are such that
the negative X-axis intersects and passes through fixed fin 50.
According to this invention, fixed fin 50 makes a positive angle
.theta..sub.f, not shown in the figure, with the positive Y-axis.
Angle .theta..sub.f which is measured in a counterclockwise manner
from the positive Y direction when viewing along the negative X
direction, advantageously ranges between 25.degree. and 30.degree.
and has a practical upper limit determined by the soil slip
angle.
Fixed fin 50 and rotatable fin 60 respectively include upper
surfaces 51 and 61. In a similar manner, fins 50 and 60
respectively include lower surfaces 52 and 62, not designated in
FIG. 1. These latter surfaces are indicated in FIG. 2.
FIG. 2 is a detailed view showing rear portion 40 and associated
steering apparatus 80 according to the present invention. For
explanatory purposes, penetrator 10 has been rotated 90.degree.
about the Y-axis in a counterclockwise manner when viewing
penetrator 10 along the positive Y direction. In this case,
therefore, the positive X-axis is directed towards the top of the
page. The Y and Z axes are shown accordingly. Shown in this figure
are bottom cylindrical surface 42 of rear portion 40 and lower
surfaces 52 and 62 of fixed and rotatable fins 50 and 60. Rotatable
fin 60 is attached to its associated actuating mechanism at 53, as
will be further discussed hereinafter.
According to the present invention, curvilinear motion of
penetrator 10 along steering plane Y-Z is effected when rotatable
fin 60 is parallel to fixed fin 50. This is designated by position
S of rotatable fin 60. In the steering mode, therefore, lower
surfaces 52 and 62 of fins 50 and 60, respectively, make contact
with the oncoming soil to effect such curvilinear motion. In this
mode fin 60 has been rotated in a counterclockwise manner relative
to the positive Y-axis when looking along the negative X direction
by its associated actuating mechanism, not shown in this figure.
Fin 60 therefore makes a positive angle .theta..sub.r, not shown in
the figure, relative to the positive Y direction which is equal to
angle .theta..sub.f. It can be stated that the associated actuating
mechanism is active or energized. No rotation or slight rotation of
penetrator 10 about longitudnal axis O in the counterclockwise
direction when viewing along the positive Y direction accompanies
such curvilinear motion depending on system activation energy and
possible small differences in fin size. See also FIG. 1A.
According to a first forward mode, motion of penetrator 10 along
the positive Y direction is effected when rotatable fin 60 is
antiparallel to fixed fin 50. See position F1 of fin 60. In this
case, rotatable fin 60 makes a negative angle .theta..sub.r with
respect to the positive Y direction. Angle .theta..sub.r is equal
in magnitude to .theta..sub.f and again has an upper limit defined
by the soil slip angle. During this mode lower surface 52 of fixed
fin 50 and upper surface face 61 of rotatable fin 60 make contact
with the oncoming soil. Fin 60 has been rotated in a clockwise
direction relative to the positive Y-axis by its associated
actuating mechanism, not shown. Again, it can be stated that the
associated actuating mechanism is active or energized. Also during
this mode, uniform clockwise penetrator rotation at a rate R1
degrees/foot about its longitudinal axis O accompanies such forward
penetrator motion, when viewing along the positive Y direction.
Roll rate R1 is the result of the particular fin structure, fin
angle, etc. See also FIG. 1C.
According to a second forward mode, motion of penetrator 10 along
the positive Y direction is effected when rotatable fin 60 is
idle--i.e., when this fin is not activated or energized by its
associated mechanism. In this case, rotatable fin 60 automatically
assumes some negative angle relative to the positive Y direction.
See position F2 of rotatable fin 60. This, of course, is determined
by the particular fin structure, fin angle, etc. As will be
apparent to those skilled in the art, both upper and lower surfaces
61 and 62 of rotatable fin 60 make contact with the oncoming soil.
In this case, forward motion of penetrator 10 is accompanied by
uniform clockwise penetrator rotation at a rate R2 degrees/foot
about longitudinal axis O. Rate R2 is somewhat less than the rate
R1 mentioned above. Again, lower surface 52 of fixed fin 50 makes
contact with the oncoming soil. In this case, as opposed to the
steering and first forward modes, the actuating mechanism
associated with rotatable fin 60 is de-energized or deactivated as
will be further discussed with respect to FIG. 3. This second
forward mode therefore allows for a simpler actuating mechanism
having fewer components. This therefore results in more critical
cross-sectional area being made available for through hoses and
electrical cables which are necessary for the propulsion and
detection functions. See also FIG. 1B.
FIG. 3 is a detailed cross-sectional view showing the actuating
mechanism of steering system 80 used to adjustably orient rotatable
fin 60. Again, rear portion 40 is seen from below, in which case
the positive X-axis is directed towards the top of the page. As
stated before, rotatable fin 60 is attached to its associated
actuating mechanism at 53. Attached to rotatable fin 60 at 53 from
below is shaft member 54, the center of which coincides with the X
direction. Associated with shaft member 54 is lever arm member 55
which provides moment arms between the center of rotation of fin 60
and hydraulic cylinder members 56 and 58. A small hose, not shown,
provides actuating pressure to cylinder member 56. Actuation of
cylinder member 56 causes counterclockwise rotation of rotatable
fin 60 when viewed along the -X direction. This is effected during
the steering mode to make rotatable fin 60 parallel to fixed fin
60. A second small hose, also not shown, provides actuating
pressure to cylinder member 58. Actuation of cylinder member 58
causes clockwise rotation of fin 60 when viewed along -X direction.
This, of course, is effected during the first forward mode to make
rotatable fin 60 antiparallel to fixed fin 50.
It will be apparent to those skilled in the art that cylindrical
member 58, its associated small hose and lever arm portion, can be
eliminated. In such a case, only cylindrical member 56 is utilized
to actively rotate fin 60 until it is parallel to fixed fin 50,
this corresponding to the above-mentioned second forward mode.
Eliminating cylinder member 58 and its associated components
provides extra penetrator cross-sectional area for the through
hoses and cables leading to the detection and propulsion systems.
As mentioned before, rotatable fin 60 will automatically assume
some negative angle relative to the positive Y direction. Again,
the position assumed by rotatable fin 60 is always accompanied by
contact of both fin surfaces with the oncoming soil.
According to the present invention, upper cylindrical surface 41 of
rear portion 40 is inwardly tapered in such a manner that surface
41 makes a positive angle .theta..sub.t with the positive Y
direction. See FIG. 1B. Angle .theta..sub.t is advantageously
approximately 4 degrees. Having such a taper on rear portion 40 of
penetrator 10 eliminates contact of rear portion 40 with the tunnel
wall. Such taper allows for substantially improved steering when
compared with that provided by a penetrator of the same overall
length not having such a taper.
FIG. 4 shows a graph and an associated diagram which are
explanatory of steering system behavior. Note that the abscissa of
the graph and scale of the diagram correspond one to one. In FIG. 4
the abscissa is f/L.sub. p wherein f is the distance of the fins
from the front of the penetrator housing while L.sub.p is the
length of the penetrator housing, not including the tapered rear
portion. The length of the tapered rear portion is L.sub.t. The
ordinate, in turn, is R, the radius of curvature. The graph of FIG.
4 has been analytically derived assuming predetermined fin
parameters. It is apparent that steering of a subterranean
penetrator according to the present invention can be effected by
placing the fins at either the front or rear of the penetrator. It
so happens that very little or no steering results when the fins
are located along the central portion of the penetrator. If
R.sub.max is the maximum acceptable turning radius, then the fins
must be placed as indicated by the left and right shaded areas.
Further, appropriately placing the fins either on the front or the
rear results in approximately equivalent turning radii. However,
placing the fins on the front is difficult since the hoses would
have to lead thereto. In addition, the steering system would be
susceptible to unduly high impact stresses due to the impacting
anvil. According to the present invention, therefore, placement of
the fins along the rear of the penetrator is preferred.
The graph shows qualitatively that a significant reduction in
radius of curvature can be realized by locating the fins back on a
tapered housing.
While the subterranean penetrator steering system of the present
invention has been described in terms of specific embodiments, it
will be apparent to those skilled in the art that many
modifications are possible within the spirit and scope of the
disclosed principle.
* * * * *