US3664200A

US3664200A - Stable base mounts

Info

Publication number: US3664200A
Application number: US32700A
Authority: US
Inventors: Hendrik Ter Brugge
Original assignee: Thales Nederland BV
Current assignee: Thales Nederland BV
Priority date: 1969-05-08
Filing date: 1970-04-28
Publication date: 1972-05-23
Anticipated expiration: 1989-05-23
Also published as: SE363898B; FI49941B; GB1260617A; NL6907029A; CH508197A; DE2020405A1; FI49941C; BE750073A; NL156645B

Abstract

In a ship-born stable base mount is a hollow column secured in a position perpendicular to the deck plane of the ship. Means are presented for mounting a Gimbal system including two orthogonal axes on the upper end portion and a gyroscopically controlled servo drive system on the lower end portion of the hollow column. Furthermore, the stable base mount comprises transmission means controlled by the servo drive system and extending through the length of the interior of the hollow column to act on a base member to be stabilized.

Description

[451 May 23,1972

United States Patent Ter Brugge 1,964,869 7/1934 Boykow..................................74/5.22

[54] STABLE BASE MOUNTS 3,218,015 11/1965 Baer [72] Inventor: Hendrik Ter Brugge, l-lengelo, Nether-' lands FOREIGN PATENTS OR APPLICATIONS Great Britain........,.................74/5.22

Primary Examiner-Manuel A. Antonakas Attorney-Frank R. Trifari [22] Filed:

[21] Appl. No.: 32,700

ABSTRACT 1n a ship-bom stable base mount is a hollow column secured in [30] Foreign Application Priority Data May 8, 1969 a position perpendicular to the deck plane of the ship. Means Netherlands..........................6907029 are presented f mounting a Gimba] Sysmm including two orthogonal axes on the upper end portion and a gyroscopically controlled servo drive system on the lower end portion of the [52] US. 74/5.8, 114/122 [51] Int. ..,.G0lc 19/46 hollow column. Furthermore, the stable base mount com- 5s FieldofSearch..

prises transmission means controlled by the servo drive system and extending through the length of the interior of the hollow column to act on a base member to be stabilized.

l 1 Claims, 3 Drawing Figures References Cited UNITED STATES PATENTS 1,639,233 Paxton..............................,...74/5.6 X

PATENTEDMM 23 I972 3, 664,200

sum 1 or 3 INVENTOR H. TER BRUGGE PATENTEBmzsmn I 3.664.200

SHEET 2 OF 3 INVENTOR H. TER BRUGGE AGENT PATENTEDMAY 2 3 1912 SHEEI 3 BF 3 INVENTOR H. TER BRUGGE BY ifiwag,

AGENT STABLE BASE MOUNTS The invention relates to stable base mounts of the type comprising a gimbal system including two orthogonal axes, a base member and a gyroscopically controlled servo drive system for stabilizing said base member about said two orthogonal axes.

Such stable base mounts are known and find application aboard ships. The two orthogonal axes are most conveniently named roll axis and pitch axis respectively; the roll axis lies in a fixed position parallel to the fore and aft line of the ship and supports the pitch axis, which is in parallel to the earth surface.

The base member may constitute or carry a train axis, which may support an elevation axis, thus extending the arrangement to a three or four axes stable base mount. Having no train accelerations due to tilt of the deck and requiring no computers, such three or four axes stable base mounts are particularly suitable for mounting a radar antenna or other sighting means, such as for instance a television camera and/or infrared camera, especially when these sighting means have to perform at high rotational speeds as required in searching and/or tracking operations. Their applicability to stabilization problems is, however, severely limited by the mechanical difficulties encountered. These difficulties arise from the fact that separate servo drives are needed for controlling the rotation about each one of the different axes. As a result the known stable base mounts are relatively massive and suffer from top-heaviness.

It is an object of the present invention to provide a stable base mount in which the above mentioned difficulties have been substantially overcome.

According to the invention a shipbome stable base mount of the type comprising a gimbal system including two orthogonal axes, a base member and a gyroscopically controlled servo drive system for stabilizing said base member about said two orthogonal axes, is provided with a hollow column secured in a position perpendicular to the deck plane, means for mounting said gimbal system on the upper end portion and said servo drive system on the lower'end portion of said hollow column, and transmission means controlled by said servo drive system and extending through the length of the interior of said hollow column to act on said base member to be stabilized.

Other objects, advantages and novel features of the invention will become apparent from the following detailed description, when considered in conjunction with the accompanying drawings, wherein FIG. 1 is a perspective view showing in detail the base member to be stabilized and the manner in which it is suspended;

FIG. 2 is an over-all perspective view of the stable base mount according to the invention; and

FIG. 3 is a perspective view of a preferred embodiment of the servo drive system.

In these figures, like reference numerals denote like parts.

In the following description reference is made to sets of identical parts, even if only one part of such a set is actually visible in the relevant figure. However, since the arrangement shown is symmetrical with respect to two orthogonal axes, it will be understood, that the other part of such a set is present in a position symmetrically opposite said visible one.

Referring to FIG. 1, reference numeral 1 designates a base member to be stabilized about two orthogonal axes, i.e. a roll axis 2 and a pitch axis 3. To this end, there is provided a gimbal system comprising a set of identical supports, such as 4, and a gimbal ring 5 having a first set of identical hollow shafts, such as 6 and a second set of identical hollow shafts, such as 7. Both sets of shafts are rigidly connected to said gimbal ring 5 to constitute the said roll and pitch axes respectively. The first set of shafts constituting the roll axis is rotatably mounted in the supports 4 which are rigid with respect to, for instance, the deck plane of a ship. The second set of shafts constituting the pitch axis is mounted in bearings of base member 1, so as to permit said base member to rotate about these shafts. As may be seen in the figure, base member 1 is hollow and has a cyclindrical portion which extends in the vertical when said base member is stabilized. This cylindrical portion, therefore, may be used directly as a train axis or may carry a platform onto which any type of sighting means may be mounted for rotation about a train axis and an elevation axis.

Base member 1 is held in a given fixed position with respect to a stable reference. The stable reference is provided by

gyroscopes

8 and 9, the respective housings of which are secured in the interior of hollow shafts 6 and 7 respectively, as may be seen in the figure. The two gyroscopes have two degrees of freedom. Gyroscope 8 has a spin axis in the horizontal plane and is orientated in a given direction (for example North); it is therefore termed the azimuth or directional gyroscope, which supplies synchro-data used, inter alia, for calculating corrections required in view of deviations in azimuth owing to yawning of the ship. Since the gyroscope 8 does not play a direct part in the stabilization of base member 1, it will be left out of consideration here. Gyroscope 9 has a spin axis which by means of the conventional gyroscopic control means is held in an accurately vertical position. This gyroscope, which is termed vertical gyroscope, supplies at its two outputs 10 and 11, formed by synchros (not shown), two error voltages, the magnitude and sign of which are a measure of the deviation of base member 1 from the zero position as determined by the vertical spin axis of the gyroscope. These error voltages are supplied through respective servo amplifiers (not shown), to a servo drive system 12 (FIG. 3) to be described hereinafter. This servo drive system, when properly energized, is capable of tilting the base member to be stabilized about the hollow shafts 6 and 7, so that these error voltages are reduced to their zero value.

A favorable and particularly advantageous stable base mount is obtained in that,as shown in the figures, there is provided a hollow column 13 secured in a position perpendicular to the deck plane, means 14 for mounting said gimbal system on the upper end portion and said servo drive system 12 (FIG. 3) on the lower end portion of said hollow column and trans mission means 15 controlled by said servo drive system 12 and extending through the length of the interior of said hollow column to act on said base member to be stabilized.

In the preferred embodiment, hollow column 13 is of cylindrical shape except for its lower end portion, which is secured to a delta-shaped box 16 enclosing the servo drive system 12. This box is secured to the deck, preferably by means of shock absorbers (not shown) supporting said box at its three corners.

By mounting the servo drive system in box 16 on the lower end portion of hollow column 13, instead of mounting it directly onto the gimbal system, the weight and size of the gimbal system is materially reduced and hence, the center of gravity will be lower down. Owing to this, hollow column 13 as well as the said shock absorbers may be less heavy. At the same time the shock absorbers can be closer together as their relative spacing will be determined mainly by the size of box 16. Hence, a saving of valuable deck space is obtained. Moreover, owing to the reduced massiveness of the gimbal system, the latter may be realized in a manner permitting its total enclosure. To this end, as shown in FIG. 1, the set of supports 4 are mounted on a top-plate 14 of column 13 and in a position such that the point of intersection of roll axis 2 and pitch axis 3 is on the longitudinal axis 17 of hollow column 13. The set of shafts constituting the roll axis 2 and the set of shafts constituting the roll axis 2 and the set of shafts constituting the pitch axis 3 are both rigidly connected to the gimbal ring 5, so that they project inwardly therefrom; the outer diameter of said gimbal ring being slightly smaller than the outer diameter of hollow column 13. Base member 1 is provided with a circular cover plate 18 fixedly connected thereto and having a circular hole at its center, through which the cylindrical portion of base member 1 protrudes. The outer diameter of cover plate 18 is chosen to be equal to the outer diameter of hollow column 13. The gimbal system is enclosed by said circular cover plate 18 and a rubber bellows 19, the end portions of which are tightly fitted around the outer circumference of cover plate 18 and hollow column 13, by means of clamp rings 20 and 21 respectively.

In the preferred embodiment of the stable base mount thus far described, use is made of a servo drive system as illustrated in FIG. 3.

Referring thereto, reference numeral 22 designates a frame to be stabilized about two orthogonal axes, i.e. an associated roll axis 23 and pitch axis 24. To this end, the stable base mount is provided with a second gimbal system comprising a set of

supports

25, 26 and a gimbal frame 27. Frame 22 and gimbal frame 27 are each provided with a set of hollow shafts, such as 28 and 29 respectively. Each set of hollow shafts is rigidly connected to the relevant frame and projects outwardly therefrom to constitute the roll and pitch axes 23 and 24 respectively. The set of shafts constituting the roll axis 23 is rotatably mounted in the set of

supports

25, 26 so as to permit gimbal frame 27 to rotate with respect to said supports. These supports are rigidly secured to the inside top wall of box 16 in FIG. 2 and in a position such that the central axis 17 of hollow column 13 passes not only through the point of intersection of roll axis 2 and pitch axis 3, but also through the point of intersection of roll axis 23 and pitch axis 24; roll axis 2 and roll axis 23 being in parallel to one another. Gimbal frame 27 is further provided with a gear segment 30 which is fixedly connected to said gimbal frame. This gear segment is partially enclosed by a gear box 31 constituting the lower portion of support 25. Gear box 31 comprises a schematically presented gear train 32 and a reversible electric motor 33, which may apply a rotational movement to gimbal frame 27 by driving gear segment 30 via said gear train 32 in the one or in the other sense. The maximum angle through which gimbal frame 27 may rotate with respect to said supports is limited by stops, such as 34 and 35. These stops are on the outside back wall of the

supports

25, 26 and in a position symmetrical with respect to the roll axis 23. They cooperate with a member 36 which is fixedly connected to one end of a torsion bar 37 extending centrally through the length of said hollow shaft 28. The other end of said torsion bar is rigidly connected to gimbal frame 27, so that member 36 rotates with gimbal frame 27. The moment said member 36 meets a stop, torsion bar 37 operates as a shock-reducing resilient means.

The sets of shafts constituting the pitch axis 24 is rotatably mounted in bearings of gimbal frame 27, so as to permit frame 22 to rotate with respect to said gimbal frame. Frame 22 is provided with a gear segment 38 which is fixedly connected to said frame 22. Gear segment 38 is partially enclosed by a gear box 39 forming part of gimbal frame 27. Gear box 39 comprises a schematically presented gear train 40 and a reversible electric motor 41 which may apply a rotational movement to frame 22 by driving gear segment 38 via gear train 40 in the one or in the other sense. The maximum angle through which frame 22 may rotate with respect to gimbal frame 27 is limited by steps such as 42 and 43. These stops are on the outside of gimbal frame 27 and in a position symmetrical with respect to pitch axis 24. They co-operate with portions, such as 44, 45, projecting from a cover 46. The latter is fixedly connected to one end of a torsion bar 47 extending centrally through the length of hollow shaft 29. The other end of this torsion bar is rigidly connected to frame 22, so that cover 46 and its projecting portion 44, 45 rotate with frame 22. The moment said projecting portions meet a stop, torsion bar 47 operates as a shock-reducing resilient means.

Frame 22 and base member 1 are linked to one another in a manner such that the cylindrical portion of base member 1 will be in the vertical position when frame 24 is in the horizontal one. To this end, use is made of mechanical transmission means 15 which extend through the length of the interior of hollow column 13. In the embodiment shown these transmission means are constituted by four identical connecting rods. Frame 22 is provided with four shafts such as 48 and 49 which are disposed in parallel to the roll axis 23 and in positions symmetrical with respect to the roll and pitch

axis

23 and 24 respectively. Likewise base member 1 in FIG. 1 is provided with four shafts, such as 50, which are disposed in parallel to the roll axis 2 and in positions symmetrical with respect to the roll and pitch axes 2 and 3 respectively. The relative spacing of the four shafts in frame 22 is equal to the relative spacing of the four shafts of base member 1, so that each one of the four shafts in frame 22 may be said to form a pair with one of the four shafts of base member 1. The shafts of each pair are interconnected by one of the four connecting rods 15. In connecting these rods to the shafts use is made of spherical bearings such as 51 in FIG. 1 and 52 in FIG. 3, providing two degrees of freedom of motion. Since these connecting rods extend through the length of the interior of hollow column 13, the great advantage is obtained that, with the exception of the protruding cylindrical portion of base member 1, all moving parts of the stable base mount are totally enclosed.

Another advantage of the stable base mount here described is that even if hollow column 13 is bent, which may happen under adverse conditions, this will not affect the angular position of base member 1, owing to the fact that the identical connecting rods will remain in parallel at all times.

Assuming frame 22 in the horizontal position, the cylindrical portion of base member 1 will be in the vertical. Any roll and pitch angles applied to the deck plane will be measured by the vertical gyroscope 9 and corresponding error voltages occur at its outputs 10 and 11. These error voltages are applied to control

reversible motors

33 and 41 respectively, which tilt frame 22 and hence base member 1 to reduce these error voltages to their zero value.

In the embodiment described use is made of four connecting rods 15, it will be clear, however, that a smaller number of connecting rods may suffice.

In the embodiment described, the gyroscope housings are directly connected to the base member to be stabilized. This construction, although advantageous, is not essential, as it is also possible to arrange the gyroscopes at a distance remote from the base member to be stabilized, for example in the meta-center of the ship. It is also possible to slave the stabilization system to another stable base.

Finally, it may be observed that the stable base mount disclosed herein, is not limited to the use of the servo drive system as shown and described with reference to FIG. 3. Other types of servo drive systems, such as for instance a hydraulic servo drive system, can be used as well.

What we claim is:

1. A ship-born stable base mount, comprising a hollow column secured in a position perpendicular to a deck plane of the ship, a base member, means for mounting a gimbal system including two orthogonal axes on the top of the hollow column in a position such that the point of intersection of the orthogonal axes lies on the logitudinal axis of the hollow column, a gyroscopically controlled servo drive system mounted on the lower end portion of the hollow column for stabilizing the base member about the two orthogonal axes, and mechanical transmission means controlled by the servo drive system and extending through the length of the interior of the hollow column said transmission means acting on said base member whereby said bore member is stabilized about said two orthogonal axes.

2. A stable base mount as claimed in claim 1, wherein said gimbal system comprises a gimbal ring having two sets of hollow shafts projecting inwardly therefrom .to constitute a roll and pitch axis respectively.

3. A stable base mount as claimed in claim 2, wherein one of the hollow shafts constituting the pitch axis accomodates a vertical gyroscope producing error voltages which in magnitude and sense correspond to the deviation of said base member from the zero position as determined by said vertical gyroscope.

4. A stable base mount as claimed in claim 1, wherein said hollow column is of circular cross section and wherein the outer diameter of said gimbal ring is slightly smaller than the outer diameter of said hollow column.

5. A stable base mount as claimed in claim 1, wherein said base member comprises a cylindrical portion which extends in the vertical when said base member is stabilized.

6. A stable base mount as claimed in claim 1, wherein said base member is provided with a circular cover plate fixedly connected thereto and having a central hole through which the cylindrical portion of said base member protrudes.

7. A stable base mount as claimed in claim 6, wherein the outer diameter of said cover plate and the outer diameter of said hollow column are equal and wherein the gimbal system is totally enclosed by means of said cover plate and a bellows the end portions of which are tightly fitted around the outer circumference of said cover plate and the upper position of said hollow column.

8. A stable base mount as claimed in claim 1, wherein the lower end portion of said hollow column is secured to a box enclosing said servo drive system.

9. A stable base mount as claimed in claims 1, wherein said servo drive system comprises a frame suspended by a second gimbal system having orthogonal axes, said second gimbal system being mounted in said box in a manner such that the point of intersection of said orthogonal axis is lying on the longitudinal axis of said hollow column.

10. A stable base mount as claimed in claim 9, wherein said frame is stabilized about said orthogonal axis by means of direct gearing from electric motors to which the roll and pitch error voltages are applied.

11. A stable base mount as claimed in claim 1, wherein said transmission means are constituted by a number of connecting rods linking said stabilized frame to said base member in a manner such that the cylindrical portion of said base member extends in the vertical when said frame is in the horizontal position.

Claims

2. A stable base mount as claimed in claim 1, wherein said gimbal system comprises a gimbal ring having two sets of hollow shafts projecting inwardly therefrom to constitute a roll and pitch axis respectively.