EP0381726A4 - Skewed axis inertial sensor assembly - Google Patents
Skewed axis inertial sensor assemblyInfo
- Publication number
- EP0381726A4 EP0381726A4 EP19890908314 EP89908314A EP0381726A4 EP 0381726 A4 EP0381726 A4 EP 0381726A4 EP 19890908314 EP19890908314 EP 19890908314 EP 89908314 A EP89908314 A EP 89908314A EP 0381726 A4 EP0381726 A4 EP 0381726A4
- Authority
- EP
- European Patent Office
- Prior art keywords
- gyros
- accelerometers
- suspension
- plane
- base member
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C21/00—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00
- G01C21/10—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration
- G01C21/12—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration executed aboard the object being navigated; Dead reckoning
- G01C21/16—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
Definitions
- This invention pertains to a skewed axis inertial sensor assembly, to a gyro and accelerometer mounting base for a skewed axis inertial sensor assembly, and to a method of providing inertial reference.
- a redundant strapdown inertial navigation system utilizes two or three discrete inertial reference units.
- Each IRU includes a discrete inertial sensor apparatus (hereinafter referred to as "ISA") for producing sensor data, and associated electronics for signal processing and generating inertial reference data.
- ISA's generally include three discrete gyros and three discrete accelerometers for the production of necessary sensor data required by the IRU. All three gyros and all three accelerometers and their electronics must be operative in an ISA, as described, for each IRU of a redundant IRU system to produce complete inertial reference data.
- a three IRU redundant strapdown system just described requires in combination a total of nine gyros and nine accelerometers.
- This 3 IRU type of system is a "fail op/fe gyroscopes may be on the same side of the suspension plane provided that a counter balancing mass is made part of the base member 10 to cause the common centerpoint CCP to be the center of gravity.
- the base member is intended to be a unitary structure, it is also within the spirit and scope of the present invention that the base member may be a plurality of piece parts which have been fixed or bonded together to form a single structure, and that the sensor mountings are such that the input axis of the sensors meet the intended conditions.
- ring laser gyros have matured over recent years to yield excellent performing gyros.
- ring laser gyros have a need for a mechanical dither for rotationally oscillating the gyro such that the gyro avoids the so called lock-in condition.
- an IRU which mounts three gyros in an orthogonal configuration results in the input axes of these gyros to move in a cone shape due to cross coupling of the mechanical dither from one gyro to the other two gyros. It is therefore desirable to provide an inertial sensory assembly that reduces cross coupling between ring laser gyros.
- the sensor base member is provided with a plurality of suspension members for mounting the base member to a chassis.
- the base member is coupled to the chassis through a plurality of elastic members which have 5 elastic center-points which define a suspension plane.
- the base member, suspension members, and elastic members are arranged such that the suspension plane extends through the common centerpoint defined by the input axes of the gyros and the accelerometers, and in Q which the common centerpoint is preferably the center of gravity of the total suspended assembly.
- FIG. 1 is a top plan view of an inertial sensor assembly base member in accordance with the present invention.
- FIG. 2 is a projected elevational view taken from lines 2-2 of FIG. 1.
- FIG. 3 is an elevational sectional view through lines 3-3 of FIG. 1.
- FIG. 5 is a detail view of a suspension mount of Figure 1.
- FIG. 6 is a top plan view schematic of the sensor geometry of the ISA of FIG. 1.
- FIG. 7 is an elevational plan schematic of the sensor geometry of the ISA of FIG. 6 taken from lines 3-3 of FIG. 1.
- FIG. 8 is a top view of Figure 1 with gyro sensors attached.
- the inertial sensor assembly in accordance with the present invention includes a base member 10 for providing mounting surfaces for six gyros and six accelerometers (shown on subsequent drawings) .
- Figure 1 shows a top plan view of base member 10.
- Base member 10 is shown to be symmetrical about the X-axis, and more particularly about the X-Z plane (the Z-axis being out of the plane of the paper) .
- the base member 10 is preferably comprised of a block of a selected material, generally to provide high stiffness and light weight, for example Aluminum.
- Base member 10 includes an upper portion 12a and a lower portion 12b as defined by an imaginary suspension plane SP in parallel with the X-Y plane and passing through the common centerpoint CCP as will be subsequently described.
- the base member portion 12a includes five gyro mountings apertures 31-35 in the form of a ring around the Z-axis.
- the mounting apertures are constructed in body member 10 such that when the gyros are mounted, the extension of each input axis of each gyro passes through the common centerpoint CCP. Further, the angle is the same between the Z-reference-axis and the gyro. Lastly, the angle between the input axes of adjacent gyros are equal.
- Base member upper portion 12a also includes a sixth gyro mounting aperture 36 for mounting a sixth gyro such that its input axis is parallel with the
- the accelerometer input axis should preferably be as close to the center of gravity or center of mass of the base member.
- accelerometers are generally of smaller size than gyros (although not always) .
- the base member lower portion 12b is structurally smaller and allows closer proximity of the accelerometers to the common centerpoint CCP. The structural details are particularly illustrated in Figure 2 which shows a projected elevational view of Figure 1 taken from lines 2-2, Figure 3 which is an elevational view through lines 3-3, and Figure 4 which is a bottom plan view taken from lines 4-4.
- the lower portion 12b includes five accelerometer mounting apertures 41-45 in the form of a ring around the Z-axis.
- the mounting apertures 41-45 are constructed in base member 10 such that when the accelerometers (not shown) are mounted, the extension of the input axis of each accelerometer passes through the common centerpoint CCP. Further, the angle between the accelerometer input axis and the Z-axis of each accelerometer is the same. Lastly, the angle spherical between the input axes of adjacent accelerometers are equal.
- the spherical angle between the input axis of any one of accelerometers 41-45 and the Z-axis, and the spherical angle between the input axes of adjacent accelerometers is 63.4 degrees - the spherical angle between normals to faces of a dodecahedron.
- Lower portion 12b also includes a sixth accelerometer mounting aperture 46 for mounting a sixth accelerometer such that its input axis is aligned with the Z-reference-axis and also passes through CCP.
- the six accelerometers have an equal spherical angle between each other.
- the arrangement of mounting apertures for the gyros and accelerometers on base member 10 is such that the X-Z plane of symmetry is maintained.
- each of the gyros has its input axis co-linear with one accelerometer input axis, with the sensor pair being on opposite sides of the suspension plane SP.
- the six inertial reference axes are established.
- the six inertial reference axes are the six axes of a regular dodecahedron - each axis being the normal to two opposite faces of a regular dodecahedron.
- all sensor input axes are at a spherical angle of 63.4 degrees (one place accuracy) from each other.
- Suspension mounts 26 for the sensor assembly are particularly illustrated in Figure 1-8. Details of only one of four suspension mount assemblies 200 is illustrated in the Figures, the others not shown are configured in a similar manner.
- Sensor base member 10 is shown having four suspension mounts 26.
- the centerline 27 of each mount is in parallel with the Z-reference axis and is equidistant from the common centerpoint CCP.
- An elastic suspension member 28, well known in the art, is assembled between each suspension mount 26 and to chassis mounts 11.
- the elastic suspension member 28 and the suspension mount 26 are secured together by, for example a bolt 801 shown in Figure 8.
- Each elastic suspension member 28 includes, for example, a member 802 for being secured to chassis 11, thereby suspending the base member 10 through the elastic suspension member 28.
- the suspension mounts 26 are located on the same side, lower portion 12b of body member 10, as the accelerometer mounting apertures 41-46.
- the common centerpoint CCP be the same as the center of mass or center of gravity for the suspension mass comprised of the combination of the base member 10, and all of the gyros and accelerometers as mounted to base member 10, and the suspension mount assemblies.
- the common centerpoint of all the reference axes of the sensors is the same as the center of gravity of the system, and that the suspension plane SP passes through the center of gravity as well as the common centerpoint CCP of the reference axis.
- Gyros 131-136 have input axes which correspond to axes Ag, Bg, Cg, Dg, Eg and Zg respectively.
- accelerometers 141-146 have input axes corresponding to Aa, Ba, Ca, Da, Ea and Za respectively. Input axes Ag and Aa, Bg and Ba, Cg and Ca, Dg and Da, Eg and Ea, and Zg and Za all being co-linear.
- the base member 10 is constructed as aforesaid and illustrated herein such that six sensor pairs are established such that a sensor pair has one discrete accelerometer directly opposite the common centerpoint CCP from a respective gyro, and the input axes of the sensor-pair being co-linear.
- a portion of the geometric sensor structure of Figure 6 is shown in Figure 7 to show the sensor pair alignment.
- Each paired accelerometer input axis and gyro input axis lie upon and define a straight reference axis.
- Figure 8 illustrates base member 10 with gyros attached thereto. It also illustrates the four suspension mounts.
- a unitary base member structure which provides mounting for six gyros and six accelerometers in a specific configuration which allows for a set of six reference axis in which each reference axis has a sensor pair comprised of one accelerometer and one -?y ro having there respective input. xis being co-linear with each other.
- the planar surfaces on the block are geometrically configured such that normals to all of the surfaces can intersect at a common centerpoint.
- the base member mounting apertures in the block have been shown, all that is required is a mounting surface or means to secure the sensors to the base member.
- the base member having the apertures was utilized to achieve good dynamic stability by advantageous application of inertial moment considerations. Of course, variations in sensor configurations will effect the base member structure with out departing from the true spirit and scope of the present invention.
- the structure is of course within the scope of the present invention. Specifically, it was found that with an aluminum base member and a steel casing for an accelerometer, it was preferable to have the accelerometer held up away from the base member by pedestals 300 as illustrated in the Figures.
- the present invention is particularly suited for application of ring laser gyros in which the ring laser gyro includes a mechanical dither mechanism which oscillates the gyro relative to the case.
- the ring laser gyro includes a mechanical dither mechanism which oscillates the gyro relative to the case.
- the input axis tends to rotate in a conical pattern. This is attributed to cross coupling between the mechanical dithering mechanisms and the platform.
- the base member has been illustrated in a system requiring six gyros and six accelerometers, the base member may be modified, and within the spirit and scope of the present invention, to accommodate any plurality of gyros and accelerometers in which the input axis of the sensors meet at a common centerpoint and/or the common centerpoint is at the center of gravity. Specifically, the principles of the present invention are applicable to a triad of gyros and accelerometers.
- the accelerometers and the gyroscopes may be on the same side of the suspension plane provided that a counter balancing mass is made part of the base member 10 to cause the common centerpoint CCP to be the center of gravity.
- the base member is intended to be a unitary structure, it is also within the spirit and scope of the present invention that the base member may be a plurality of piece parts which have been fixed or bonded together to form a single structure, and that the sensor mountings are such that the input axis of the sensors meet the intended conditions.
Landscapes
- Engineering & Computer Science (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Automation & Control Theory (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Gyroscopes (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US19951088A | 1988-05-27 | 1988-05-27 | |
US199510 | 1998-11-25 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0381726A1 EP0381726A1 (en) | 1990-08-16 |
EP0381726A4 true EP0381726A4 (en) | 1992-08-19 |
Family
ID=22737835
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19890908314 Withdrawn EP0381726A4 (en) | 1988-05-27 | 1989-05-23 | Skewed axis inertial sensor assembly |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0381726A4 (en) |
JP (1) | JPH03501526A (en) |
WO (1) | WO1989011632A1 (en) |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6340137B1 (en) * | 1998-08-26 | 2002-01-22 | Honeywell International Inc. | Moment control unit for spacecraft attitude control |
US8234943B2 (en) * | 2002-03-01 | 2012-08-07 | Ganid Productions, Llc | Apparatus and method for gyroscopic propulsion |
US7121159B2 (en) * | 2002-03-01 | 2006-10-17 | Ganid Productions, Llc | Apparatus and method for gyroscopic propulsion |
SE528404C2 (en) | 2004-10-20 | 2006-11-07 | Imego Ab | The sensor arrangement |
CN107588764B (en) * | 2017-08-07 | 2020-02-11 | 北京航天时代光电科技有限公司 | Optical fiber gyroscope assembly for four-axis redundant configuration power supply and circuit board cold backup |
CN108267156B (en) * | 2017-12-20 | 2020-03-24 | 北京航天时代激光导航技术有限责任公司 | Method for determining gyroscope jitter performance of laser inertial measurement unit structure system |
CN109238280B (en) * | 2018-09-29 | 2021-04-13 | 北京航天时代激光导航技术有限责任公司 | Aviation miniaturized inertial navigation part adopting 50 type laser gyro |
Family Cites Families (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3269179A (en) * | 1959-05-29 | 1966-08-30 | Honeywell Regulator Co | Navigational instruments |
US3403874A (en) * | 1965-07-20 | 1968-10-01 | Honeywell Inc | Control apparatus for aircraft having fail-safe monitoring gyros |
US3489004A (en) * | 1966-07-21 | 1970-01-13 | Honeywell Inc | Navigational reference device |
US3463909A (en) * | 1966-08-15 | 1969-08-26 | Singer General Precision | Vector sensing system |
US4020702A (en) * | 1974-06-17 | 1977-05-03 | The Bendix Corporation | Redundant inertial measurement system configuration |
US4179818A (en) * | 1976-10-07 | 1979-12-25 | Litton Systems, Inc. | Tetrahedral redundant inertial reference unit |
US4125017A (en) * | 1977-07-29 | 1978-11-14 | Mcdonnell Douglas Corporation | Redundant inertial measurement system |
US4212443A (en) * | 1978-05-18 | 1980-07-15 | Sperry Corporation | Strapped down attitude and heading reference system for aircraft employing skewed axis two-degree-of-freedom rate gyros |
US4675820A (en) * | 1984-06-14 | 1987-06-23 | Sundstrand Data Control, Inc. | Inertial reference system |
US4711125A (en) * | 1985-11-06 | 1987-12-08 | Morrison Melvin M | Inertial measurement unit |
US4795258A (en) * | 1987-04-06 | 1989-01-03 | Litton Systems, Inc. | Nonplanar three-axis ring laser gyro with shared mirror faces |
US4825716A (en) * | 1987-11-13 | 1989-05-02 | Honeywell, Inc. | Single gimbal control moment gyroscope skewed array mounting arrangement |
-
1989
- 1989-05-23 JP JP1507973A patent/JPH03501526A/en active Pending
- 1989-05-23 WO PCT/US1989/002221 patent/WO1989011632A1/en not_active Application Discontinuation
- 1989-05-23 EP EP19890908314 patent/EP0381726A4/en not_active Withdrawn
Non-Patent Citations (1)
Title |
---|
No further relevant documents have been disclosed. * |
Also Published As
Publication number | Publication date |
---|---|
EP0381726A1 (en) | 1990-08-16 |
JPH03501526A (en) | 1991-04-04 |
WO1989011632A1 (en) | 1989-11-30 |
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