FR2531208A2 - IMPROVEMENTS IN GYROSCOPIC NAVIGATION FACILITIES - Google Patents

Abstract

THE INSTALLATION INCLUDES A SINGLE DRIVE SHAFT 1 MOUNTED ON THE VEHICLE AROUND THE LONGITUDINAL AXLE 2 OF THIS VEHICLE. THIS CARDAN INCLUDES A GYROSCOPE WITH TWO AXES OF SENSITIVITY G AND AN ACCELEROMETRIC BLOCK SLACED TO, ALSO WITH TWO AXES OF SENSITIVITY. THE TWO AZIMUT POSITION DETECTORS OF THE GYROSCOPE G LOCK THE AZIMUT PRECESSION TORQUE MOTOR OF THIS GYROSCOPE AND GIVE A GYROMETRIC MEASUREMENT. THE TWO ROLL POSITION DETECTORS OF THE GYROSCOPE G ENABLE THE ROLL ENCLOSURE MOTOR M OF THE CARDAN 1.

Description

Improvements to gyroscopic navigation installations

  The purpose of this certificate of addition is to

  certain provisions which are the subject of the main patent application N o 81 17692 filed on 18

  September 1981, with the aim of installing

  gyroscopic navigation techniques to understand the parameters characterizing the trajectory

of a vehicle.

  Among the provisions of this patent application,

  one of them was specifically aimed at

  gyroscopic navigation for a vehicle with virtually zero pitch dynamics, and

linear constant.

  It is this provision that this certificate of addition proposes to perfect, by adding to it

variants of embodiment.

  According to the present invention, the installation comprises a cardan mounted journalling on the vehicle around the longitudinal axis of the vehicle, a gyro with two axes of sensitivity mounted on it.

  cardan, so that one of its two axes of sensi-

  bility (axis of sensitivity in azimuth) is orthogonal

  the longitudinal axis of the vehicle, the other axis of

  the sensitivity of this gyroscope (axis of sensitivity in roll) being parallel to the longitudinal axis of the vehicle, and

  so that the axis of rotation of its top is now

  held in a horizontal plane, and an accelerometer block controlled by at least two sensitivity axes mounted on this gimbal, so that, for two of them, one of its two axes (axis of sensitivity in azimuth) is parallel to the axis of sensitivity in azimuth of the gyroscope, and that the other axis of sensitivity (axis of sensitivity in roll)

  parallel to the axis of rotation of the gyroscope.

  This being the case, these elements cooperate with each other in the following way: 2- the azimuth position detectors of the gyroscope slave the precession torque motor in azimuth of the gyroscope and give an indication which is exploited to obtain the azimuth parameters characterizing the trajectory the vehicle (angular velocity n Z); the roll position sensors of the gyro slave the servo motor in roll of the gimbal; this drives the stator of an angular position sensor in roll;

  the roll tilt signal SAX of the acceleration

  rometer is used to level, by precession, the axis of rotation of the gyroscope (which causes a

  slow rotation of the cardan around the axis of sensi-

  roll rate of the gyroscope), and the inclination signal S Az of the accelerometer (a signal which, in the short term, has a noise) indicates, in the long term <if it is filtered), pitching

  of the vehicle, or the slope of the trajectory followed.

  According to a variant of this provision, the block

  accelerometer has three axes of sensi-

bility, namely:

  an axis of sensitivity parallel to the axis of sensi-

  the azimuth of the gyroscope, an axis of sensitivity in roll parallel to the axis of rotation of the gyroscope, and a pitch sensitivity axis parallel to the longitudinal axis of the vehicle, thanks to which it is possible to carry out a

  good measure of the slope, even if one describes a

  jectory almost horizontal (which brings a

  to the above provision which does not allow

did not put such a measure).

  Under these conditions, the pitch inclination signal S Ay of the accelerometer further indicates, at

  long-term, the pitch of the vehicle.

  It should also be noted that, when the longitudinal axis of the vehicle is almost vertical -3- and the vehicle stopped and locked, the installation then behaves, thanks to the arrangement of the axes of sensitivity of the gyroscope and the accelerometer block,

  as a northern research facility composed of

  linked (possibility of bringing the axis of sensitivity of the gyroscope near the East-West line, which gives a good measure of the inclination of the axis of rotation of the gyroscope and its axis of sensitivity in roll, measurement necessary for projection corrections of the Earth's rotation vector on the axis of

  roll sensitivity of the gyroscope).

  The invention, according to this certificate of addi-

  Therefore, it applies more particularly in the case of gyroscopic navigation systems for vehicles of the type of underground or submarine drilling exploration probes such as oil drilling. The invention will be better understood by means of

  additional description which follows as well as

  drawings attached, which complement and drawings relate to a preferred embodiment of the invention and do not include, of course, no

limiting character.

  FIG. 1 of these drawings illustrates the diagram of a borehole in which an exploration probe

  can be descended in order to know the characteristics

  geometric data of this drilling.

  Fig. 2 is a schematic perspective view showing the constituent elements of the installation

according to the invention.

  FIG 3 is a schematic perspective view showing the constituent elements of the installation

according to a variant of the invention.

  FIGS. 4 and 5 are respectively two diagrams showing how the elements constituting the installation shown in FIGS. 2 and 3 co-operate with each other; FIG. 1 shows the diagram of a borehole starting from a point I on the surface, next

  first of all, on a portion I II, a recom-

  vertical tilt, then, on a portion II III, a curved path, and, finally, sweat a portion III IV,

  a rectilinear or slightly curved path whose

  vertical, can reach and even more (this path may even be horizontal) In Part III IV, the principle of azimuth navigation functions as described in

the main patent application.

  According to the invention, the installation comprises (Figures 2 and 3):

  a single cardan 1 mounted journaling, through

  level 5, on the vehicle around the axis

  longitudinal axis 2 of the vehicle, said gimbal being

  of a roll control motor My and an angular position sensor roll Py a gyroscope with two axes of sensitivity G mounted on it

  cardan 1, so that one of its two axes of sensi-

  bility (azimuth sensitivity axis Gz) is orthogonal to the axis 2 of the vehicle, the other sensitivity axis (axis of sensitivity Gy roll) being parallel to the longitudinal axis 2 of the vehicle, and so that the rotation axis SG of its router is maintained in a horizontal plane, and an accelerometer block controlled by at least two sensitivity axes mounted on this universal joint 1, de -sorte that one of its two axes (axis of sensitivity in azimuth Az) is parallel to the sensitivity axis

  in azimuth G of the gyroscope G, and the other axis of sensibility

  the axis of sensitivity in roll Ax) is parallel to the axis of rotation SG of the gyroscope G. In FIG. 4, the gyroscope has been shown twice.

  G, in two cuts respectively carried out

  perpendicular to its axis of sensitivity in azimuth Gz and perpendicular to its axis of sensitivity in

Gy roll.

  This gyroscope G comprises a router 7 carried by a shaft 8 by means of a Hoocke seal 9,

  this shaft 8 being maintained by bearings 10.

  The position of the spindle 7 is controlled by two DG Zl azimuth position detectors by two DGY roll position detectors by an MGV azimuth precession torque motor 1

  and by a precession torque motor in roll -MGY.

  The two azimuth position detectors DGZ of the

  gyroscope G enslaving, via a

  positive electronic signal 16 ensuring in particular the alternating amplifier then demodulator function, the motor of azimuth precession torque MGZ of the gyroscope G. These two azimuth position detectors DGZ always give, via the electronic device 16, the gyrometric measurement z which It is used in an azimuth measuring device 170 The two roll position sensors D of the GY gyroscope G slave, via a

  electronic device 20 ensuring in particular the function

  alternator and then demodulator, the

  servo motor in roll M cardan l.

  The servo motor M mechanically drives the position sensor Py roll of the gimbal 1 which

  gives the angle of roll which is exploited in a

roll measuring instrument 21.

  The roll tilt signal SA of the access

  lerometer A, filtered by the low-pass filter FPB, is sent in slow precession on the MGY roll precession torque motor of the gyroscope G to level its axis of rotation SG and to maintain the universal joint 1 regardless of the angular movements

of the vehicle.

  The inclination signal S Az of the accelerometer A is filtered and indicates the pitch of the vehicle (Ta) c necessary for the precession Qztg (Ta) c of the gyroscope G along its axis of sensitivity in roll Gy (value

broadband).

  In FIG. 5, accelerometer A has been shown in FIG.

  a cut by a plane containing its two axes of sensi-

  This accelerometer comprises a controlled mass 15 whose position is controlled by two position detectors DAZ, by two roll position detectors DAX,

  and by two servo windings EAX and EAZ.

  According to the variant illustrated in FIG.

  accelerated accelerometer: A has three axes of sen-

eligibility, namely:

  an axis of sensitivity Az parallel to the axis of sensi-

  Gz azimuth capacitance of the gyroscope G, a roll sensitivity axis AX parallel to the rotation axis S of the gyroscope G, and a pitch sensitivity axis Ay parallel to

the longitudinal axis 2 of the vehicle.

  The SAZ tilt signal of such an accelerated block

  rometer A gives the calculated pitch (Ta) c of the vehicle,

  and the pitch pitch signal S Ay of the accelerating block

  In the case of redundancy, A gives the pitch of the vehicle

  cule (sensitivity in vertibal or horizontal drilling ensured). In the portions I II and II III of the borehole, where the axis of the vehicle is quasivertical, the installation

  behaves then, during the continuous descent of

  hicle, as a directional installation, the axis

  rotation of the gyroscope not being leveled.

  Many navigation processes are then envi-

  sizable in these portions; however, the method of first finding the North (stopped vehicle), and then rotating the axis of rotation of the gyroscope in azimuth of an angle (measured on the angular position sensor roll P y) such that the axis of rotation of the gyroscope is approximately perpendicular to the mean vertical plane which contains at best the portions II and II III (for example the point III may be the one where the inclination of the bore with respect to the horizontal - 7-

is 15).

  In this way, points I to III of the

  drill hole, the axis of rotation of the gyroscope "geometrically bound to the gimbal" will tilt only slightly (of a value less than or equal to 1) and the

  horizontal projection of the axis of rotation of the gyros

  cope will rotate little in azimuth, 'despite the precession of the gyro in azimuth which is lower

or equal to 0.2.

  Thanks to this situation, the transition to a

  "directional rotation with gyro rotation

  level III, and as

  written about fig 4, will be facilitated.

-8-

Claims (4)

  1. Gyro mounted navigation installation   on a vehicle and allowing to know the parameters   very characterizing the trajectory of this vehicle,   characterized by the fact that it comprises, in   boring, the following elements: a cardan (1) mounted journalling on the vehicle around the longitudinal axis (2) of the vehicle, a gyroscope with two axes of sensitivity (G) mounted on this gimbal (1), so that the one of its sensitivity axes (axis of sensitivity in azimuth Gz) is orthogonal to the longitudinal axis (2) of the vehicle, the other   axis of sensitivity of this gyroscope (G) (axis of sensi-   roll Gy) being parallel to the longitudinal axis   nal (2) of the vehicle, and that the axis of rotation (SG) of its router (7) is maintained in a horizontal plane, and a slave accelerometer block (A) to at least two axes of sensitivity mounted on it gimbal (1), so that one of its two axes (sensitivity axis Az) is parallel to the axis of azimuth sensitivity (Gz) of the gyroscope (G), and the other axis of sensitivity (axis of sensitivity roll AX) is parallel to the axis of rotation (SG) of the gyroscope (G), and in that these elements cooperate with each other in the following manner   azimuth position detectors (DGZ) of the gyro-   scope (G) enslave the motor precession torque in azimuth (MGZ), and give an indication that is   exploited to obtain the characteristic azimuth parameters   stabilizing the trajectory of the vehicle (angular velocity IZ);   roll position sensors (D GY) of the gyro-   scope (G) controls the servo motor in   roll (My) of the cardan (1) which carries the stator of a   angular position sensor in roll (Py);   the roll tilt signal (SA) of the   lerometer (A) is used to precede the axis of rotation (SG) of the gyro (G) to -9 cause a slow rotation of the gimbal (1) around the axis of sensitivity in roll (Gy) gyroscope (G);   and the inclination signal (S Az) of the access   lerometer (A) is filtered to indicate the pitch of the vehicle.   2. Installation according to claim 1, characterized   characterized in that the accelerometer block (A) has three sensitivity axes, namely a sensitivity axis (Az) parallel to the azimuth sensitivity axis (Gz) of the gyroscope (G); a roll sensitivity axis (Ax) parallel to the axis of rotation (SG) of the gyroscope (G); and a pitch sensitivity axis (Ay) parallel   at the longitudinal axis (2) of the vehicle; -   the pitch inclination signal (S Ay) of the accelerometer (A) then indicating, in addition, pitching of the vehicle.   3. Installation according to claim 1 or 2,   characterized by the fact that the installation is opera-   as a North-linked component search facility when the longitudinal axis (2) of the vehicle is   vertical and the vehicle stopped and locked to the ground.   4. Installation according to claim 3, characterized in that at the end of the North search, the axis of rotation (SG) of the gyroscope (G) is wedged in a quasi-horizontal position, perpendicularly   the assumed vertical average plane of the curve of the   the vehicle, and then the vehicle picks up   its movement keeping its known azimuth.