US 4,321,678 A · Apparatus for the automatic determination of a vehicle position

Abstract

The position of a vehicle is derived from vehicle speed and heading. A two-axis electrically restrained gyro, the spin axis of which is parallel to the vehicle vertical axis, serves at first to determine the north direction with stationary vehicle. The attitude of the vehicle about the longitudinal and transverse axes is measured by means of a pair of vehicle-fixed accelerometers. True north direction is derived from the signals of the accelerometers and of the gyro. Subsequently the gyro is rotated through 90.degree. about one input axis and serves as heading-attitude reference during the mission. The rotary speed about a third axis perpendicular to the input axes of the gyro is measured by means of a rotary acceleration meter the output of which is applied to an integrator. During the mission, the attitude parameters of the vehicle are computed continuously from the initial attitude parameters and the rotary speeds. An estimated value of the gyro drift is obtained in a filter by comparison with a magnetic heading and is taken into account. The speed signal from a vehicle speed sensor and inertial speed signals which are derived from the acceleration signals are applied to a filter which provides an estimated value of the error of the speed signal. The speed signal is corrected for this estimated value. The corrected speed signal is resolved into components in accordance with the attitude parameters. The position of the vehicle is derived from these speed components by integration.

Claims25

Dependent claims

Navigational instrument for a vehicle, wherein the north direction is determined by means of a gyro, comprising:

a two-axis gyro having a spin axis, a first and a second input axis,
a first angle pick-off and a first torquer on the first input axis,
a second angle pick-off and a second torquer on the second input axis,
first amplifier means for applying the amplified angle signal from the first angle pick-off to the second torquer, second amplifier means for applying the amplified angle signal from the second angle pick-off to the first torquer, and
signal processing means, to which the amplified angle signals are applied,
characterized in that:
(a) the gyro with the angle pick-offs and the torquers is arranged in an intermediate housing,
(b) the intermediate housing is mounted for rotation about an axis of rotation parallel to one input axis through 90.degree. from a first position with substantially vertical spin axis into a second position,
(c) a pair of vehicle-fixed accelerometers is arranged with its input axes parallel to the transverse and longitudinal axes, respectively, of the vehicle, said accelerometers producing accelerometer signals A.sub.x.sup.F, A.sub.y.sup.F respectively,
(d) the signal processing means comprise
(d.sub.1) first computer means for providing initial vehicle attitude signals from the amplified angle signals with stationary vehicle and said first position of the intermediate housing, and
(d.sub.2) second computer means for continuously providing vehicle attitude signals representing the attitude of the moving vehicle in an earth-fixed coordinate system from said initial vehicle attitude signals, said angle signals from the angle pick-offs and said accelerometer signals with the second position of the intermediate housing.

9 more elements

Heading-attitude reference unit for determining the heading and the attitude of a vehicle, comprising:

rotary speed sensor means, which are arranged to respond to the rotary speeds about three mutually perpendicular, vehicle-fixed input axes, said means including at least two rotary speed sensors producing sensor signals, two accelerometers having vehicle-fixed, mutually perpendicular input axes which respectively are parallel to the input axes of the two rotary speed sensors, said accelerometers producing sensor signals, and computer means, to which the signals from the rotary speed sensors and from the accelerometers are supplied for providing signals representing transformation parameters between a vehicle-fixed coordinate system and an earth fixed coordinate system, as well as the heading angle in the earth-fixed coordinate system, said computer means comprising
(a) means for receiving said sensor signals and providing signals
(4) C.sub.31 =C.sub.32 .omega..sub.z.sup.F -C.sub.33 .omega..sub.y.sup.F
(5) C.sub.32 =C.sub.33 .omega..sub.x.sup.F -C.sub.31 .omega..sub.z.sup.F
wherein
C.sub.31,C.sub.32,C.sub.33 are the elements of the last line of the directional cosine matrix,
C.sub.31,C.sub.32 are the associated time derivatives,
.omega..sub.x.sup.F is the rotary speed about an input axis x.sup.F in the vehicle-fixed coordinate system,
.omega..sub.y.sup.F is the rotary speed about the second input axis y.sup.F in the vehicle-fixed coordinate system, and
.omega..sub.z.sup.F is the rotary speed about the third input axis z.sup.F in the vehicle-fixed coordinate system,
(b) means connected to receive the signals C.sub.31 and C.sub.32 and integrate the received signals with respect to time to provide signals C.sub.31 and C.sub.32, respectively,
(c) means connected to receive the signals C.sub.31 and C.sub.32 from the integration means and for producing a signal ##EQU44## (d) from the signal C.sub.31 and C.sub.32 thus obtained, means connected to feed the signals C.sub.31,C.sub.32 and C.sub.33 back to the computer for providing C.sub.31 and C.sub.32 from the rotary speed signals,
(e) means connected to receive the signals C.sub.31,C.sub.32 and C.sub.33 and the rotary speed signals .omega..sub.z.sup.F and .omega..sub.y.sup.F and for producing a signal ##EQU45## therefrom, and (f) means connected to receive this signal .psi..sub.I and integrating it with respect to time to provide a signal .psi..sub.I representing the heading angle in the earth-fixed coordinate system.

10 more elements

Instrument for the automatic determination of the north direction by means of a gyro affected by the rotation of the earth, wherein

the gyro is a two-axis gyro the spin axis of which is substantially vertical,
the position of the gyro is picked off by position pick-offs and torquer is arranged to exert erecting torques on the gyro to keep the spin axis of the gyro vertical,
a position pick-off and a torquer is provided on each of two mutually perpendicular input axes of the gyro,
the signal from each position pick-off associated with one input axis is supplied crosswise to the torquer on the respective input axis to restrain the spin axis of the gyro to the vertical, and
the signal supplied to the two torquers are, at the same time, applied to a north deviation computer, which provides, from the ratio of the signals, a signal representing the deviation of an instrument-fixed reference direction from north,
characterized in that
(a) the north deviation computer comprises a memory for storing the two signals T.sub.y.sup.(1), T.sub.x.sup.(1) supplied to the torquers,
(b) the gyro is arranged to be rotated through 180.degree. about a horizontal axis by a servomotor, after the signals have been stored,
(c) the signals T.sub.y.sup.(2), T.sub.x.sup.(2) then supplied to the torquers are supplied to the north deviation computer,
(d) the north deviation computer comprises means for providing signals
.DELTA.T.sub.y =T.sub.y.sup.(1) -T.sub.y.sup.(2) ( 8)
.SIGMA.T.sub.x =T.sub.x.sup.(1) +T.sub.x.sup.(2) ( 9)
wherein ##EQU46## M.sub.x.sup.(1) and M.sub.x.sup.(2) are the stored signals and the signals applied after the 180.degree.-rotation to that torquer, which acts about one axis,
M.sub.y.sup.(1) and M.sub.y.sup.(2) are the stored signals and the signals applied after the 180.degree.-rotation to the other torquer, and
H is the rotary momentum of the gyro, and
(e) the north deviation computer comprises means for providing a signal ##EQU47## as north deviation signal.

13 more elements

Instrument for the automatic determination of the north direction by means of a gyro affected by the rotation of the earth, wherein

the gyro is a two-axis gyro the spin axis of which is substantially vertical,
the position of the gyro is picked off by position pick-offs and a torquer is arranged to exert erecting torquers on the gyro ot keep the spin axis of the gyro vertical,
a position pick-off and a torquer is provided on each of two mutually perpendicular input axes of the gyro,
the signal from each position pick-off associated with one input axis is supplied crosswise to the torquer on the respective input axis to restrain the spin axis of the gyro to the vertical, and
the signals supplied to the two torquers are, at the same time, applied to a north deviation computer, which provides, from the ratio of the signals, a signal representing the deviation of an instrument-fixed reference direction from north,
characterized in that
(a) the north deviating computer comprises a memory for storing the two signals T.sub.y.sup.(1), T.sub.x.sup.(1) supplied to the torquers,
(b) the gyro is arranged to be rotated by a servomotor through 180.degree. about a vertical axis coinciding with the gyro spin axis, after these signals T.sub.x.sup.(1), T.sub.y.sup.(1) have been stored,
(c) the signals T.sub.x.sup.(3), T.sub.y.sup.(3) then supplied to the torquers are applied to the north deviataion computer,
(d) the north deviation computer comprises means for providing signals
DT.sub.x =T.sub.x.sup.(1) -T.sub.x.sup.(3) ( 15)
DT.sub.y =T.sub.y.sup.(3) -T.sub.y.sup.(1) ( 16)
wherein ##EQU48## M.sub.x.sup.(1) and M.sub.x.sup.(3) are the stored signals and the signals applied to one torquer, after the 180.degree.-rotation,
M.sub.y.sup.(1) and M.sub.y.sup.(2) are the stored signal and the signals applied to the other torquer after the 180.degree. rotation, and
H is the rotary momentum of the gyro, and
(e) the north deviation computer comprises means for providing a signal ##EQU49## as north deviation signal.

13 more elements

Instrument for the automatic determination of the north direction by means of a gyro affected by the rotation of the earth, wherein the gyro is a two-axis gyro the spin axis of which is substantially vertical,

the position of the gyro is picked off by position pick-offs and a torquer is arranged to exert erecting torques on the gyro to keep the spin axis of the gyro vertical,
a position pick-off and a torquer is provided on each of two mutually perpendicular input axes of the gyro, the signal from each position pick-off associated with one input axis is supplied crosswise to the torquer on the respective input axis to restrain the spin axis of the gyro to the vertical, and
the signals supplied to the two torquers are, at the same time, applied to a north deviation computer, which provides, from the ratio of the signals, a signal representing the deviation of an instrument-fixed reference direction from north,
characterized in that
(a) the north deviation computer comprises a memory for storing the two signals T.sub.y.sup.(1), T.sub.x.sup.(1) supplied to the torquers,
(b) the gyro is arranged to be rotated by a first servomotor through 180.degree. about a vertical axis coinciding with the gyro spin axis, after these signals T.sub.x.sup.(1), T.sub.y.sup.(1) have been stored
(c) the north deviation computer comprises a memory for storing the two signals T.sub.x.sup.(3), T.sub.y.sup.(3) then supplied to the torquers,
(d) the first servomotor is controlled to rotate the gyro housing through 180.degree. back into the initial position, after these latter signals have been stored,
(e) the gyro is arranged to be rotated by a second servomotor through 180.degree. about a horizontal input axis, after it has been rotated back by the first servomotor,
(f) the signals T.sub.x.sup.(2), T.sub.y.sup.(2) then supplied to the torquers are applied to the north deviation computer,
(g) the north deviation computer comprises means for providing signals
.SIGMA.T.sub.xc =T.sub.x.sup.(2) -T.sub.x.sup.(3) ( 22)
.DELTA.T.sub.y =T.sub.y.sup.(1) -T.sub.y.sup.(2) ( 23)
wherein
T.sub.x.sup.(2) is the signal which, after rotation of the gyro about said one input axis y, is applied to that torquer which acts on the other input axis,
T.sub.x.sup.(3) is the signal which, after rotation of the gyro about the vertical axis, is supplied to that torquer which acts on said other input axis,
T.sub.y.sup.(1) is the signal which, in the initial position prior to the rotation about the vertical axis, is supplied to that torquer which acts about said one input axis,
T.sub.y.sup.(2) is the signal which, after the rotation about the horizontal axis, is supplied to that torquer which acts on said one input axis, and
(h) the north deviation computer comprises means for providing a signal ##EQU50## as north deviation signal.

16 more elements

An instrument for the automatic determination of the north direction by means of a gyroscope affected by the rotation of the earth and having a spin axis, said instrument having an instrument-fixed reference direction and being characterized by:

gyroscope positioning means secured to said gyroscope and mounting said gyroscope for pivotal movement about two input axes at right angles to each other, said positioning means positioning said spin axis substantially vertical, said positioning means including first and second torquers associated with said input axes respectively for controlling the angular position of the spin axis about the input axes respectively, first and second pickups associated with said input axes respectively for producing signals indicative of the angular position of the spin axis about the input axes respectively, and control means including said pickups and said torquers for actuating the torquer associated with one axis in response to the signal from the pickup associated with the other axis and for actuating the torquer associated with said other axis in response to the signal from the pickup associated with said one axis;
and a north direction computer, connected to said control means to receive said signals, for producing from the ratio of the signals a north deviation signal indicative of the deviation from north of the instrument-fixed reference direction, said north deviation computer providing a signal ##EQU51## wherein U.sub.x is the voltage which is supplied to the one torquer acting about the one input axis of the gyroscope,
K.sub.Tx is the constant of said one torquer,
U.sub.y is the voltage which is supplied to the other torquer acting about the other input axis of the gyroscope, and
K.sub.Ty is the constant of said other torquer,
said north deviation computer comprising a quadrant logic circuit for determining the quadrant of the north deviation, said quadrant logic circuit being connected to receive the two signals supplied to the torquers, and a quadrant computer, to which the signal ##EQU52## is applied together with an output signal from the quadrant logic circuit and which provides a north deviation signal .psi. taking the quadrant of the north deviation into consideration.

3 more elements

gyroscope positioning means secured to said gyroscope and mounting said gyroscope for pivotal movement about two input axes at right angles to each other, said positioning means positioning said spin axis substantially vertical, said positioning means including first and second torquers associated with said input axes respectively for controlling the angular position of the spin axis about the input axes respectively, first and second pickups associated with said input axes respectively for producing signals indicative of the angular position of the spin axis about the input axes respectively, and control means including said pickups and said torquers for actuating the torquer associated with one axis in response to the signal from the pickup associated with the other axis and for actuating the torquer associated with said other axis in response to the signal from the pickup associated with said one axis;
a north direction computer, connected to said control means to receive said signals, for producing from the ratio of the signals a north deviation signal indicative of the deviation from north of the instrument-fixed reference direction;
accelerometer means operatively associated with the gyroscope for providing a pair of error signals indicative of the deviation of the gyroscope spin axis from the vertical, the accelerometer means comprising a pair of accelerometers mounted in a fixed orientation with respect to the vehicle, said accelerometers having axes of sensitivity which are perpendicular to each other and respectively parallel to the two input axes of the gyroscope;
the gyroscope being rotatable through 90.degree. about one of the input axes of the gyroscope between the position at which the spin axis is vertical and a position at which the spin axis is horizontal;
and including a computer for computing the true heading of the vehicle from the information provided by the accelerometers about the attitude of the vehicle relative to a horizontal plane, and from the angular speed about the vehicle-fixed input axes of the gyroscope provided by the gyroscope.

2 more elements

Navigational instrument for a land vehicle having a fixed longitudinal axis x, a fixed transverse axis y and a fixed vertical axis z, said instrument comprising:

an inertial measuring unit producing inertial speed signals and having rotation-responsive inertial sensors, which respond to rotary movements about said axes and have known drifts d.sub.x, d.sub.y, d.sub.z about their longitudinal, transverse and vertical axes x, y and z respectively, and accelerometers, which respond to linear accelerations along vehicle-fixed axes, the accelerometer sensitive in the direction of the longitudinal axis x producing a signal A.sub.x.sup.F and having a known deviation b.sub.x,
a speed sensor having a scale factor, which speed sensor responds to the speed of the vehicle with respect to ground in the direction of the longitudinal axis of the vehicle and produces a speed singal v.sub.x.sup.F in the direction of the vehicle longitudinal axis,
a transformation parameter computer connected to receive the signals from the inertial measuring unit and which comprises means for computing transformation parameters for the transformation of vector components from a vehicle-fixed coordinate system into an earth-fixed coordinate system,
corrective signal generators connected to receive the accelerometer signals and the transformation parameters from the transformation parameter computer and which provide signals representing the components due to gravity of the accelerations detected by the accelerometers, said gravity component signals being superposed to the signals from the accelerometers to provide translation acceleration signals,
integrators connected to receive the translation acceleration signals to produce inertial speed signals v.sub.Ix.sup.F and v.sub.Iy.sup.F, an optimal filter connected to receive the inertial speed signals and the speed signals from the speed sensor and which, on the basis of these signals, produces estimated speed signals .DELTA.v.sub.Ix.sup.F and .DELTA.v.sub.Iy.sup.F referenced to vehicle-fixed coordinates v.sub.Ix.sup.F and v.sub.Iy.sup.F,
a coordinate transformation computer connected to receive the estimated speed signals and the transformation parameters from the transformation parameter computer and which comprises first means for transforming these speed signals into transformed speed signals, which are referenced to an earth-fixed coordinate system, said computer producing signals C.sub.31, C.sub.32, C.sub.33 from the last line of a directional cosine matrix for the transformation from a vehicle-fixed coordinate system into an earth-fixed coordinate system, and
a position computer connected to receive the transformed speed signals and which comprises second means for providing position signals representing the position of the vehicle,
said optimal filter comprising:
(a) a first summing point connected to receive the estimated value .DELTA.v.sub.Ix.sup.F of the error of the longitudinal component signal v.sub.Ix.sup.F of the inertial speed and the estimated value .DELTA.v.sub.x.sup.F of the error of the speed signal v.sub.x.sup.F and to produce a difference signal therefrom,
(b) a second summing point connected to receive the inertial speed signal v.sub.Ix.sup.F and the speed sensor speed signal v.sub.x.sup.F and to produce a difference signal v.sub.Ix.sup.F -v.sub.x.sup.F therefrom.
(c) a third summing point connected to receive said two difference signals and to produce a third difference signal z.sub.1 therefrom,
(d) a fourth summing point connected to receive the inertial speed signal v.sub.Iy.sup.F and the estimated value .DELTA.v.sub.y.sup.F of the error of the transverse component signal v.sub.Iy.sup.F of the inertial speed and to provide a fourth difference signal z.sub.2 therefrom,
(e) a first multiplier connected to receive the difference signal z.sub.1 and to multiply it by a given factor K.sub.11 to produce a signal K.sub.11 z.sub.1,
(f) third means connected to receive signals d.sub.z, d.sub.y from the inertial measuring unit and signals C.sub.32, C.sub.33 from the coordinate transformation computer and to produce a signal C.sub.32 d.sub.z -C.sub.33 d.sub.y therefrom,
(g) a fifth summing point connected to said third means and said first multiplier to produce a signal representing the sum of the signals from said third means and the first multiplier,
(h) a first integrator connected to said fifth summing point to integrate said sum of said signals and thereby produce a signal .DELTA.C.sub.31 which represents an estimated value of the error of the signal C.sub.31 of the directional cosine matrix,
(i) a second multiplier connected to receive the difference signal z.sub.2 and to multiply it by a given factor K.sub.22 to produce a signal K.sub.22 z.sub.2,
(j) fourth means connected to receive signals d.sub.x, d.sub.y from the inertial measuring unit and signals C.sub.31, C.sub.33 from the coordinate transformation computer and to produce a signal C.sub.33 d.sub.x -C.sub.31 d.sub.y therefrom,
(k) a sixth summing point connected to said fourth means and said second multiplier to produce a signal representing the sum of the signals from the fourth means and the second multiplier,
(l) a second integrator connected to said sixth summing point to integrate the sum signal of the sixth summing point and thereby produce a signal .DELTA.C.sub.32 which represents an estimated value of the error of the signal C.sub.32 of the directional cosine matrix,
(m) multiplying means connected to receive signals C.sub.31 and z.sub.1 and to multiply the signal C.sub.31 by the accelerating due to gravity and to multiply the signal z.sub.1 by a given factor K.sub.31 and by the known accelerator deviation b.sub.x to produce output signals gC.sub.31 and K.sub.31 z.sub.1 b.sub.x,
(n) a seventh summing point connected to said multiplying means to receive the output signals therefrom and to add those signals together to produce a sum signal,
(o) a third integrator connected to said seventh summing point to receive the sum signal therefrom and to integrate it to produce a signal .DELTA.v.sub.Ix.sup.F representing the estimated value of the error of the longitudinal component signal v.sub.Ix.sup.F of the inertial speed,
(p) an eighth summing point connected to receive the signals A.sub.x.sup.F and gC.sub.31 and add them to produce a signal v.sub.x.sup.F representing the translatory acceleration in the direction of the longitudinal axis of the vehicle,
(q) multiplying means and a fourth integrator connected to receive the difference signal z.sub.1 multiply it by a given factor K.sub.61 and integrate the product K.sub.61 z.sub.1 thereof to produce a signal .DELTA.k.sub.x representing the estimated value of the error of the scale factor of the speed sensor,
(r) multiplying means and a ninth summing point connected to receive the difference signal z.sub.1 and the translatory acceleration signal v.sub.x.sup.F, to multiply the difference signal z.sub.1 with a given factor K.sub.51 and to add the product K.sub.51 z.sub.1 thereof with the signal v.sub.x.sup.F to produce an output signal,
(s) a sixth integrator connected to receive and integrate the last mentioned output signal to produce a signal .DELTA.v.sub.x.sup.F which represents the estimated value of the error of the speed signal from the speed sensor,
(t) multiplying means connected to receive the signals C.sub.32 and z.sub.2, to multiply the signal C.sub.32 by the acceleration g due to gravity and to multiply the signal z.sub.2 by a given factor K.sub.42 and by the known zero deviation b.sub.x to produce output signals gC.sub.32 and K.sub.42 z.sub.1 b.sub.x,
(u) a tenth summing point connected to receive the output signals of the last mentioned multiplying means and to add those signals together to produce a sum signal,
(v) a seventh integrator connected to receive the sum signal from the tenth summing point and to integrate that signal to produce a signal .DELTA.v.sub.Iy.sup.F which represents the estimated value of the error of the transverse component signal v.sub.Iy.sup.F, and
(w) means connected to receive the speed signal v.sub.x.sup.F and the estimated speed error signal .DELTA.v.sub.x.sup.F and to subtract the latter from the former to produce a corrected speed signal.

28 more elements

Dependencies are inferred from the claim text.

Apparatus for the automatic determination of a vehicle position

Life of this patent

Apparatus for the automatic determination of a vehicle position

Life of this patent

Abstract

Claims25