METHOD AND APPARATUS FOR DETERMINING THE POSITION OF A VEHICLE

• US 3,849,636 A
• Filed: 03/07/1973
• Issued: 11/19/1974
• Est. Priority Date: 03/08/1972
• Status: Expired due to Term

• Current Assignee: Horst Helms
• Original Assignee: Horst Helms
• Inventors: Helms, Horst
• Primary Examiner(s): Gruber, Felix D.
• Application Number:
  US05/338,823
• Time in Patent Office: 622 Days
• Field of Search: 235/150.2,150.27,150.271 33/318,326
• US Class Current: 701/300
• CPC Class Codes: G01C 19/38 with north-seeking action by other than magnetic means, e.g. gyrocompasses using earth's rotation
• CPC Class Codes: G01C 21/188 for accumulated errors, e.g. by coupling inertial systems with absolute positioning systems

Abstract

A method of determining the momentary position of a vehicle using a north-seeking gyrocompass for obtaining a direction indication in the longitudinal direction with respect to geographic north, by developing representations of movement components in the longitudinal and transverse directions of the vehicle and supplying data representing the position of the vehicle based on any known starting point. These representations are used to develop a new position determination, the steps of the method being cyclically repeated. The method can be performed using a measuring device and a settable data input device which supplies signals representative of any starting point. Signals from the gyrocompass, the measuring device and the input device are supplied to signal processing circuits which include, as the output member of the apparatus, a summing circuit having two outputs on which appear, respectively, signals representative of the longitude and latitude at which the vehicle is momentarily positioned.

Claims

1. In apparatus to be mounted on a vehicle for producing signals indicative of the position of the vehicle relative to a known starting position, which apparatus includes:

means for developing successive signals representing components of the motion of the vehicle in longitudinal and transverse directions during successive intervals;

north-seeking gyrocompass means for producing a north direction indication signal;

data input means for supplying signals indicative of such known starting position of the vehicle; and

navigational computer means for producing signals indicative of the momentary position of the vehicle for each of the successive signals representing vehicle motion components, said computer constituting means for processing trigonometric functions and having first input means coupled to said means for developing successive signals representing vehicle motion components for receiving such signals and second input means coupled to said data input means for receiving signals indicative of the known starting position of the vehicle, the improvement wherein;

said navigational computer means comprises;

a. calculating circuit means connected to said first input means for receiving the successive signals representing vehicle motion components and for producing therefrom signals representing the resulting speed of the vehicle at such successive intervals;

b. speed angle circuit means connected to said first input means for receiving the successive signals representing vehicle motion components and for producing therefrom signals representing the speed angle of the vehicle at such successive intervals;

c. a logic circuit having first and second inputs, with said first input being connected to said calculating circuit means to receive the signals produced thereby and said second input being arranged to receive a signal indicative of the true directional angle of the vehicle movement, said logic circuit having first and second outputs and constituting means for deriving, from the signals at its inputs, a signal at its first output representative of the vehicle path component in the east/west direction and a signal at its second output representative of the vehicle path component in the north/south direction;

d. a summing circuit having first inputs connected to said second input means of said navigational computer means for receiving the signals supplied by said data input means, and second inputs connected to the first and second outputs of said logic circuit for receiving the signals produced thereby, said summing circuit having output means at which appear signals indicative of at least one component of the present position of the vehicle; and

said apparatus further comprises;

system error angle computer means having a first input coupled to said gyrocompass means for receiving the signal produced thereby, a second input connected to the output of said calculating circuit means to receive the signals produced thereby, a third input connected to the output of said speed angle circuit means to receive the signals produced thereby and a fourth input connected to said output means of said summing circuit to receive the signals appearing at such output, said system error angle computer constituting means for operating according to known gyrophysical motion equations in order to derive, from the signals supplied to its inputs, output signals representing the system error angle associated with said gyrocompass means;

addition circuit means having a first input connected to said gyrocompass means for receiving the signal produced thereby, a second input connected to said system error angle computer meAns for receiving the output signals produced thereby, and a third input connected to said speed angle circuit means for receiving the signals produced thereby, said addition circuit means combining the signals at its said inputs to produce at its output a signal indicative of the true directional angle of the vehicle movement, the output of said addition circuit means being connected to the second input of said logic circuit.

2. An apparatus as defined in claim 1 wherein said speed angle circuit means includes:

a quotient former having its two inputs respectively connected to outputs of said means for developing motion representing components; and

a calculating circuit coupled to said quotient former and responsive to signals therefrom, said calculating circuit constituting an arc tangent function generator, the signal being furnished from the output of said speed angle circuit means being the momentary speed angle signal.

3. An apparatus as defined in claim 1 wherein said means for developing motion representing components has two outputs, and said calculating circuit means constitutes means for forming a geometric sum and includes one output and two inputs, each of said inputs being connected to a respective one of said outputs of said means for developing motion representing components, the signals representative of the momentary resulting speed of the vehicle appearing at said output of said calculating circuit means.

4. An apparatus as defined in claim 1 wherein said means for developing motion representing components includes an output for a speed representing component in the transverse direction of said vehicle, and said calculating circuit means, which forms the signals representative of the resulting speed, includes a quotient former, having first and second inputs and an output, and a trigonometric computing circuit constituting a sine function generator, said trigonometric computing circuit being connected at its input to the output of said speed angle circuit means and at its output to said first input of said quotient former, said second input of said quotient former being connected to said output for the speed representing component in the transverse direction.

5. An apparatus as defined in claim 1 wherein said means for developing motion representing components includes an output for a speed representing component in the longitudinal direction of the vehicle, and said calculating circuit means includes a quotient former having first and second inputs and an output, and a trigonometric computing circuit constituting a cosine function generator, said trigonometric computing circuit being connected at its input to the output of said speed angle circuit means and at the output to said first input of said quotient former, said second input of said quotient former being connected to said output for the speed representing component in the longitudinal direction.

6. An apparatus as defined in claim 1 wherein said summing circuit of said navigational computer means produces geographic latitude representing signals at its said output means and said system error angle computer means includes:

summation circuit means for forming a first auxiliary parameter, said summation circuit means being connected at its input to the output from the speed angle circuit means and to the output from said gyrocompass;

a computer circuit means for forming the course error as the first system error angle, and having a first input connected to the output of said summation circuit means, a second input connected to said output means of said summing circuit in said navigational computer means for the geographic latitude representing signals, and a third input connected to the output of said calculating circuit means;

adder means for forming a second auxiliary parameter and having an input connected to the output of said summation circuit means and the output from said computer circuit means;

speed former circuit means for forming the speed representations in he aPproximate north direction and in the approximate east direction and having two inputs connected respectively to the output of said adder means and the output of said calculating circuit means;

a partial computer means having two inputs directly connected respectively to two outputs of said speed former circuit means and having two further inputs indirectly connected to said two outputs of said speed former circuit means, via a difference value circuit, and having a last input connected to the output of said summing circuit in said navigational computer means, said partial computer having outputs at which appear representations of the azimuthal system error angle, the speed angle and the north direction indication of said gyrocompass and which together define the true directional angle; and

a difference comparator having a first input connected to the output of said partial computer which provides the azimuthal system error angle, and a second input connected to the output of said computer circuit means, the output of said difference comparator being connected to further input of said summation circuit means to form the first auxiliary parameter.

7. An apparatus as defined in claim 6 wherein said computer circuit means is a delta device for developing the course error as the first system error angle.

8. An apparatus as defined in claim 6 wherein said computer circuit means comprises a ratio former having two inputs, a factor former, divider circuit means, and an arc sine function circuit, and wherein the first input of said computer circuit means includes a computer circuit constituting a cosine function generator and whose output is connected to one input of said ratio former;

the second input of said computer circuit means includes a computing circuit constituting a cosine function generator and connected at its output to said factor former, which calculates the peripheral speed of the earth for the position of the vehicle as a product of the rotational speed and radius of the earth, which are fixed factors in said factor former, and the cosine of the geographic latitude; and

the output of said factor former and a third input of said computer circuit means are connected to two inputs of said divider circuit means whose divisor is the resulting speed of the vehicle and whose dividend is the peripheral speed of the earth, the output of said divider circuit means being connected to the other input of said ratio former, to which is connected in series said arc sine function circuit, the course error being obtained as the first system error angle at the output of said function circuit.

9. An apparatus as defined in claim 6 wherein said speed former circuit means includes:

at its first input for the second auxiliary parameter, a computer circuit constituting a cosine function generator, and a computer circuit constituting a sine function generator;

a first multiplying circuit having one input connected to the output of said first computer circuit and a second multiplying circuit having one input connected to the output of said second computer circuit, the second input of said speed former circuit means constituting the second input of both said multiplying circuits and being connected to the output of said calculating circuit means, the speeds of the vehicle being obtained in the approximate north direction and in the approximate east direction at the respective outputs of said speed former circuit, these being constituted, respectively, by the outputs of said multiplying circuits.

10. An apparatus as defined in claim 9 wherein said means for developing motion representing components comprise:

acceleration former circuit means structurally identical to said speed former circuit means;

an additional calculating circuit means; and

accelerometer means, and wherein said partial computer means is connected at its input to the outputs of said speed former circuit means to receive signals indicative of the speeds in the approximate north and east directions and additionaLly to the outputs of said acceleration former circuit means, one input of said acceleration former circuit means is connected to the output of said adder means to receive a signal therefrom representative of the second auxiliary parameter and another of its inputs is connected to an output of said additional calculating circuit means, and the inputs of said additional calculating circuit means are connected to receive the acceleration components in the longitudinal and transverse directions of the vehicle to form a signal representative of the resulting acceleration of the vehicle.

11. An apparatus as defined in claim 6, wherein said difference value circuit includes:

a delay means producing a time delay corresponding to a set time interval; and

two identical circuits, each comprising a scanner which scans, at a given rate each cycle of which is equal to the set time interval, the momentary speeds at the respective outputs of said speed former circuit; and

a difference former circuit which is connected respectively at one of its inputs directly to said scanner and at the other of its inputs, via said delay means, to a respective one of the outputs of said speed former circuit, the accelerations in the approximate north and east directions of the vehicle being obtained at the respective outputs of each of said identical circuits as the respective outputs of said difference value circuit.

12. An apparatus as defined in claim 11 wherein said gyrocompass means is a north-seeking gyrocompass having Anschutz damping and wherein said partial computer means includes a first multiplier having one input connected to receive a signal representing vehicle speed in the approximate north direction, said first multiplier having a second input which provides a representation of the value of the reciprocal of the radius of the earth as a fixed multiplication value signal;

a second multiplier having one input connected to receive a signal representing acceleration in the approximate north direction, said second multiplier having a second input which provides a representation of the value of the reciprocal of the gravity of the earth as its multiplication value signal;

a first computer circuit constituting a sine function generator, a second computer circuit constituting a cosine function generator, coupled from said summing circuit and responsive to signals therefrom representing geographic latitude, and first and second amplifier circuits each having an amplification factor equal to the rotational speed of the earth, the input of said first amplifier circuit being connected to the output of said first computer circuit and the input of said second amplifier circuit being connected to the output of said second computer circuit;

a first adder having a plurality of inputs, with a first of said inputs being connected to the output of said first amplifier circuit;

a first integrator having its input connected to the output of said first adder for produding an output signal representing the system error angle in the azimuth plane;

a third multiplier having one imput connected to the output of said second amplifier circuit;

a second adder having a first input connected to the output of said third miltiplier and a second input connected to the output of said first multiplier;

a second integrator having its input connected to the output of said second adder for producing an output signal representing the system error angle in the elevational plane;

a fourth multiplier having one input connected to the output of said second integrator and having its output connected to a second input of said first adder;

a fifth multiplier having one input connected to the output of said second multiplier and having its output connected to a third input of said first adder;

first setting means connected to a second input of each of said fourth and fifth multipliers for supplying thereto a constant value multiplicand signal representing the mechanical characteristics of Said gyrocompass;

a third adder having three inputs and an output, with the first of its inputs being connected to the output of said second multiplier and the second of its inputs being connected to the output of said second integrator;

a third integrator having its input connected to said third adder output;

a sixth multiplier having one input connected to the output of said third integrator and having its output connected to the third of the inputs of said third adder;

second setting means connected to a second input of said sixth multiplier for supplying thereto a gyroconstant value multiplicand signal representing the damping characteristics of said gyrocompass;

a seventh multiplier having one input connected to the output of said sixth multiplier and having its output connected to a fourth input of said first adder; and

third setting means connected to a second input of said seventh multiplier for supplying thereto a constant value multiplicand signal representing the design of the damping of said gyrocompass;

wherein the output from said sixth multiplier is a signal representing the system error angle and all of said integrators possess the same integration time which is equal to the set time interval.

13. An apparatus as defined in claim 1, wherein:

said logic circuit comprises a first computer circuit constituting a sine function generator, a second computer circuit constituting a cosine function generator, an integrator, a first multiplier and a second multiplier; and

said second input of said logic circuit is connected to the input of each of said computer circuits;

said first input of said logic circuit means is connected between the output of said calculating circuit means and the input to said integrator;

the output of said integrator is connected to a first input of each of said multipliers;

the output of each said computer circuit is connected to a second input of a respective one of said multipliers, the output from said first multiplier is connected to a first input of said summing circuit for feeding thereto a signal representative of the path component in the east/west direction; and

the output from said second multiplier is connected to a second input of said summing circuit for feeding thereto a signal representative of the path component in the north/sourth direction thereto.

14. An apparatus as defined in claim 1 wherein said summing circuit of said navigational computer means produces geographic latitude representing signals at its said output means, and said system error angle computer means includes:

summation circuit means for forming a first auxiliary parameter, said summation circuit having a plurality of inputs, one of which is connected to the output from the speed angle circuit means and a second of which is connected to the output from said gyrocompass;

a computer circuit means for forming the course error as the first system error angle, and having a first input connected to the output of said summation circuit means, a second input connected to said output means of said summing circuit in said navigational computer means for the geographic latitude representing signals, and a third input connected to the output of said calculating circuit means;

adder means for forming a second auxiliary parameter and having an input connected to the output of said summation circuit means and the output from said computer circuit means;

speed former circuit means for forming the speed representations in the approximate north direction and in the approximate east direction and having two inputs connected respectively to the output of said adder means and the output of said calculating circuit means;

a partial computer means having two inputs directly connected, respectively, to two outputs of said speed former circuit means, and having a third input connected to said output means of said summing circuit in said navigational computer means for receiving a signal therefrom representative of geographic latItude, said partial computer having an output at which appears a representation of a single system error and which is connected directly to a further input of said summation circuit means; and

an adder circuit means having a first input connected to the output from said partial computer means, a second input connected to the output of said computer circuit means and an output at which appears a signal representation of the system error angle.