System for measuring position and/or velocity

• US 4,195,425 A
• Filed: 01/04/1978
• Issued: 04/01/1980
• Est. Priority Date: 07/17/1972
• Status: Expired due to Term

• Current Assignee: Ernst Leitz Wetzlar GmbH (ACM Project Development Co.)
• Original Assignee: Ernst Leitz Wetzlar GmbH (ACM Project Development Co.)
• Inventors: Heitmann, Knut, Leitz, Ludwig
• Primary Examiner(s): Buczinski, S. C.
• Application Number:
  US05/866,908
• Time in Patent Office: 818 Days
• Field of Search: 356/1, 356/4, 356/5, 356/28, 356/156, 356/172, 352/140, 340/53, 180/98
• US Class Current: 356/28
• CPC Class Codes: G01P 3/36 Devices characterised by the use of optical means, e.g. using infrared, visible, or ultraviolet light G01P3/68 takes precedence; gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams G01C19/64
• CPC Class Codes: G01S 11/12 using electromagnetic waves other than radio waves

Abstract

System for measuring the relative position and/or velocity of two objects with respect to each other and/or with respect to a common reference system, such as the ground, according to the magnitude and direction thereof, using electro-optical measuring means, the improvement comprising:

(1) producing images of the object to be measured in at least two different spatial positions;

(2) producing A.C. electrical signals of different frequency proportional to the relative movements of these images to at least one optical correlation system; and

(3) evaluating these signals, with the use of the trigonometrical relationships of the perspective imaging, in a computer to determine the measured values.

Claims

1. In a system for measuring the relative position and/or movement in magnitude and direction of an object being without special optical markers thereon, said object being measured with respect to a reference by using at least an imaging system, at least one grating positioned at least in the vicinity of the image plane of said imaging system and coordinated with at least one measuring direction and photoelectric detectors associated with said grating and generating electrical signals according to light fluxes emanating from said grating, the improvement comprising:

forming by said imaging system in a first and/or at least in a second measuring direction an image each of said object and said reference respectively on said grating in positions spatially separated, said images of said object and said reference differing from one another in image scale and perspective caused by different object distance and different reference distance respectively from said grating;

generating for each measuring direction according to the interaction between said images and said grating electrical A.C. signals, the frequencies of which differ in dependence upon said different image scale and said perspective and being proportional to the relative position and/or movement of said object to be measured; and

evaluating said electrical A.C. signals by employing the trigonometrical relationships of said image scale and said perspective for producing signals indicating the position and the movement of said object, said trigonometrical relationships of said image scale being defined by the ratio image size/object size, said trigonometrical relationships of said perspective being defined by the depiction of spatially extended objects on a plane surface.

2. The system of claim 1, comprising an optical correlator having said at least one imaging system, at least said one grating positioned at least in the vicinity of the image plane of said imaging system and coordinated with at least one measuring direction, and said photoelectric detectors, said imaging system forming in a first and/or at least in a second measuring direction from said object and said reference images differing in image scale and perspective on said grating in positions located in at least one plane but spatially separated, said photoelectric detectors generating said electrical A.C. signals from light fluxes leaving said grating;

processing said A.C. signals of said photoelectric detectors in computing means by employing said trigonometrical relationships, whereby resulting signals are also proportional to the relative movement and the position between said images and said grating, said resulting signals being further proportional to the relative movement and the position between said measuring system and said objects and said resulting signals being yet further proportional to the relative movement and the position between said object and said reference object.

3. The system of claim 1, comprising a first optical correlator having said at least one imaging system, said at least one grating positioned at least in the vicinity of a first image plane of said first imaging system, and coordinated with at least one measuring direction, and first photoelectric detectors associated with said first grating and generating first electrical A.C. signals according to light fluxes emanating from said first grating, using as said reference a second optical correlator containing at least a second imaging system, at least a second grating positioned at least in the vicinity of an image plane of said second imaging system and also coordinated with at least one measuring direction, and second photoelectric detectors associated with said second grating and generating second electrical A.C. signals according to light fluxes emanating from said second grating, arranging said first and said second correlators in positions spatially separated with respect to said object to be measured, forming from said object to be measured one image each in said first and second image plane of said optical correlators;

said images differing from one another in image scale and perspective thus causing a difference in frequency between said first and second electrical A.C. signals;

processing said first and second A.C. electrical signals in computing means by employing said trigonometrical relationships of said image scale and said perspective, the resulting signals therefrom being proportional to the relative movement and the position of said object.

4. The system of claim 1, wherein said positions spatially separated are disposed side-by-side with respect to said object to be measured.

5. The system of claim 1, wherein said positions spatially separated have angles of inclination differing with respect to said object to be measured.

6. The system of claim 1, wherein said images in said positions spatially separated are interrogated for generating said electrical A.C. signals.

7. The system of claim 2, wherein the distance between said positions spatially separated is a value given by the arrangement and the optical properties of said optical correlator and means are provided for calculating the magnitude and direction of the relative movement from said A.C. signals of said photoelectric detectors.

8. The system of claim 1, wherein the direction of relative movement between said object and reference is given and means are provided for calculating the distance and magnitude of the movement of said object from said A.C. signals of said photoelectric detectors.

9. The system of claim 1, wherein the magnitude of said movement is given and means are provided for calculating the distance and the angle of direction between said object to be measured and said reference from said A.C. signals.

10. In a system for measuring the relative position and/or movement in magnitude and direction of an object being without special optical markers thereon, said object being measured with respect to a reference using at least one imaging system, at least one grating positioned at least in the vicinity of the image plane of said imaging system and coordinated with at least one measuring direction, and photoelectric detectors associated with said grating and generating electrical A.C. signals according to light fluxes emanating from said grating, the improvement comprising:

using said system on an airplane having means for determining values of flying height and flying velocity;

providing said system with a plurality of optical correlators having imaging means and grating means as well as photoelectric detectors for detecting said object defined by the ground under a plurality of viewing angles;

producing from said object to be measured by said imaging means of said optical correlators images differing from one another in image scale and perspective in at least two distinct planes defining at least two positions spatially separated;

generating from light fluxes leaving said grating means A.C. signals the frequencies of which differ in dependence upon said image scale and said perspective;

said signals being also proportional to the relative position and/or movement between said images and said gratings; and

determining from the maxima and minima of said signal frequencies said viewing angles and by including said values of flying height and flight velocity the approach angle of said plane.

11. In an apparatus for measuring the relative position and/or movement in magnitude and direction of an object without special optical markers thereon, said object being measured with respect to a reference, by using at least one optical correlator having at least one imaging system, at least one grating positioned at least in the vicinity of the image plane of said imaging system and coordinated with a first and/or at least in a second measuring direction, the photoelectric detectors and imaging with said imaging system said object to be measured and said reference on said grating and converting the light fluxes leaving said grating by said photoelectric detectors, the output signals of which are processed in computing means, the improvement comprising:

said apparatus mounted in a first vehicle;

said apparatus being provided with said at least one optical correlator equipped with means for indicating the correct arithmetical sign of said movement and having a broad directional characteristic;

said optical correlator disposed for detecting lateral sections of said roadway as said reference and a second vehicle passing by as said object to be measured, said lateral sections of said roadway and said second vehicle being imaged by said imaging system of said optical correlator on said grating in positions spatially separated, said images of said lateral sections of said roadway and said second vehicle respectively differing from one another in image scale and perspective caused by the different distances of said sections of said roadway and said second vehicle respectively from said grating, said photoelectric detectors of said optical correlator generating electrical A.C. signals, the frequencies of which differ in dependence upon said different image scale and perspective and being processed in said computing means for determining in magnitude and sign the relative movement and/or the distance of said second vehicle and/or the movement of said first vehicle with respect to said lateral sections of said roadway.

12. The apparatus of claim 11, wherein said optical correlator is mounted for detecting sections of said roadway perpendicularly moving to the direction of motion of said first vehicle.

13. In an apparatus for measuring the relative position and/or movement in magnitude and direction of an object without special optical markers thereon, said object being measured with respect to a reference, an optical correlator imaging with an imaging system said object to be measured on a grating coordinated with at least one measuring direction, and converting the light fluxes leaving said grating by photoelectric detectors the output signals of which are processed in computing means, the improvement comprising:

said apparatus mounted in a slide projector having an optical axis to detect as said object to be measured a diapositive positioned along said optical axis and in a plane perpendicularly extending to said optical axis for a position of optimum focusing;

said apparatus provided with two of said optical correlators laterally arranged to said optical axis;

said optical correlators furnished with a common imaging system and a common grating, each defining a plane intersecting with said plane of said diapositive in a unique line according to the Scheimpflug condition;

said optical correlators further furnished with a photoelectric detector each, the spatial positions of which define separate beams emanating from said object and intersecting with the optical axis of said imaging system in nodal points;

said imaging system forming in dependence upon said arrangement of said grating, images of different image scale and perspective;

said photoelectric detectors generating from each of said images electrical A.C. signals differing from one another in frequency and being out of phase upon displacement of said object and being in phase upon the position of optimum focusing;

said position of optimum focusing being attained when said nodal points are equidistant of said optical axis of said imaging system;

said computing means being connected to a control circuit for the adjustment of said diapositive into a position of optimum focusing; and

an electric drive provided for continuous movement of said gratings of said optical correlators.

14. In an apparatus for measuring the relative position and/or movement in magnitude and direction of an object without special optical markers thereon with respect to a reference object bearing no special optical markers thereon, an optical correlator imaging with an imaging system said object to be measured and said reference object with different image scale and perspective on a grating coordinated with at least one measuring direction and converting the light fluxes leaving said grating by photoelectric detectors, the output signals of which are processed in computing means, the improvement comprising:

said apparatus mounted on a vehicle;

said apparatus being provided with an optical correlator having at least said one grating subdivided in sections of different rulings;

said sections of said grating being arranged side-by-side in a plane for detecting under different viewing angles the movement of the surroundings of said vehicle inclusive the roadway in vertical and horizontal direction and generating therefrom electrical A.C. signals by said photoelectric detectors of said optical correlator;

means for laterally oscillating said grating in the plane;

said grating associated with a mask off device which exposes only those of said grating sections in which roadway obstacles on said roadway on collision course are reproduced even as said vehicle traverses a curve; and

computing means having terminals connected to said photoelectric detectors.

15. The apparatus of claim 14, wherein sections of said grating are used as reflection gratings for light incident from both sides;

thus defining at least two optical correlators located one behind the other with respect to said object to be measured.

16. In an apparatus for measuring the relative position and/or movement in magnitude and direction of an object without special optical markers thereon, said object being measured by using at least one optical correlator having at least one imaging system, at least one grating positioned at least in the vicinity of the image plane of said imaging system and coordinated with a first and/or at least in a second measuring direction and photoelectric detectors and imaging with said imaging system said object to be measured on said grating and converting the light fluxes leaving said grating by said photoelectric detectors, the output signals of which are processed in computing means, the improvement comprising:

said imaging system of said optical correlator defining at least two nodal points differently spaced with respect to said object to be measured and said reference respectively, light rays coordinated with said at least two nodal points having axes intersecting each other in the direction of said object and said reference respectively, said light rays producing at least in two separate spatial positions of said image plane two images of said object to be measured and said reference respectively differing from one another in image scale and perspective caused by said different distances of said nodal points from said object to be measured and said reference respectively, said photoelectric detectors connected to the terminals of said computing means generating electrical signals from light leaving said grating, the frequencies of said electrical signals differing in dependence upon said different image scale and said perspective of said images.

17. The apparatus of claim 16, wherein at least two optical correlators are provided in positions spatially separated, each containing one optical imaging system defining nodal points which are differently spaced with respect to said object to be measured and wherein the axes of light rays coordinated to said nodal points of said imaging systems intersect each other in the direction of said object to be measured.