Method for determination of head position relative to rectangular axes for observer equipped with head-mounted module

• US 20140009367A1
• Filed: 07/05/2012
• Published: 01/09/2014
• Est. Priority Date: 07/05/2012
• Status: Active Grant

• Current Assignee: Efros, Alexander, Iokhvidson, Simon, Lvovskiy, Matvey, Sofya Volfson
• Original Assignee: Efros, Alexander, Iokhvidson, Simon, Lvovskiy, Matvey, Sofya Volfson
• Inventors: Lvovskiy, Matvey, Efros, Alexander, Iokhvidson, Simon, Volfson, Sofya
• Granted Patent: US 8,786,846 B2
• Time in Patent Office: Days
• US Class Current: 345/8
• CPC Class Codes: F41G 3/225 Helmet sighting systems
• CPC Class Codes: G01S 17/875 for determining attitude
• CPC Class Codes: G01S 5/163 Determination of attitude using inertial means G01C9/00; control of attitude G05D1/49
• CPC Class Codes: G02B 27/017 Head mounted

Abstract

Method is proposed of angular coordinates determination for observer'"'"'s head relative to three mutually perpendicular axes of fixed (or tied to an object) coordinate system OXYZ (angle of roll, azimuth, elevation angle) by use of measuring system based on light-sensitive sensor with collimating lens fixed relative to coordinate system and LED lasers installed on head-mounted module HMM. Measuring device registers angular coordinates of narrow pencils of rays formed by LED lasers and provides determination of observer'"'"'s head angular coordinates in real-time. Three angles of HMM can be determined by proposed method while no less than two LED lasers are in lens field of view with angle Δ of set value and direction included between their axes. To provide specified measurement range of observer'"'"'s head angles exceeding lens field of view LED lasers matrix is installed on HMM containing LED lasers allocated in several horizontal and vertical lines

Claims

1. Method for determination of angular coordinates of the head for observer equipped with a head-mounted module (HMM) relative to fixed rectangular axes OXYZ whereas:

in order to determine vertical and horizontal angular coordinates of the observer'"'"'s head in real-time mode relative to fixed horizontal (OZ) and vertical (OY) axes first LED that is installed on the helmet-mounted module and emits a narrow pencil of rays and device for measuring of angular coordinates installed stationary relative to fixed rectangular axes OXYZ, e.g., TV camera (TVC) provided with the lens (LENS) generating dot pattern of LED light rays in the plane of light-sensitive sensor and optic axis of the lens is parallel to the axis OX and the plane of light-sensitive sensor is parallel to the vertical plane YOZ and values of angular coordinates are unambiguously connected with values of linear coordinates of corresponding dot pattern of light rays of the first LED in the plane of light-sensitive sensor;

in order to determine value of angular coordinate of observer'"'"'s head by roll in real-time—

an angle of rotation relative to the third axis (OX)—

second LED laser is installed on the helmet-mounted module in addition to the first LED laser that is turned through specified angle relative to the first, for example, horizontally (parallel to the plane XOZ) then value of angular coordinate relative to the axis OX is defined by arc sinus of the difference of vertical angular coordinates of the first and second LEDs divided by value of the angle Δ and

values of angular coordinates of the first and second LEDs are unambiguously connected with values of linear coordinates of corresponding dot patterns of light rays of mentioned LEDs in the plane of light-sensitive sensor.

2. Method by claim 1 whereas in order to represent images generated by the narrow pencils of light emitted by the LED in the form of luminous dots in the plane of light-sensitive sensor collimating lens focused in infinity is used in TV camera (TVC).

3. Method by claim 1 whereas in order to determine three angular coordinates of observer'"'"'s head (horizontal, vertical and roll) the sizes of angular field of view of TVC, e.g., that has squared shape, should be such that axes of no less than two LED lasers installed on the head-mounted module HMM, could be in the field of view constantly.

4. Method by claim 1 whereas in order to provide the required ranges of measuring of horizontal and vertical angular coordinates of the observer'"'"'s head that exceed the TVC angular field of view the LED lasers matrix is installed on the head-mounted module HMM with the LED lasers allocated so that they form several horizontal and vertical lines with specified spacing between the LED lasers and each of the LED laser is turned by specified angles relative to the next LED lasers.

5. Method by claim 4 whereas any angle between the axes of the next LED lasers in every horizontal line of LEDs should be less than horizontal size of TVC angular field of view and total angular size of horizontal line is equal or exceeding the size of specified range of measurement of angles of observer'"'"'s head rotation horizontally.

6. Method by claim 4 whereas in each vertical line of LEDs any angle between the axes of two next LED lasers should be less than vertical angular size of TVC field of view and total angular size of vertical line is equal or exceeding the size of specified range of measurement of angles of observer'"'"'s head rotation vertically.

7. Method by claim 1 whereas in order to identify each of two LED lasers operating in TVC field of view the LED lasers are switched on by turns and, namely, during each even frame of TV scan the first LED laser is emitting and during each uneven frame—

the second LED laser.

8. Method by claim 4 whereas in order to provide the continuous process when measuring the angular coordinates of observer'"'"'s head within full specified range of angles in case the axis of at least one LED laser from the acting couple of LED lasers is coming up to any border of TVC field of view horizontally (vertically) then present LED laser is switched off and simultaneously the next horizontal (vertical) LED laser located in TVC field of view is switched on.

9. Method by claim 2 whereas in order to increase the virtual size of the LENS entrance pupil in horizontal direction a plane-parallel plate PL is installed in front of the LENS made of optical glass or acrylic that consists of the set of flat light-dividing components glued together between each other creating the totality of mutually parallel slanted beam splitters that are vertically oriented.

10. Method by claim 9 whereas in order to increase virtual size of LENS entrance pupil in vertical direction the second PL is installed in front of the first PL that consists of the set of flat beam splitters components glued together between each other made of optical glass or acrylic creating the totality of mutually parallel slanted beam splitters that are horizontally oriented.

11. Method by claim 10 whereas in the first and second plates PL the beam splitters should be sloped towards the input and output facets of the plate at an angle δ

_h providing capability for conditions of total reflection of rays to be met for the even reflections from input and output facets.

12. Method by claim 11 whereas in order to improve the efficiency of LENS operation with the first and second PL the LENS entrance pupil should be square and the size of side of mentioned square have to be equal to doubled product of value of plate PL thickness and cotangent of angle of inclination of beam splitters towards the input and output facets of the plates.

13. Method by claim 1 whereas a TV-camera (TVC) is carried out with the light-sensitive sensor on the basis of CCD (Charge Coupled Device) or CMOS (Complementary-symmetry/metal-oxide semiconductor)—

matrix is used in the measuring device for angular coordinates determination and a frame rate of TV-scan for TVC is selected so that required accuracy and reliability of measurement can be attainable.

14. Method by claim 1 whereas in order to eliminate the light noise obstructing the observer'"'"'s view the LED lasers are applied emitting light within invisible spectral range, e.g., IR-range (0.8-1.0 mc).