Mandibular motion monitoring system

• US 4,836,778 A
• Filed: 05/26/1987
• Issued: 06/06/1989
• Est. Priority Date: 05/26/1987
• Status: Expired due to Fees

• Current Assignee: Vexcel Corporation (Microsoft Corporation)
• Original Assignee: Vexcel Corporation (Microsoft Corporation)
• Inventors: Baumrind, Sheldon, Curry, Sean
• Primary Examiner(s): Wilson, John J.
• Application Number:
  US07/053,654
• Time in Patent Office: 742 Days
• Field of Search: 433/69, 433/68, 433/5, 128/777, 356/152, 356/141
• US Class Current: 433/69
• CPC Class Codes: A61B 2090/363 Use of fiducial points
• CPC Class Codes: A61B 2090/3945 Active visible markers, e.g. light emitting diodes
• CPC Class Codes: A61C 19/045 for recording mandibular movement, e.g. face bows

Abstract

A method and apparatus for monitoring, storing and displaying movements of a person'"'"'s mandible in relation to the cranium, comprises a plurality of infrared LED'"'"'s securely mounted to the cranium and to the jaw, in immovable relation to the mandible. The location of each LED, as determined by photodiodes as the LED'"'"'s are sequentially turned on and off, is compared against an established three dimensional system frame of reference and through distinct local frames of reference associated with the cranium and the jaw, respectively, within the system frame of reference. A pointer, also provided with LED'"'"'s is used to locate specific points on the mandible in reference to the movement described by the LED'"'"'s attached to the lower jaw. The data is collected, calibrated and stored by a computer for subsequent display and analysis, either alone or in conjunction with a video display of the person'"'"'s actual head and jaw as the data was taken.

Claims

1. The method of tracing the movement of a minor body in space in relation to a major body that is also movable in space where the minor body is connected to, and supported by, the major body in such a way that movement of the major body is imparted to the minor body while the minor body is movable in relation to the major body, comprising the steps of:

positioning a first light detector and a second light detector in immovable positions and in fixed, spaced-apart relation to each other, where said first and second light detectors each has a planar light-sensitive surface that has the capability of generating electrical signals indicative of the physical location where said light is incident on said light-sensitive surface and a lens system for focusing a beam of light onto the light-sensitive surface;

defining a first planar two-dimensional coordinate system for said first detector for indicating the position of an incident light spot on the light-sensitive surface of the first detector, and defining a second planar two-dimensional coordinate system for said second detector for indicating the position of an incident light spot on the light-sensitive surface of the second detector;

defining a system frame of reference in terms of a three-dimensional coordinate system by positioning a plurality of calibraiton light-emitting sources in fixed, precisely measured spatial relation to each other in the field of vision of the first and second detectors, detecting the positions of said calibration light-emitting sources with the first and second detectors, and calibrating the image coordinate systems of said first and second detectors to correspond with the measured spatial relationships of the calibration light-emitting sources;

attaching at least three major body light-emitting sources in fixed spaced-apart relation to each other on said major body, and attaching at least three minor body light-emitting sources in fixed spaced-apart relation to each other on said minor body;

detecting the locations of said major body light-emitting sources and of said minor body light-emitting sources in the system frame of reference with said first and second detectors, and calculating three-dimensional image coordinate designations for each of those locations as a function of the respective first and second two-dimensional coordinates of the incident light spots on the respective light-sensitive surfaces of the first and second detectors;

transforming said coordinate designations of said minor body light-emitting sources to a local major frame of reference defined by the positions of said major body light-emitting sources by defining a local major coordinate system that is fixed in spatial relation to said major body light-emitting sources, defining a local minor body coordinate system that is fixed in spatial relation to said minor body light-emitting sources, and offsetting the local minor coordinates of the minor body light-emitting sources with the local major coordinate system; and

moving the minor body in relation to the major body for a period of time while detecting positions of both the major body light-emitting sources and the minor body light-emitting sources and transforming coordinates of the positions detected to the local major coordinate system.

2. The method of claim 1, including the tracking of a selected individual point on the minor body, comprising the steps of:

positioning at least three pointer light-emitting sources on a rigid pointer that has a pointer tip;

measuring precisely the spatial relations of said pointer light-emitting sources to each other and to said pointer tip;

positioning said pointer tip on a selected point on the minor body to be tracked;

detecting the locations of said pointer light-emitting sources along with detecting the locations of said major and minor body light-emitting sources;

calculating three-dimensional image coordinates for each of those locations of the detected pointer, major body, and minor body light-emitting sources as functions of the respective first and second two-dimensional coordinates of the incident light spots on the respective light-sensitive surfaces of the first and second detectors focused thereon from the light-emitting sources;

determining the coordinates of said selected point in the minor local coordinate system as a function of the spatial relations of said pointer tip to said pointer light-emitting sources and as a function said pointer light-emitting sources to said minor body light-emitting sources;

transforming the coordinates of said selected point and of said minor body light-emitting sources to said major coordinate system;

moving the minor body in relation to the major body for a period of time while detecting sequential positions of both the major body light-emitting sources and the minor body light-emitting sources;

determining the coordinates of said selected point as a function of its fixed spatial relation to the minor body light-emitting sources in sequential positions of the minor body light-emitting sources as the minor body moves; and

transforming the local minor coordinates of said selected point to the local major coordinate system.

3. The method of claim 2, including the step of displaying said selected point on a visual display device as a function of its local major coordinates as it moves.

4. The method of claim 2, including the steps of defining an anatomic frame of reference in fixed spatial relation to permanent anatomic reference points on said major body and transforming the three-dimensional coordinates of said major and minor body light-emitting sources from said local major coordinates system to three-dimensional anatomic coordinates in fixed spatial relation to said anatomic frame of reference.

5. The method of claim 4, including the steps of:

positioning said pointer tip sequentially on three selected permanent anatomic reference points on said major body, and, with the pointer tip positioned at each of said selected anatomic reference points, detecting the locations of said pointer light-emitting sources along with detecting the positions of the major body light-emitting sources;

defining an anatomic coordinate system in a fixed spacial relationship to the positions of said anatomic reference points; and

using the spatial relationships of said anatomic reference points to said major body light-emitting sources, transforming said local major coordinate system of reference to said anatomic coordinate system of reference.

6. The method of claim 5, including the steps of transforming the local major coordinates of said selected point on said minor body being tracked into three-dimensional coordinates in terms of said anatomic coordinate reference system.

7. The method of claim 6, including the steps of selecting and placing the pointer tip on additional points on the minor body in sequence, determining the coordinates of these additional points in the anatomic reference system, and tracing and recording these points in relation to the anatomical coordinates of the minor body light-emitting sources as they move with the minor body.

8. The method of claim 7, including the steps of displaying the movements of the selected points on the minor body on a visual display device as a function of the sequential anatomic reference coordinates of the selected points as they move with the minor body.

9. The method of claim 8, including the steps of video recording in digital data format the minor and major bodies simultaneously as the movements of the selected points are being detected and recorded, merging the data of the video image with the coordinate data of the selected points, and displaying the video image of the moving major and minor bodies together with an image of the moving selected points superimposed on each other and moving together at the same speeds.

10. The method of claim 9, including the steps of determining the axis of rotation of the minor body from the anatomic coordinate data of the moving selected points on the minor body, and recording the anatomic coordinates of the axis of rotation.

11. The method of claim 10, including the step of physically locating the axis of rotation on the minor body by positioning said pointer tip adjacent the minor body and moving it on said minor body while continuously detecting the pointer light-emitting sources and determining the anatomic coordinates of the pointer tip as it moves on the minor body and continuously comparing these anatomic coordinates of the moving pointer tip with the anatomic coordinates of the axis of rotation, and providing a signal perceptible to a human sense when the anatomic coordinates of the pointer tip coincide with the antomic coordinates of the point of rotation.

12. The method of claim 2, including the step of positioning four pointer light-emitting sources on said pointer.

13. The method of claim 12, including the step of positioning one of said pointer light-emitting sources immediately adjacent said pointer tip and positioning the other three pointer light-emitting sources more remote from said pointer tip.

14. The method of claim 1, including the steps of:

sensing photovoltages at four points on diametrically opposite peripheral sides of said light-sensitive surface of each of said first and second detectors;

amplifying each sensed voltage immediately adjacent said light-sensitive surface; and

converting said four amplified voltage signals from analog to digital form, and determining orthogonal X and Y planar two-dimensional coordinates of the position of the focused light spot on the light sensitive surface as a function of respective photovoltage magnitudes at each lead, distances between leads, and distances from the position of the focused incident light spot to the respective leads.

15. The method of claim 14, including the steps of switching on only one light-emitting source one at a time in a predetermined sequence and in a predetermined time cycle, and detecting the light emitted by each light-emitting source one at a time with said first and second detectors, determining the three-dimensional image coordinates of each light-emitting source simultaneously with detecting the emitted light as the light-emitting source is turned on, and storing said coordinates along with the time of detection.

16. The method of claim 15, including the step of averaging the coordinates for four sequential detections of each light-emitting source and storing the averaged coordinates.

17. The method of claim 14, including the steps of delaying determination of the X and Y planar coordinates for a sufficient time for the photovoltage induced by the incident light to stabilize.

18. The method of claim 17, including the steps of continuously detecting the photovoltage induced by each incident light spot on the light-sensitive surface and determining the rate of change of the voltage, and, when the rate of change of the voltage decreases to a predetermined threshold rate of change, initiating the step of determining the X-Y planar coordinates.

19. The method of claim 1, including the steps of attaching four major light-emitting sources on said major body, and attaching four minor light-emitting sources on said minor body.

20. The method of claim 19, including the steps of attaching said four major light-emitting sources in at least two different planes that are spaced different distances from the detectors, and attaching said four minor light-emitting sources in at least two different planes that are spaced different distances from the detectors.

21. Mandibular movement monitoring apparatus for detecting, monitoring, and analyzing movement of a person'"'"'s mandible in relation to the person'"'"'s cranium as the cranium and the mandible move in space, said apparatus comprising:

two photo detector means for detecting light spots incident on photo-sensitive surfaces in a manner indicative of the specific position of the incident light spot on the photo detector surfaces, said photodetector means including lens means for focusing incident light onto said photo-sensitive surfaces, and signal output means for outputting data signals;

processing means for processing said incident spot data signals from said detector means to determine three-dimensional spatial coordinates of the sources of the incident light spots;

four upper light source means for producing light to be detected by said detector means;

four lower light source means for producing light to be detected by said detector means;

harness means for mounting said upper light source means in immovable relation to the person'"'"'s cranium and for mounting the lower light source means in immovable relation to the person'"'"'s mandible, said four upper light source means being mounted in at least two different planes that are different distances from said detector means, and said four lower light source means being mounted in at least two different planes that are different distances from said detector means;

pointer means for establishing spacial relationships of selected points on the person'"'"'s mandible and cranium in relation to said upper and lower light source means, said pointer means including a rigid body with a designated pointer tip thereon, first pointer light-emitting means positioned immediately adjacent said pointer tip for emitting light from a location close to said tip, and second, third, and fourth pointer light-emitting means positioned more remotely from said pointer tip and in precisely measured spaced-apart relation to each other, to said first pointer light-emitting means, and to said pointer tip; and

displaying means for displaying selected points in terms of three-dimensional coordinate reference systems.

22. The apparatus of claim 21, including a calibration cube having a plurality of calibration light-emitting means mounted thereon in precisely measured spatial relations to each other for calibrating said detector means and said data processing means to a predetermined spatial reference system defined by the positions of said calibration light-emitting means on said calibration cube.

23. Harness apparatus for mounting LED'"'"'s on a person'"'"'s head, some of which LED'"'"'s are mounted in immovable relation to the person'"'"'s cranium and some of which LED'"'"'s are mounted in immovable relation to the person'"'"'s mandible, comprising:

an upper frame comprised of an elongated upper cross bar, a nose piece attached to the upper cross bar for supporting the upper frame on the person'"'"'s nose, two elongated ear bow members, one of which extends rearwardly from one end of the upper cross bar and the other of which extends rearwardly from the other end of the upper cross bar;

a lower frame comprised of an elongated lower cross bar, and a chin cup attached to the lower cross bar for positioning under the person'"'"'s chin;

two spaced-apart left side elastic bands, one of which extends between the proximal end of the left ear bow and the lower cross bar and the other of which extends from the distal end of the left ear bow to the left rear corner of the chin cup;

two spaced-apart right side elastic bands, one of which extends between the proximal end of the right ear bow and the lower cross bar and the other of which extends from the distal end of the right ear bow to the right rear corner of the chin cup;

a first upper LED bracket extending upwardly and forwardly from the left end of the upper cross bar, a second upper LED bracket extending upwardly and forwardly from the right end of the upper cross bar, a third upper LED bracket extending laterally outward from the left ear bow, a fourth LED bracket extending laterally outward from the right ear bow, and an LED mounted on the distal end of each of said first, second, third, and fourth upper LED brackets; and

a first lower LED bracket extending forwardly from the left end of said lower cross bar, as second lower LED bracket extending forwardly from the right end of said lower cross bar, a third lower LED bracket extending upwardly from the left end of said lower cross bar, a fourth lower LED bracket extending upwardly from the right end of said lower cross bar, and an LED mounted on the distal end of each of said first, second, third, and fourth lower LED brackets.