Smart tracking system

• US 5,384,594 A
• Filed: 07/09/1993
• Issued: 01/24/1995
• Est. Priority Date: 09/05/1990
• Status: Expired due to Fees

• Current Assignee: Jonathan D. Sieber, Joseph S. Sieber, William K. Stewart
• Original Assignee: Jonathan D. Sieber, Joseph S. Sieber, William K. Stewart
• Inventors: Stewart, William K., Sieber, Joseph S., Sieber, Jonathan D.
• Primary Examiner(s): Lobo, Ian J.
• Application Number:
  US08/089,760
• Time in Patent Office: 564 Days
• Field of Search: 358/125, 358/126, 358/455, 358/516, 364/516, 348/169
• US Class Current: 348/169
• CPC Class Codes: G01S 3/807 the desired condition being maintained automatically

Abstract

A smart tracking system includes a digital processor for selectively processing error signals representing the angular error between a tracked subject and the orientation of the tracking device/camera. In one embodiment, the user selects a set of data values representating the operating parameters of the system in a specific operational mode. The processor uses the selected variables to perform a series of computations which selectively modify the angular error signals in a manner that will produce a video picture which is visually and aesthetically pleasing to human viewers. In a second embodiment, the set of data values characterizing the operational mode of the system automatically are selected by the processor based on the past history of the subject'"'"'s motion and the current operation mode of the system.

Claims

1. A system permitting a device to point at and track the movements of a moving subject, comprising:

a. a signal source generating signals which can be tracked;

b. a control device receiving signals from the source and generating relative orientation data therefrom in the form of control signals, said orientation data varying as continuous functions with changes in the relative angular position of the subject;

c. memory storing plural sets of data values, each of said data value sets representing selected values for processing said control signals in anticipation of future relative motion of the subject based on past motion of the subject;

d. a selector selecting one of said sets of data values;

e. a processor processing said control signals in accordance with the one of said sets of data values selected by said selector to produce processed control signals; and

f. a drive unit moving the device about at least one axis in response to said processed control signals to maintain the device pointed at the subject.

2. The system of claim 1 wherein each of said data value sets comprises data values representing selected acceleration rates of the device and selected deceleration rates of the device, for a particular range of anticipated motion by the subject.

3. The system of claim 1 where each of said data value sets comprises data values representing a selected angular velocity of the device, and a maximum allowable angular error between the axis of the device and the subject, for a particular range of anticipated motion by the subject.

4. The system of any of claims 1, 2 or 3 wherein said selector comprises a user-defined signal for indicating which of said plural sets of data values is to be selected.

5. The system of any of claims 1, 2, or 3 wherein said selector comprises circuitry automatically selecting one of said plural sets of data values in anticipation of future relative motion of the subject based on past motion of the subject.

6. An apparatus intelligently and automatically tracking a moving subject with a camera comprising:

a. circuitry determining an error direction representing the present orientation of the subject relative to the camera;

b. a sensor for sensing a last direction in which the camera moved about an axis;

c. a calculator calculating an elapsed time value representing the elapsed time interval since the camera last moved;

d. a comparator comparing the last direction with the error direction, and for-comparing the elapsed time value with a predetermined value if the error direction and the last direction are not equal; and

e. a drive unit, responsive to said circuitry determining an error and said comparator moving the camera in the error direction about said one axis if the elapsed time value at least equals the predetermined value or the last direction equals the error direction.

7. The apparatus of claim 6 wherein said circuitry determining an error direction comprises:

a controller receiving source signals from the subject and continuously generating therefrom control signals representing the angular error between the position of the subject and the camera along at least one plane.

8. An apparatus permitting a camera to maintain a moving subject within the frame of a camera in a manner which is visually pleasing to a viewer, the apparatus comprising:

a. a memory storing a plurality of predetermined limits for the angular velocity and angular acceleration of the camera about an axis;

b. a drive unit, responsive to the memory moving the camera about the axis at rates not in excess of the predetermined limits to maintain the subject within the zone;

c. a mechanism defining a central zone within the camera frame and substantially symmetrical about the center of the subject;

d. a first calculator calculating a first percentage representing the total time the subject was outside the central zone during a given time interval;

e. a second calculator calculating the maximum angular velocity and maximum angular acceleration of the subject within the given time interval; and

f. circuitry, responsive to said first and said second calculators, selecting new predetermined limits from the memory storing the angular acceleration and angular velocity of the camera in anticipation of future motion of the subject.

9. The apparatus of claim 8 wherein the circuitry selecting new predetermined limits comprises a first comparator comparing the first percentage with a predetermined maximum allowable percentage stored in said memory and selecting new predetermined limits for the angular velocity and the angular acceleration of the camera when the first percentage exceeds the predetermined maximum allowable percentage.

10. The apparatus of claim 9 wherein said circuitry selecting new predetermined limits comprises a second comparator comparing the maximum angular velocity and maximum angular acceleration of the subject with the current predetermined limits for angular velocity and angular acceleration of the camera, and for selecting new predetermined limits for the angular acceleration and angular velocity of the camera when the maximum angular velocity and maximum angular acceleration of the subject are substantially less than or substantially greater than the current predetermined limits.

11. An apparatus for intelligently and automatically tracking a moving subject within the frame of a camera comprising:

a. a mechanism defining a central zone within the camera frame by a pair of angular coordinates along one axis and substantially symmetric about the center of the subject at a first time;

b. circuitry determining an angular error along said one axis between the subject and the camera at a second time;

c. circuitry determining whether the angular error is within the central zone;

d. circuitry determining an error direction representing the direction in which the camera must move to reduce the angular error at the second time, if the angular error is not within the central zone;

e. a drive unit moving the camera about said one axis in the error direction; and

f. circuitry redefining the angular coordinates of the central zone so that the central zone is shifted in a direction which is opposite the error direction.

12. The apparatus of claim 11 wherein said redefining circuitry comprises:

a first subtractor subtracting the value of one of the angular coordinates defining the central zone from the value of the angular error to form a difference value; and

a second subtractor subtracting the difference value from each of the angular coordinates to form new angular coordinates.

13. An apparatus for intelligently and automatically tracking a moving subject within the frame of a camera comprising:

a. a receiver receiving signals from the subject and generating relative orientation data therefrom in the form of control signals, said orientation data being a continuous function of the relative angular position of the subject;

b. a mechanism defining a central zone within the camera frame with a pair of angular coordinates along one axis;

c. circuitry determining, from the control signals, whether the subject is within the central zone;

d. a processor processing the control signals if the subject is not within the central zone;

e. circuitry redefining the angular coordinates describing the central zone to reorient the central zone within the camera frame; and

f. a drive unit, responsive to the processor, moving the camera about an axis to maintain the subject within the central zone.

14. An apparatus for permitting a camera to maintain a moving subject within the camera frame in a manner that is visually pleasing to a viewer, the system comprising:

a. a subject generating signals which can be tracked;

b. a controller receiving signals from the subject and continuously generating relative orientation data therefrom in the form of control signals, said control signals representing the angular error between the position of the subject and the camera along at least one plane;

c. a mechanism anticipating future relative motion of the subject based on past motion of the subject;

d. a processor responsive to said control signals, for determining whether the angular error represented by the control signals is within an acceptable range given anticipated motion by the subject, and processing said control signals if said angular error is not within the acceptable range; and

e. a drive unit, responsive to said processed control signals, selectively moving the camera about an axis to maintain the subject within the camera frame.

15. An apparatus for tracking the motion of a subject comprising:

a. a memory storing a plurality of predetermined limits for each of the angular acceleration and angular velocity of the apparatus about an axis;

b. a controller storing periodic values for each of the angular speed and angular acceleration of the subject during a given time interval and determining the motion characteristics of the subject during the given time interval from said periodic values;

c. a selector, responsive to the controller, selecting one of said plurality of predetermined limits for each of the angular acceleration and angular velocity of the apparatus in accordance with the motion characteristics of the subject; and

d. a drive unit, responsive to the selector and the memory, moving the apparatus about the axis at rates not in excess of the selected predetermined limits.

16. The apparatus of claim 15 wherein the selector further comprises a user-defined signal for indicating which of the predetermined limits in the memory are to be selected.

17. The apparatus of claim 15 wherein the selector comprises circuitry automatically selecting said predetermined limits in anticipation of future relative motion of the subject based on the motion characteristics of the subject.

18. The apparatus of claim 15 wherein the motion characteristics of the subject comprise the average angular speed and maximum angular speed of the subject during the given time interval.

19. The apparatus of claim 18 wherein the motion characteristics of the subject further comprise the average angular acceleration and maximum angular acceleration of the subject during the given time interval.

20. The apparatus of claim 19 wherein said selector comprises a first comparator comparing the maximum angular speed and maximum angular acceleration of the subject with the current predetermined limits for angular velocity and angular acceleration of the apparatus, and selecting new predetermined limits for the angular acceleration and angular velocity of the apparatus when the maximum angular speed and maximum angular acceleration of the subject are substantially less than the current predetermined limits.

21. The apparatus of claim 19 wherein said selector comprises a second comparator comparing the maximum angular speed and maximum angular acceleration of the subject with the current predetermined limits for angular velocity and angular acceleration of the apparatus, and selecting new predetermined limits for the angular acceleration and angular velocity of the apparatus when the maximum angular speed and maximum angular acceleration of the subject are substantially greater than the current predetermined limits.

22. The apparatus of claim 15 wherein the motion characteristics of the subject comprise the average displacement and maximum displacement of the subject during the given time interval.

23. The apparatus of claim 15 wherein the motion characteristics of the subject comprise a first time value representing the average elapsed time between direction reversals by the subject during the given time interval.

24. The apparatus of claim 23 wherein the memory further stores a plurality of predetermined limits for a second time value representing the minimum allowable elapsed time between direction reversals by the apparatus about the axis;

and

said drive unit further comprises circuitry reversing the direction of the apparatus about the axis once the second time value is at least equaled.

25. The apparatus of claim 24 wherein the means for selecting comprises a third comparator comparing the first time value with the current predetermined limit for the second time value, and selecting a new predetermined limit for the second time value when the first time value is greater than the current predetermined limit for the second time value.