Method and system for tracking attitude

Abstract

A method and system for tracking attitude of a device includes fixing a two-dimensional array of photosensors to the device and using the array to form a reference frame and a sample frame of images. The fields of view of the sample and reference frames largely overlap, so that there are common imaged features from frame to frame. Sample frames are correlated with the reference frame to detect differences in location of the common features. Based upon detection of correlations of features, an attitudinal signal indicative of pitch, yaw, and/or roll is generated. In the preferred embodiment, the attitudinal signal is used to manipulate a screen cursor of a display system, such as a remote interactive video system (RIVS). However, attitudinal tracking using the invention may be employed in other applications. Another aspect of the invention is that the two-dimensional array is configured to compensate for any curvilinear distortions introduced by a lens system for imaging the features within the field of view of the array.A movable device, such as an optical mouse, includes a housing, a lens system in the housing and an array of photosensors in the housing for acquiring images in light applied to the array by the lens system, the array disposed in a plurality of rows and columns defining an optical axis, adjacent columns being spaced apart by boundaries having curvatures increasing with departure from the optical axis sufficient to compensate for curvilinear distortion introduced in the images by characteristics of the lens system, the array comparing data from the images to indicate motion of features of the images relative to the housing.

1. An arrangement of a sensor and optics comprising:
 an array of photosensors; and  
 a lens system for providing a focus for imaging by said array, said lens system having a characteristic of Introducing curvilinear distortion of an image to said array;  
 said array having a shape to achieve compensation of said curvilinear distortion, including having arcuate edges to establish said compensation;  
 wherein said photosensors are disposed in a plurality of columns and a plurality of rows and wherein said photosensors combine to define an optical axis for said array, adjacent columns being spaced apart by an arcuate boundary, with curvatures of said arcuate boundaries increasing with departure from said optical axis.  
 
     
     
       2. The arrangement of  claim 1  wherein adjacent rows are paced apart by second arcuate boundaries, with curvature of said second arcuate boundaries increasing with departure from said optical axis. 
     
     
       3. An arrangement of a sensor and optics comprising:
 a two-dimensional array of photosensors; and  
 a lens system for providing a focus for imaging by said array, said lens system having a characteristic of optically introducing curvilinear distortion of an Image to said array;  
 said array having a curvilinear shape to achieve compensation of said curvilinear distortion, including having a plurality of arcuate outer edges to establish said compensation, said photosensors being varied dimensionally to define said curvilinear shape, said curvilinear shape being aligned relative to said curvilinear distortion to introduce a physical distortion that offsets said optically introduced curvilinear distortion;  
 wherein said photosensors are disposed in a plurality of columns and a plurality of rows and wherein said photosensors combine to define an optical axis for said array, adjacent columns being spaced apart by an arcuate boundary, with curvatures of said arcuate boundaries increasing with departure from said optical axis.  
 
     
     
       4. The arrangement of  claim 3  wherein adjacent rows are spaced apart by second arcuate boundaries, with curvature of said second arcuate boundaries increasing with departure from said optical axis. 
     
     
       5. A movable device, comprising:
   a housing;        a lens system in the housing; and        an array of photosensors in the housing for acquiring images in light applied to the array by the lens system, the array disposed in a plurality of rows and columns defining an optical axis, adjacent columns being spaced apart by boundaries having curvatures increasing with departure from the optical axis sufficient to compensate for curvilinear distortion introduced in the images by characteristics of the lens system, the array comparing data from the images to indicate motion of features of the images relative to the housing.     
     
     
       6. The invention of  claim 5 , wherein the array compares data from a first image with data from a subsequently acquired image to indicate the relative motion. 
     
     
       7. The invention of  claim 5 , wherein the array compares data from a first image with data from a subsequently acquired image during an interval between acquiring the images. 
     
     
       8. The invention of  claim 5 , wherein the array compares data from a first image with data from a series of subsequently acquired images to indicate the relative motion. 
     
     
       9. The invention of  claim 8 , wherein the array compares data from the first image with data from the series of subsequently acquired images and then compares data from the second image with data from the series of subsequently acquired images. 
     
     
       10. The invention of  claim 9 , wherein the array replaces data from the first image with data from the second image for comparison with data from the series of subsequently acquired images each time a threshold is reached. 
     
     
       11. The invention of  claim 10 , wherein the threshold comprises:
   a time threshold.     
     
     
       12. The invention of  claim 10 , wherein the threshold comprises:
   a threshold based on the relative movement.     
     
     
       13. The invention of  claim 8 , wherein the array compares data from the first image with data from each of the series of subsequently acquired images by shifting one of the images with respect to another of the images. 
     
     
       14. The invention of  claim 8 , wherein the array compares data from the first image with data from each of the series of subsequently acquired images by shifting one of the images with respect to another of the images to determine differences in the comparisons between the data from the first image and data from each of the series of subsequently acquired images. 
     
     
       15. The invention of  claim 8 , wherein the array compares the data from the first image with the data from each of the series of subsequently acquired images by shifting one of the first or subsequently acquired images with respect to the other to determine differences in the comparisons between the data from the first image and the data from each of the series of subsequently images. 
     
     
       16. The invention of  claim 8 , wherein the array compares the data from the first image with data from one of the series of subsequently acquired images by shifting one of the first or subsequently acquired images with respect to the other to determine which shifted position best approximates an alignment of the features in the images. 
     
     
       17. The invention of  claim 15 , wherein the images are shifted in a nearest- neighbor fashion.   
     
     
       18. The invention of  claim 16 , wherein the light received at each photosensor in the array of photosensors is a pixel. 
     
     
       19. The invention of  claim 17 , wherein the images are shifted by one pixel. 
     
     
       20. The invention of  claim 18 , wherein the images are shifted to produce a nearest- neighbor comparison.   
     
     
       21. The invention of  claim 18 , wherein the images are shifted by more than one pixel. 
     
     
       22. The invention of claims  6  or  8 , further comprising:
   a transmitter for wireless transmission of a signal based on the relative motion.     
     
     
       23. The invention of  claim 22  wherein the transmitter further comprises:
   a wireless infrared transmitter.     
     
     
       24. The invention of  claim 23  wherein the signal comprises:
   data representing vectors indicating the relative motion.     
     
     
       25. The invention of  claim 22 , further comprising:
   a depressible key.     
     
     
       26. The invention of  claim 25 , wherein the depressible key further comprises:
   a cursor control key.     
     
     
       27. The invention of  claim 25 , wherein the depressible key further comprises:
   a return key.     
     
     
       28. The invention of  claim 25 , wherein the depressible key further comprises:
   a selection key.     
     
     
       29. The invention of  claim 25 , further comprising:
   one or more other keys to control other events.     
     
     
       30. The invention of  claim 25 , wherein the signal is continuously enabled. 
     
     
       31. The invention of  claim 5  further comprising:
   an exposure control for controlling exposure of the acquired images.     
     
     
       32. The invention of  claim 5  further comprising:
   automatic gain control of the images acquired.     
     
     
       33. The invention of  claim 32  wherein the automatic gain control is responsive to the comparisons of the data from the images. 
     
     
       34. The invention of claims  5 ,  6 ,  8 ,  9 ,  10 , or  23 , wherein the device is a computer mouse. 
     
     
       35. The invention of  claim 34  wherein the mouse is an optical mouse.