48 | 
  
249 
5 THE FEEDBACK STEREOPSIS SYSTEM 
Figure 1 is a simplified diagram of a feedback stereopsis system for industri- 
al robots. À system for photogrammetry would need a Y disparity system and 
computational elements for analytical functions not required in a robot 
stereopsis system. 
The second performance lim- — : | 
itation mentioned in the /N 
introduction (poor utiliza- WOW Space 
tion of low contrast | gr \ 
imagery) is corrected by / \ 
the video processors. 
First, they equalize the 
effectiveness of highlight 
and shadow detail by taking 
the logarithm of the video 
signal. Second, they elim- 
inate the fixed noise aris- 
ing out of variations in 
the pixel to pixel sens- 
itivity and dark current of 
the sensor arrays. Third, 
they adjust the brightness 
range of the video signals 
to match the capacity of 
the digital video channels. 
Another function of the 
video processors, not 
connected with contrast 
problems, is to detect and 
eliminate the disturbing 
effect of specularities on 
correlation. 
Binocular 
Camera Set 
           
  
       
       
    
    
      
  
   
     
     
  
     
  
    
   
  
VIDEO 
PROCESSOR 
ARRAY 
DRIVERS 
VIDEO 
PROCESSOR 
    
     
  
  
DISPLACEMENT 
DELAY RAM 
  
   
etu 
GN 
FANT 3 x 
HANGE Transformation 
Delay 
i Unit 
J 
ISPLACEMENT 
ELAY RAM 
   
X DISPARITY 
DISCRIMINATOR 
  
   
+ 
DELAY RAM 
B 
Synchronous 
Gestalt 
DELAY RAM Accumulator 
A 
ere nep 
The Transformation Delay 
Unit (TDU) transforms the 
images by shifting each pix- 
el of each image in the X 
| direction in response to a 
| dx control signal, the pix- Fused Change Coordinate ; 
els of the left and right Video Output Output 1973 
images are shifted equally 
but in opposite directions. 
   
Geometric 
Parameters 
OUTPUT 
COMPUTER 
  
   
  
SCANNING 
GENERATOR 
  
  
  
Figure 1 ROBOT STEREOPSIS SYSTEM 
The X Disparity Discriminator (XDD) senses the magnitude and sign of local x 
disparity and delivers a string of local dx signals to the- 
Synchronous Gestalt Accumulator (SGA) which stores the dx values for each 
pixel of one entire frame or field of view. During the scanning of the each 
frame the stored dx signal is fed back to the TDU as a control signal to shift 
the pixels in the X direction to reduce X disparity. Residual dx is then 
sensed by the XDD and the resultant dx signal is delivered to the SGA where it 
is added to the previous dx value for the appropriate pixel. 
After a few iterations all X disparity between the inputs to the XDD is 
eliminated and the output of the XDD falls to zero. The output of the SGA then 
contains all of the dx data for the entire window matrix in serial form.