ja- 
In a simplistic manner, the dynamic performance can be tested by plot- 
ting curves of various sizes and shapes. The simplest one being a circle, 
the plotting accuracy of a circle can be tested. The actual (true and pre- 
dicted) coordinates of the points can be computed by using the following 
relations: 
X Te. COS 9 
P 
= Tr . Sin 6 
Yo n 
where Xp? Yo are the predicted coordinates of the plotted points 
r is the radius of the input circle 
0 is the angle of a radial direction with the x-axis on plot. 
The errors in x, y and planimetry (e , e and e , respectively) can be 
computed by using x og” P 
ex p^ x 
e = - 
es 7p 
e = # (e 2 2, 
p X y 
where Xps Yp are the digitized (and plotted) locations of the points in 
x and y. 
Such a study made by using 30 points along the perimeter of a circle 
gave the following results: 
e. (max) = 177 um es (max) = 537 um 
ec (min) = 6 um e (min) = 25 um 
o. = +113 um Sy = +364 um 
One may note that by the dynamic process one refers to the information 
flow where the signals are represented by differential movements. These 
values may be compared with those in Table 1 to obtain the static to dynamic 
ratio (see Table 2). 
TABLE 2 
Accuracy performance tests on Stereotope (modified) 
  
  
  
Std. Mode of operation | Ratio 
error Static Dynamic (Dynamic/Static) 
in 
X 2l um 113 um 5.4 
yo 25 um 364 um 14.6 
p 33 um 381 um 11.5 
  
221