Abstract
Optimum design of the position control system using radiation relay is presented in this paper.
As the controlled object (a plate with uniform thickness) covers the radiation detector from one side to the other with constant velocity, the amount of incident radiation is changed. This radiation is scaled with constant scaling time and the radiation relay acts and stops the motion of the plate at the first time when the output of the scaler reaches the settling value.
The problem of calculating the mean value and variance of the position where the object plate is stopped is a kind of the first passage time problem and this calculation is troublesome and inconvenient for analysis.
In this paper the simple apploximate equations for obtaining the mean value and standard deviation are presented. These equations can be simplified using the total counts while the plate goes across the window (<nd>·D2B/U).
U: Velocity of the controlled object (cm/s).
<nd>: Mean counting rate per unit aria (counts/s cm2).
D: Length of the window of radiation detector (cm).
B: Width of the window (cm).
By these apploximate equations the optimum scaling time, optimum length of the window, and necessary mean counting rate of radiation are obtained to minimize the standard deviation of the stopping position less than the given value. The mean stopping position can be also obtained.
The limit of the application of these apploximate equations is also presented.
