Abstract
To establish a delta operator technique in fixed-point arithmetic, the previous report proposed a modified delta operator and form named Variable Modulation Method (VMM). The principle is based on the methodology of PWM. In the present paper, it is aimed to apply VMM to a PID controlling system and verify the availability of VMM experimentally. First, the problem of the conventional shift and delta operation in fixed-point arithmetic is described. Next, the outline of VMM for solving this problem is described. Furthermore, the implementation procedure of a PID control algorithm based on the shift and VMM form is shown, respectively. Finally, both methods are compared experimentally on the position control of the DC motor. In case of a 16 bit word-length, responses in using both forms are not drastically different from those in using floating-point arithmetic. In case of an 8 bit word-length, step and ramp responses in using the VMM form are almost similar to those in using floating-point arithmetic. Thus, the availability of VMM was made clear in case of a short word-length.
