A Binary Coding Pattern for Virtual Absolute Encoder

Abstract

In this article, a binary coding pattern has been presented for the optical type virtual encoder. Unlike the traditional encoder, it can sense the direction, speed, and absolute position of the moving object. In this pattern, each combination of the binary number is represented by pulse transition, thus it is named as pulse transition code (PTC). In addition to the n-track binary code, it has dual clock track. So, in the absence of the external clock (i.e. reference) signal, one track can generate a clock signal during the rotation of the measured object. This signal is not only used for decoding the PTC pattern but also maintain the decoding rate of the receiver unit. Since the second clock track is placed 90 out-of-phase, thus it can sense the speed and direction of the moving object with respect to the prior clock track. Compared to the conventional binary coding pattern, its resolution varies four times per track number ((^)^). Eventually, to demonstrate the decoding methodology of the proposed coding pattern, a 2-bit PTC pattern is designed and developed an algorithm for a Microcontroller based decoder unit. The developed virtual encoder exhibits a satisfactory performance in laboratory conditions.