Incremental Encoder Based Position and Velocity Measurements VLSI Chip with Serial Peripheral Interface

Abstract

This paper presents an incremental optical encoder based position and velocity measurements VLSI chip with a serial peripheral interface (SPI). It combines period and frequency countings to provide velocity estimates with good dynamic behavior over a wide speed range. By sensing the velocity of the encoder, it reserves the computational power of a supervisory microcontroller, and subsequently enhances the performance of the total system. Furthermore, multiple copies of the velocity encoder can access the behavior of multiple motors in parallel. It is compact with lower power consumption compared to traditional FPGA implementations. Although designed for use in the control unit of a medical robot with 34-axes and tight space and power constraints, it can be readily used in other applications. It is implemented in a 2P3M <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.5μm</i> CMOS process and consumes 4.82mW power with active area of <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.45mm²</i> .