A wide speed range and high precision position and velocity measurements chip with serial peripheral interface

This paper presents a VLSI chip, with a serial peripheral interface (SPI), that obtains position and velocity measurements from incremental optical encoder feedback. It combines period and frequency countings to provide velocity estimates with good dynamic behavior over a wide speed range (10 Hz–50 MHz). 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. It is compact with lower power consumption when 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 2P3 M 0.5 μm CMOS process and consumes 4.82 mW power with active area of 0.45 mm2.