FPGA-based Servo Control IC for X-Y Table

Abstract

The new generation of field programmable gate arrays (FPGAs) technology enables to be embedded a processor to construct an SoPC (system-on-a-programmable-chip) developing environment. Therefore, this study presents a servo control IC for X-Y table using this SoPC technology. In this proposed servo control IC, there are two modules. One module performs the functions of the motion trajectory and two-axis position controller. The other module performs the functions of current vector control of motor drives for two PMSMs (permanent magnet synchronous motors). The former is implemented by software using Nios II embedded processor due to the need of the complicated control algorithm and low sampling frequency control (motion trajectory & position control: less than 1kHz). The latter is implemented by hardware using PLD (programmable logic device) in FPGA due to the need of high sampling frequency control (current loop: 16kHz, PWM circuit: 4~8MHz) but simple computation. Furthermore, to improve the control accuracy of the table positioning, a full closed-loop control, which the signal of linear encoder is feed-backed for position control, is considered. As this result, the use of SoPC technology can make the servo controller of X-Y table more compact, high performance and cost down.