Precision control and performance of new-generation integrated fiber positioners for LAMOST

Abstract

An improvement project of LAMOST will be implemented soon. To improve the observation accuracy and spectral acquisition rate, a new integrated fiber positioner was designed for the new robotic Focal Plane System. This paper designs the drive system for the integrated fiber positioner, and introduces the mechanical, electronic and software design in detail. We also built a vision measurement platform with a telecentric lenses to test the position performance. The fiber positioner positions the fiber to target by first blind positioning and multiple position corrections. After the positioner completes the first blind move, the camera takes the fiber image and calculates the offset between the actual position of the fiber from its target position. Then, the drive system controls the fiber positioner move according the offset value to correct the fiber position. We achieve the final accuracy through iterative position corrections. Experimental results show that both the drive system and the fiber positioner have reliable performance and high efficiency. With a first blind move inside of its workspace, the positioner can position the fibers with a planar precision better than 100um, the position error is less than 10um after the second correction and the RMS error is less than 3um.

Ultra-low power drive system design for fiber positioner robot

“…Due to the limitations of the fiber positioner robot tail volume and space, the width of the designed driver board is 13.7mm, the length is 11cm, and the PCB adopts a four-layer board scheme. The main function of the driver board is to receive the control signals from the CAN bus or serial port, parse the control signals, and drive the center and eccentric axis motors on the fiber positioner robot through the driver circuit 6 . The hardware circuit mainly includes: main control MCU module, DC-DC power supply module, CAN bus communication module, motor driver chip and peripheral circuit module, the electrical design block diagram is shown in Figure 3.…”