Method For Industrial Robot Tracking And Navigation Based On Time-Of-Flight Laser Rangefinding And The Position Sensitive Detection Technique

摘要

A system is proposed which can be used to track a moving machine or vehicle and determine its 3D coordinates continuously and accurately within a short measuring time. The system includes a stationary servo-controlled measuring head and optical reflectors attached to the robot or vehicle to be monitored. The measuring head consists of a time-of-flight laser rangefinder and angle encoders. Tracking is accomplished by illuminating the cooperative target with a laser diode or LED and focusing the reflected light on the surface of a position-sensitive detector (PSD). The latter acts as a null detector and its signals are used to drive the servomotors of the measuring head. Both the emitter and the PSD are located in the measuring head. Preliminary tests show that a tracking resolution of about 200 Arad (FWHM) is achievable in tracking over a measurement range of 100 m. The transmitter ouput beam produced by a cw laser diode collimator pen and a single positive lens (f=300 mm) has an average ouput power of 8 mW and a divergence of 14 mrad. The detector in these tests consisted of a four quadrant PSD located near the focal plane of a positive lens (Φ=50 mm, f=200 mm) and associated envelope detection and signal processing electronics with a bandwidth of 100 Hz. The target used was a sphere (Φ=15 cm) constructed of a highly reflective tape.