Stablizied and Rotating Mechanism of 2D Laser Scanner for 3D Point Cloud Reconstruction

Abstract

This research presents a stabilizing and rotating mechanism for laser scanner; thus 3D cloud points could be reconstructed. Design and development of a vertical scanning system and a roll-motion stabilizing system for laser point-cloud data, measured radial distance horizontally, are implemented. By using an encoder to feedback a roll angle, the first DC servo motor with a PI controller can assist stabilizing horizontal point-cloud data. A four-bar linkage mechanism, driven by the second DC motor and controlled by a feedforward controller with Inertial Measurement Unit (IMU) pitch-angle feedback, could generate $\pmb{\pm 16.5^{\circ}}$ up-and-down pitching motion of the laser scanner. Both digital feedback controllers of two motors are developed in an Arduino microcontroller. Kinematics model of the four-bar linkage mechanism are derived and simulated for a design purpose. Experimental tests of the first motor, controlled by the PI-controller, reveal robustness against external-force disturbances, acting on the laser scanner, and demonstrate a roll-motion counterweight of the mechanism base. In additions, experiments of the second motor with the feedforward controller can compensate for gravity to achieve periodical cycles of the four-bar linkage motion. Reconstructed 3D point-cloud surface from laser 2D cloud points can provide accurate horizontal width and smooth-continuous height of measured indoor wall.