SCALAR: Simultaneous Calibration of 2D Laser and Robot Kinematic Parameters Using Planarity and Distance Constraints

Abstract

In this paper, we propose SCALAR, a calibration method to simultaneously calibrate the kinematic parameters of a 6-DoF robot and the extrinsic parameters of a 2D Laser Range Finder (LRF) attached to the robot's flange. The calibration setup requires only a flat plate with two small holes carved on it at a known distance from each other, and a sharp tool-tip attached to the robot's flange. The calibration is formulated as a nonlinear optimization problem where the laser and the tool-tip are used to provide planar and distance constraints, and the optimization problem is solved using Levenberg-Marquardt algorithm. We demonstrate through experiments that SCALAR can reduce the mean and the maximum tool position error from 0.44 mm to 0.19 mm and from 1.41 mm to 0.50 mm, respectively.Note to Practitioners-Many industrial robotic applications require the robotic system to be calibrated in order to achieve the demanded accuracy. Unfortunately, existing calibration processes are often cumbersome or require expensive measurement systems. This paper presents a novel calibration method to calibrate simultaneously a 6-DoF industrial robot and a 2D laser scanner attached to the robot's flange. The method only uses the data from the robot and the laser, so there is no need for external measurement systems. The laser scanner can also be used after the calibration for subsequent robot tasks such as scanning a workpiece to accurately determine its location. The calibration setup only requires a flat plane and a sharp tool-tip attached on the robot's flange. The proposed method is easy to deploy and is more cost-effective than existing calibration methods.