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

## TL;DR

SCALAR is a calibration method that simultaneously optimizes the kinematic and extrinsic parameters of a robot and laser sensor using simple planar and distance constraints, improving accuracy.

## Contribution

The paper introduces SCALAR, a novel calibration approach that uses minimal setup and nonlinear optimization to enhance robot and sensor calibration accuracy.

## Key findings

- Reduced mean tool position error from 0.44 mm to 0.19 mm
- Reduced maximum tool position error from 1.41 mm to 0.50 mm
- Effective calibration with simple flat plate setup

## 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.