Kinematic calibration of serial robots using low-cost tools

This paper presents the kinematic calibration of an open-chain robot using low-cost tools to measure the position of its end-effector. These tools include a smartphone video camera and an open-access online video analysis program. The methodology involves developing the robot's direct kinematic and identification models, executing motion trajectories, and recording them in two perpendicular planes. The videos extract the kinematic position variables required for the identification model. This section explains the calibration process, including axis alignment, reference points, and length measurements. It also details how the position variables can be obtained either manually or automatically using the video analysis program. Next, the dimensions of the robot's links are identified and validated by applying the calibrated dimensions to a trajectory different from the one used during calibration. When applied to an simulated ABB IRB120 robot, this methodology successfully identified the link dimensions with low errors. However, the precision achieved exceeded the specifications provided in the robot's catalog. The use of the video analysis program allowed for the automated determination of the robot's end-effector positions, significantly reducing human intervention in the calibration process. The proposed methodology is simple, cost-effective, and suitable for systems that do not require high precision.