Petrič Tadej, Žlajpah Leon
Department of Automatics, Biocybernetics and Robotics, Jožef Stefan Institute, Jamova cesta 39, 1000, Ljubljana, Slovenia.
Sci Rep. 2023 Oct 18;13(1):17804. doi: 10.1038/s41598-023-45156-6.
In this paper, we propose a novel approach for the kinematic calibration of collaborative redundat robots, focusing on improving their precision using a cost-effective and efficient method. We exploit the redundancy of the closed-loop kinematic chain by utilizing a spherical joint, enabling precise definition of the robot end-effector position while maintaining free joint motion in the null space. Leveraging the availability of joint torque sensors in most collaborative robots, we employ a kinesthetic approach to obtain constrained joint motion for calibration. An optimization approach is utilized to determine the optimal kinematic parameters based on measured joint positions and a constrained end-effector position defined by the spherical joint. The effectiveness of the proposed method is demonstrated and validated on the Franka Emika Panda robot, a 7-DoF robot. Results indicate a significant enhancement in absolute accuracy, with comparable performance to more expensive sensor systems such as optical measurement systems. Our approach offers a practical and cost-effective solution for improving the precision of collaborative robots.
在本文中，我们提出了一种用于协作冗余机器人运动学校准的新方法，重点是使用一种经济高效的方法提高其精度。我们通过利用球形关节来利用闭环运动链的冗余性，从而在保持关节在零空间中自由运动的同时，能够精确地定义机器人末端执行器的位置。利用大多数协作机器人中关节扭矩传感器的可用性，我们采用一种动觉方法来获得用于校准的受限关节运动。基于测量的关节位置和由球形关节定义的受限末端执行器位置，利用一种优化方法来确定最佳运动学参数。所提出的方法在7自由度的Franka Emika Panda机器人上得到了演示和验证。结果表明绝对精度有显著提高，其性能与诸如光学测量系统等更昂贵的传感器系统相当。我们的方法为提高协作机器人的精度提供了一种实用且经济高效的解决方案。
