基于标准球距离约束的工业机器人参数标定

Calibration of Industrial Robot Parameters Based on Standard Ball Distance Constraints

针对工业机器人绝对定位精度偏低,在工业应用中受到一定的限制的问题,提出了一种新型基于标准球距离约束的工业机器人参数标定方法。首先采用MDH模型建立机器人运动学模型;其次将接触式测头安装在工业机器人的末端法兰盘上,搭建了一个三角标定平台,平台上刚性连接了3个直径为25.4 mm的标准球,每2个球之间的理论的球心距为300 mm,用接触式测头分别探测3个标准球面上的点,并记录相应关节角的值;最后,通过最小二乘拟合得到标准球的球心坐标,与三坐标测量机测得的实际球心距进行距离约束,并采用Levenberg-Marquardt算法求得运动学参数误差。共进行5个平台方向的实验,并用另外5个平台方向的数据进行误差补偿验证。实验结果表明:平均球心距偏差从2.6812 mm减小到0.5694 mm,标准偏差从0.6738 mm减小到0.1407 mm。

Aiming at the problem that the absolute positioning accuracy of current industrial robots is low and limited in industrial applications,based on standard ball distance constraint,a new method for industrial robot parameter calibration was proposed.Firstly,the MDH model was used to establish the robot kinematics model.Secondly,the contact probe was mounted on the end flange of the industrial robot,and a triangular calibration platform was built.The platform was rigidly connected with three standard balls with a diameter of 25.4 mm.The theoretical center of the ball between each two balls was 300 mm.The probe was used to separately detect the points on the three standard spheres,and record the values of the corresponding joint angles.Finally,the spherical center coordinates of the standard sphere were obtained by least squares fitting,and the distance was constrained from the actual spherical center distance measured by the coordinate measuring machine,and the kinematic parameter error was obtained by using the Levenberg_Marquardt algorithm.A total of 5 platform orientation experiments were performed and error compensation verification was performed using data from 5 other platform directions.The experimental results show that the average spherical center distance deviation decreases from 2.6812 mm to 0.5694 mm,and the standard deviation decreases from 0.6738 mm to 0.1407 mm.