考虑关节刚度的轻型模块化机器人标定方法
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摘要
轻型模块化机器人多采用谐波减速器驱动,谐波减速器的刚度低且具有高度非线性特征,因此难以采用线性参数辨识的方法获取关节刚度,故提出一种新的标定方法以提高机器人定位精度。首先,基于谐波减速器刚度特性曲线,建立机器人静刚度误差模型;然后利用激光跟踪仪测量机器人位置得到综合误差;之后,采用静刚度误差模型预估由于关节刚度引起的误差并从综合误差中分离;最后,采用最小二乘方法辨识实际D-H参数,结合刚度误差模型实时预估机器人末端误差并加以补偿。实验结果表明,该方法能够有效提高该类机器人的定位精度。
The lightweight modular robot is mostly driven by harmonic reducer,and the stiffness of the reducer is relatively low and highly nonlinear. Therefore it is difficult to obtain joint stiffness parameters by linear identification,so a new calibration method is proposed in this paper to improve position accuracy of the robot.Firstly,the static stiffness error model of the robot is established by the stiffness characteristic curve of the harmonic reducer; Then comprehensive position error of the robot is measured using a laser tracker; Next,the error due to joint stiffness is estimated using the static stiffness error model and separated from the comprehensive error; Finally,the actual Denavit-Hartenberg parameters are identified using the least squares method,and the terminal error of the robot is estimated and compensated in real-time combining the stiffness error model. The experimental results show that this method can improve positioning accuracy of the robot effectively.
The lightweight modular robot is mostly driven by harmonic reducer,and the stiffness of the reducer is relatively low and highly nonlinear. Therefore it is difficult to obtain joint stiffness parameters by linear identification,so a new calibration method is proposed in this paper to improve position accuracy of the robot.Firstly,the static stiffness error model of the robot is established by the stiffness characteristic curve of the harmonic reducer; Then comprehensive position error of the robot is measured using a laser tracker; Next,the error due to joint stiffness is estimated using the static stiffness error model and separated from the comprehensive error; Finally,the actual Denavit-Hartenberg parameters are identified using the least squares method,and the terminal error of the robot is estimated and compensated in real-time combining the stiffness error model. The experimental results show that this method can improve positioning accuracy of the robot effectively.
引文
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[15]戴孝亮.工业机器人运动学标定及刚度辨识的研究[D].广州:华南理工大学,2013Dai X L.Study on kinematic calibration and stiffness identification for industrial robots[D].Guangzhou:South China University of Technology,2013(in Chinese)
[2]南小海.6R型工业机器人标定算法与实验研究[D].武汉:华中科技大学,2008Nan X H.Research on 6R industrial robot calibration algorithm and experimental verification[D].Wuhan:Huazhong University of Science and Technology,2008(in Chinese)
[3]Nubiola A,Bonev I A.Absolute robot calibration with a single telescoping ballbar[J].Precision Engineering,2014,38(3):472-480
[4]张晓平.六自由度关节型机器人参数标定方法与实验研究[D].武汉:.华中科技大学,2013Zhang X P.Research on 6R articulated robot calibration methods and experiments[D].Wuhan:Huazhong University of Science and Technology,2013(in Chinese)
[5]李定坤,叶声华,任永杰,等.机器人定位精度标定技术的研究[J].计量学报,2007,28(3):224-227Li D K,Ye S H,Ren Y J,et al.Research on robot's positioning accuracy calibration[J].Acta Metrologica Sinica,2007,28(3):224-227(in Chinese)
[6]齐飞,平雪良,刘杰,等.考虑关节柔性误差的机器人参数辨识方法研究[J].机械科学与技术,2017,36(4):512-518Qi F,Ping X L,Liu J,et al.A robot's parameter identification method with joint flexible errors taken into account[J].Mechanical Science and Technology for Aerospace Engineering,2017,36(4):512-518(in Chinese)
[7]Lim H K,Kim D H,Kim S R,et al.A practical approach to enhance positioning accuracy for industrial robots[C]//ICROS-SICE International Joint Conference.Fukuoka,Japan:IEEE,2009:2268-2273
[8]Kircanski N M,Goldenberg A A.An experimental study of nonlinear stiffness,hysteresis,and friction effects in robot joints with harmonic drives and torque sensors[J].The International Journal of Robotics Research,1997,16(2):214-239
[9]Kamali K,Joubair A,Bonev I A,et al.Elasto-geometrical calibration of an industrial robot under multidirectional external loads using a laser tracker[C]//Proceedings of2016 IEEE International Conference on Robotics and Automation.Stockholm,Sweden:IEEE,2016:4320-4327
[10]Zhou J,Kang H J.A hybrid least-squares genetic algorithm-based algorithm for simultaneous identification of geometric and compliance errors in industrial robots[J].Advances in Mechanical Engineering,2015,7(6)
[11]黎田.柔性关节机械臂及其运动学标定和振动抑制的研究[D].哈尔滨:哈尔滨工业大学,2012Li T.Research on flexible joint robot and its kinematic calibration and vibration suppression research[D].Harbin:Harbin Institute of Technology,2012(in Chinese)
[12]周军,余跃庆.考虑关节柔性的模块机器人动力学参数辨识[J].机器人,2011,33(4):440-448Zhou J,Yu Y Q.Dynamic parameter identification of modular robot with flexible joints[J].Robot,2011,33(4):440-448(in Chinese)
[13]任永杰,邾继贵,杨学友,等.利用激光跟踪仪对机器人进行标定的方法[J].机械工程学报,2007,43(9):195-200Ren Y J,Zhu J G,Yang X Y,et al.Method of robot calibration based on laser tracker[J].Chinese Journal of Mechanical Engineering,2007,43(9):195-200(in Chinese)
[14]王品,廖启征,庄育锋,等.一般7R串联机器人标定的仿真与实验[J].机器人,2006,28(5):483-487,494Wang P,Liao Q Z,Zhuang Y F,et al.Simulation and experimentation for calibration of general 7R serial robots[J].Robot,2006,28(5):483-487,494(in Chinese)
[15]戴孝亮.工业机器人运动学标定及刚度辨识的研究[D].广州:华南理工大学,2013Dai X L.Study on kinematic calibration and stiffness identification for industrial robots[D].Guangzhou:South China University of Technology,2013(in Chinese)