复杂金属接缝焊接机器人双臂非线性抖动控制方法研究

Research on nonlinear dual-arm jitter control of complex metal joint welding robot

焊接机器人机械臂关节中的死区、间隙等非线性环节会导致系统的动态行为复杂化,各个关节和执行器之间存在运动耦合关系,导致关节在局部区域产生非线性抖动,从而出现控制误差。为此,提出复杂金属接缝焊接机器人双臂非线性抖动控制方法。构建焊接机器人运动坐标系,得到终端机器人转换矩阵,实现对双臂关节的复杂非线性运动耦合分析;考虑关节运行中存在死区、间隙等非线性环节,引入线性函数输出关节实际旋转角度;将旋转角度作为径向基函数神经网络的输入,并利用拉格朗日定律将转换矩阵转化为带有机械臂角位移、角速度和角加速度,并将其引入至非线性积分滑动模态控制方程中,以补偿机械臂的摩擦力力矩、离心力矩阵和重力,以减小非线性抖动,最终得到自适应控制结果,从而减小控制误差。通过实验可知,所提方法能够处理焊接过程中固有的不确定性、非线性和外部干扰,提高焊接精度和稳定性,有助于提升焊接质量和一致性。

The nonlinear links such as dead zone and gap in the joints of the manipulator of the welding robot will complicate the dynamic behavior of the system.There is a motion coupling relationship between each joint and the actuator,which leads to nonlinear jitter of the joint in the local area,resulting in control errors.For this reason,a nonlinear dual-arm jitter control method for complex metal joint welding robot is proposed.The motion coordinate system of welding robot is constructed,the transformation matrix of terminal robot is obtained,and the complex nonlinear motion coupling analysis of both arms joint is realized.Considering the existence of nonlinear links such as dead zone and clearance in joint operation,a linear function is introduced to output the actual rotation angle of the joint.The rotation angle is taken as the input of the radial basis function neural network,and Lagrange′s law is used to transform the conversion matrix into the angular displacement,angular velocity and angular acceleration of the robot arm,which are introduced into the nonlinear integral sliding mode governing equation to compensate the friction torque,centrifugal force matrix and gravity of the robot arm,so as to reduce the nonlinear jitter,and finally obtain the adaptive control result.Thus the control error is reduced.The experiment shows that the proposed method can deal with the inherent uncertainty,nonlinearity and external interference in the welding process,improve the welding accuracy and stability,and help to improve the welding qualityand consistency.