伺服关节驱动的柔性臂系统耦合动力学模型辨识与实验

针对整个伺服关节驱动的柔性机械臂系统,在考虑其机电、刚柔耦合特性的基础上,理论上进行了动力学建模。分析了包含直流伺服电机、谐波减速器以及伺服驱动器的伺服关节的驱动及摩擦特性,对实验中测到的电机匀速正反转数据进行线性拟合,得到了关节驱动模型中的库伦摩擦力常数和黏滞摩擦力系数。分别建立了从伺服电机驱动电压到光电编码器检测的电机转角、从伺服驱动电压到代表柔性臂振动的应变桥路输出之间的理论传递函数,以伪随机二进制序列为激励信号,通过实验辨识得到了此对应伺服关节柔性臂转动与振动耦合以及机电耦合的两个传递函数,在伪随机和正弦信号激励下,辨识得到的传递函数模型与实际结构的转动位移和振动响应具有较高的一致性。从而得到了伺服关节驱动的柔性臂系统刚柔耦合、机电耦合的动力学模型。

Coupling dynamic modeling of a flexible manipulator driven by servo joint and test recognition

Aiming at a flexible manipulator system driven by servo joint, considering its electro-mechanical and rigid-flexible coupled characteristics, its dynamic model was established theoretically. Driving and friction characteristics of the servo joint containing a DC servo motor, a harmonic reducer and a servo driver were analyzed. By linearly fitting constant speed forward and reverse rotation data of the motor, Coulomb friction force constant and viscous friction force coefficient in the servo joint driving model were obtained. Then, the theoretical transfer function from the driving voltage of the servo motor to the motor rotating angle detected by a photoelectric encoder and the other from the driving voltage of the servo motor to output of strain bridge circuit representing the flexible manipulator’s vibration were built. Taking pseudo-random binary sequence as excitation signals, two transfer functions corresponding to rotation-vibration coupling and electro-mechanical coupling of the flexible manipulator were acquired through test recognition. Test results showed that under pseudo-random and sine signal excitations, the two identified transfer function models are better consistent to the two theoretical ones;responses calculated with the two theoretical transfer function models agree well with rotation displacement responses and vibration ones of the actual structure;so the correctness of the established coupling dynamic model of the flexible manipulator system driven by servo joint is verified.