【作者】 张丹；

【导师】 黄进；

【作者基本信息】 西安电子科技大学 ， 机械电子工程， 2008， 硕士

【摘要】 摩擦普遍存在于机电伺服系统中,它不但与接触表面间的正压力、相对速度相关,而且还与停滞时间相关,表现出摩擦记忆、变静摩擦等特性,从而导致了低速爬行,增大了稳态误差,降低了稳定性。为了消除或减小摩擦给系统带来的危害,提高伺服跟踪性能,本文研究了其控制补偿问题,主要内容如下:首先,以X-Y平台为研究对象,建立了基于动态LuGre摩擦模型的机电伺服系统模型,设计了非线性观测器,用于在线估计系统未知参数和受到的扰动;基于Lyapunov稳定性理论,应用反步积分方法,设计了反步控制器,保证了参数估值的收敛性和系统的全局稳定性。仿真结果表明,与传统的PID控制相比,反步积分自适应控制方法能够有效地对摩擦和其他干扰进行补偿,从而显著地减小了跟踪误差,增强了系统的鲁棒性。其次,针对LuGre摩擦模型,提出基于遗传算法的模型参数一步辨识方法,一次性辨识出摩擦模型中的静态参数和动态参数,克服了已有的两步辨识方法过程复杂、实验耗时等缺陷。更多还原

【Abstract】 Friction is widely present in servo systems. It depends not only on the normal forces in contact and relative velocity, but also on the lag time, leading to the friction memory and rising static friction, which may result in stick-slip in low speed, increasing steady-state errors and reducing stability of system. In order to eliminate or reduce the effect of friction, and increase the system performance, appropriate methods must be carried out. This dissertation focuses on the following work:Firstly, a mathematic model for X-Y table with dynamic LuGre friction model is established. And an nonlinear observer is designed to estimate the unknown friction parameters and other disturbances for adaptive friction compensation and disturbances rejection. A backstepping control law is derived with Lyapunov stability theory to ensure astringency of parameter estimation and global stability of servo systems with friction. Simulation results show that system robustness and tacking accuracy are improved with proposed method than that with traditional PID control.Finally, a one-step method for LuGre friction model parameter identification is presented. With the proper selected objective function, four static parameters and two dynamic parameters are obtained at one time. Thus, the complex and time-consuming constant velocity experiments, which are necessary for the two-step method, is avoided that makes the proposed method more practical.更多还原