三维粗糙度参数算术平均偏差与均方根偏差的规律研究

使用ADE公司的非接触式表面三维形貌仪对粗糙度标准样板进行系统测试,依据测试结果分析了三维粗糙度参数算术平均偏差与均方根偏差的规律。结果表明:三维与二维参数具有较强的延续性;Sa相对Ra具有明显的优越性,对于周期性表面Sa和Ra数值基本一致,对于随机性较强的表面Sa明显大于Ra;Sq相对Sa能更加细致地反映表面的随机特征,应优先选用。Sa、Sq将来作为标准使用时,其数值规律应该针对不同类型表面区别对待。     

Experimental results on discrete-time nonlinear adaptive trackingcontrol of a flexible-link manipulator

The aim of this paper is to develop and implement a nonlinear adaptive control scheme for a single-link flexible manipulator. The controller is designed based on a discrete-time nonlinear model of the arm. The model is derived by using the forward difference method (Euler approximation). The output redefinition concept is then used so that the associated zero dynamics corresponding to the new output is guaranteed to be exponentially stable. An indirect adaptive linearizing controller is developed for the resulting minimum phase system where the "payload mass" is assumed to be unknown but its upper bound is assumed to be known a priori. The performance of the adaptively controlled closed-loop system is investigated by both numerical simulations and experimental results. The proposed controller is also compared experimentally with those of nonadaptive feedback linearization and conventional proportional derivative (PD) control strategies.     

An indirect adaptive control for fully feedback linearizable discrete-time non-linear systems

An indirect adaptive control for a discrete-time non-linear system that is fully input–output linearizable is developed. The unknown parameters of the system are identified by using a multi-output RLS algorithm. Based on the certainty equivalence principle, the estimated parameters are then utilized in the controller design. Stability of the adaptively controlled closed-loop system is shown by using the Lyapunov method. Numerical simulations are included to illustrated the performance of the proposed strategy. © 1997 John Wiley & Sons, Ltd.