机器人的非线性扰动观测器设计英文文献和中文翻译(3)

compliant surface and a force control scheme is needed to

guarantee good system performance。 Therefore, a force sensor is needed to measure these contact forces。 Disturbance observers

can be employed in these applications when there is no sensor available for measuring torques and forces。 For instance, distur-

bance observers have been employed successfully in sensorless

force control (Eom, Suh, Chung, & Oh, 1998; Katsura, Matsumoto, & Ohnishi, 2003; Lee, Chan, & Mital, 1993; Shimada, Ohishi, Kumagai, & Miyazaki, 2010)。 Another potential application of disturbance

observers can be in micro/nano manipulation tasks, e。g。, microinjec- tion to introduce foreign materials into biological cells (Tan, Sun, Huang, & Chen, 2008), where there is a lack of small enough force sensors with good precision and signal to noise ratio (Rakotondrabe, Clevy, Rabenorosoa, & Ncir, 2010)。

Recently, a new system has been developed to teach motion to robots in order to improve their dexterity (Katsura, Matsumoto, & Ohnishi, 2010)。 The so-called shadow robot system consists of two identical robots。 The robots are controlled by bilateral acceleration control schemes based on a disturbance observer。 One robot is guided by a human operator in teaching motion mode and the other robot is unconstrained and imitates the motion of the constrained robot with the same position, velocity and acceleration。 It is desired that the human operator’s pure force is extracted from the con- strained robot。 In order to ﬁnd the operator’s force, a disturbance observer is employed to estimate the disturbance forces such as friction and gravity in the unconstrained robot。 The disturbance forces acting on the constrained and the unconstrained robots are the same。 The human operator’s force is then estimated by sub- tracting the disturbance forces acting on the unconstrained robot from the total force in the constrained robot。 As a result, the shadow robot system observes the human force in the presence of gravity and friction without a need for force sensors。 Lastly, industrial robots

employ fault detection systems in order to determine if a fault, such as a collision or an abrupt increase in reaction forces, has occurred in the system。 Disturbance observers have been used for fault detec- tion in a number of robotic applications (Chan, 1995; Ohishi & Ohde, 1994; Sneider & Frank, 1996)。 Table 1 summarizes the most important applications of disturbance observers in robotics。

A considerable part of the existing literature on disturbance observer design for robotic applications uses linearized models or linear system techniques (Bickel & Tomizuka, 1995; Kim & Chung, 2003; Komada, Machii, & Hori, 2000; Liu & Peng, 2000)。 In order to overcome the linear disturbance observer limitations for the highly nonlinear and coupled dynamics of robotic manipulators, Chen, Ballance, Gawthrop, and O’Reilly (2000) proposed a general nonlinear disturbance observer structure for nonlinear robotic manipulators。 Using Chen et al。 NDOB, the observer design

problem reduces to ﬁnding an observer gain matrix such that disturbance tracking is achieved。 However, Chen et al。 could ﬁnd

such a gain matrix for a 2-link planar manipulator with revolute

joints。 Later, Nikoobin et al。 generalized Chen’s solution to n-link 机器人的非线性扰动观测器设计英文文献和中文翻译(3):http://www.youerw.com/fanyi/lunwen_89868.html