非正交可重组机床的控制外文翻译(编辑修改稿)

非正交可重组机床的控制外文翻译(编辑修改稿)内容摘要：

signed a special crosscoupling controller. In the present paper, we would like to explain some aspects of the controller design. This design of a new crosscoupling controller for the 3axes of motion gives insight to the system behavior under external disturbances. Indepth Error The indepth error is typical to the characteristics of our nonorthogonal machine. In order to cut the workpiece at a predetermined depth, the bined motion of both Y and Zaxis must be controlled. As a result of the position errors of the servomotor drives due to the external disturbances on each axis the indepth error is generated. This error may affect significantly the quality of the surface finish. The indepth error is described in describes the linear relation between the error ponents in the Y and Z directions. It is important to understand that this error is not only time dependent but also depends on the machine reconfiguration angular position. For each angle of spindle axis positioning, the controller will apply different value of Czy in equation 3 Controllers Design In traditional orthogonal CNC machines, the crosscoupling control strategy effectively reduces the error between the predetermined tool path and the actual tool path. In a twoaxis contouring system, the Xaxis servodrive receives two inputs: one a traditional input from an Xaxis servo controller that reduces Ex (the axial position error along the X direction) and another input from the crosscoupling controller to reduce rx (the X ponent of the contour error). Similarly, the Yaxis plant receives two inputs. The additional inputs to each axis are used to decrease the contour error in the normal direction represented by r The objective of this paper is to suggest a suitable crosscoupling control strategy for both the contour and indepth errors. Three controllers are examined: a symmetric crosscoupling (SCC) controller, the symmetric crosscoupling controller with additional feedforward (SCCFF), and a nonsymmetric crosscoupling controller with feedforward (NSCCFF). a Controllers Structures. The detailed structure of the three controllers is illustrated The basic structure is to have two standard crosscoupling (CC) controllers, one for the contour error in the XYsubsystem with a gain Gr and the other for the indepth error in the YZsubsystem with a gain Gz. Section 4b includes a discussion on the values of Gr and Gz. The indepth crosscoupling controller has the same basic control structure as the contour crosscoupling controller. In addition, a feedforward term may be used to inform the Zaxis about the additional Yaxis input caused by the contour crosscoupling controller. Knowing this information in advance, the Zaxis can pensate for the movement of the Yaxis in order to reduce the indepth error. The differences among the three proposed controllers are: (a) the presence or absence of a feedforward term (In the SCC controller, the Kff block does not exist), and (b) a difference in the direction of the controlling error (in the NSCCFF controller, Czy is zero). If the feedforward term exists, Kff in Figure 6 can be expressed as follows The tracing error estimation gains, Crx, Cry, Czy, Czz are given in Equations (1) and (2). The symmetric crosscoupling (SCC) controller uses the contour crosscoupling controller between the X and Yaxis and the indepth crosscoupling controller between the Y and Zaxis. The contour crosscoupling controller decreases the contour error by coupling the X and Yaxis movements while the indepth crosscoupling controller pensates the indepth error by coupling the Y and Zaxis movements. The Yaxis receives one output from each crosscoupling controller。 Ury and Uzy. As briefly explained in the previous section, Ury and Uzy may be in conflict with each other and the resulting control action does not necessarily decrease both the contour and the indepth error. This is the main drawback of the SCC controller and it will be further investigated in the stability section. The symmetric crosscoupling feedforward (SCCFF) controller has the same structure as the SCC controller, but includes an additional feedforward term. This feedforward term gives the Zaxis information about the movement of the Yaxis. In other words, when an output from the contour crosscoupling controller is applied to the Yaxis, this additional input is fed to the Zaxis in order to reduce the indepth error from that additional input to Yaxis. Even though the SCCFF controller improves the performance of the system by adding a feedforward term, the conflict between the crosscoupling controllers still exists. Again, this characteristic will be discussed in more detail in the stability section. This is the motivation for introducing the next controller. The nonsymmetric crosscoupling feedforward (NSCCFF) controller is suggested in order to remove the coupling between the crosscoupling controllers. Even though the indepth error depends on the performance of the Y and Zaxis, this error is always parallel to the Zaxis movement. Using this characteristic we convert the controller to a master (Y)slave (Z) operation in which the controller moves only the Zaxis to decrease the indepth error. Namely, the coupling between the contour crosscoupling controller and the indepth crosscoupling controller is removed in the NSCCFF controller. Therefore, Yaxis servo drive receives only one output from the crosscoupling controllers. As will be shown later this controller has the best performance. 4 Controllers Stability Analysis The RMT system has tightly coupled axes and contains timevarying sinusoidal parameters. In order to simplify the stability analysis, the following assumption was ma。