文档介绍：羅致卿, 1995, "彈性化與組合化之伺服控制系統," 國科會補助專題研究計畫成果報告, 計畫編
號:NSC 83-0401-E-035-002, 84-2212-E-035-011
1. INTRODUCTION
. Research Objectives
To achieve high precision required in future contouring (or tracking) applications, accurate
servo controllers are continuously being sought. In contouring applications, the machines (.,
machine tools, robotic manipulators) are driven to track a desired contour. The contour tracking,
however, is generally not perfect and results in contour errors. The term "contour error" is used to
denote the ponent orthogonal to the desired trajectory (., the deviation from the desired
path). The process for a two-axis machine to track a desired contour is depicted in Fig. . As can
be seen, the contour error, rather than the axial errors, is our main concern during the tracking. In
addition to the contour error, the tracking lag, the overshoot, and the positioning error at the end of
the tracking are the other concerns. Fig. depicts these concerns in the view that is along the
tracking path. Moreover, Fig. shows unqualified results according to a large overshoot and a
large tracking lag in tracking a corner that is bination of two consecutive contours.
end position
overshoot
positioning error
Y-axis
target position
X-axis
[R , Ryx ]
Ey
Desired path
Ex
start E c
position [P xy , P ]
Actual path
E c : contour error
E x , Ey : axial errors
[Rx , Ry ] : instantaneous reference position
[Px , P y ] : instantaneous actual position
Fig. : The errors in tracking a 2D contour.
1
overshoot positioning
error
tracking lag
Time
Fig. : The tracking lag, the overshoot, and the positioning error in the
view that is along the tracking path
second contour
large overshoot
large tracking lag
first contour
Fig. : Poor tracking results caused by large overshoot or tracking lag
in a corner tracking.
In order to maintain