  We numerically study trajectories of spiral-wave-cores in excitable systems
modulated proportionally to the integral of the activity on the straight line,
several or dozens of equi-spaced measuring points on the straight line, the
double-line and the contour-line. We show the single-line feedback results in
the drift of core center along a straight line being parallel to the detector.
An interesting finding is that the drift location in $y$ is a piecewise
linear-increasing function of both the feedback line location and time delay.
Similar trajectory occurs when replacing the feedback line with several or
dozens of equi-spaced measuring points on the straight line. This allows to
move the spiral core to the desired location along a chosen direction by
measuring several or dozens of points. Under the double-line feedback, the
shape of the tip trajectory representing the competition between the first and
second feedback lines is determined by the distance of two lines. Various drift
attractors in spiral wave controlled by square-shaped contour-line feedback are
also investigated. A brief explanation is presented.
