EP0505922

A graphics plotter for drawing a series of connected vector lines forming a plot. The plotter has a motor control for controlling motors which drive a pen to move relative to a medium at a variable velocity in a plane defined by a major axis and a minor axis perpendicular to the major axis. The motor control determines a minimal nonzero terminal velocity of the pen along the major axis at a point at which a maximum change in direction occurs. The motor control has a program for determining a minimal nonzero optimal velocity at the point of maximum change in direction. The minimal nonzero optimal velocity is the junction of a ramped-down optimal velocity preceding the point of maximum change in direction and a ramped-up optimal velocity succeeding the point of maximum change in direction. The motor control also includes a double integrating filter implemented in the sampled domain for limiting the acceleration of the pen along the major axis at the point of maximum change in direction to a discrete value such that the difference between the actual pen trajectory and a desired pen trajectory is an amount less than or equal to a predetermined acceptable error.