A CLOSED-LOOP FEEDBACK-CONTROLLED SOLENOID FOR PRECISION MOTION

摘要

This is a solenoid-based pen raising apparatus for raising and lowering a pen of a pen plotter. There is a pen holder (18) for holding a pen (52) mounted for vertical up and down motion in combination with a pen held thereby and a solenoid (18) having a coil (22) and an armature (28) disposed in the armature for powered longitudinal movement in a first direction. A first linkage (54) connects the armature to the pen holder for raising and lowering the pen holder in combination with longitudinal movement of the armature. A second linkage connects a spring (30) to apply a force urging the armature in a second direction opposite the first direction. A motion sensor (32) senses the linear position of the pen holder and outputs a positional signal reflecting the linear position. A driver circuit (24) outputs a variable current to the coil of the solenoid as a function of a control signal at an input thereof. Finally, there is control logic (26) for inputting the positional signal and a desired position request and for outputting control signals to the driver circuit to move the pen holder to the desired position.