STUDY OF PRECISION POSITIONING BY FRICTION DRIVE (3RD REPORT) - IN-PROCESS-ASSIGNED VELOCITY CONTROL

The friction drive mechanism has the advantages of simple structure an d ability to move tables quickly and quietly. The previous report desc ribed the method that obtains a short settling time, but it was necess ary to know the traction characteristic, moving mass and guide-way fri ction resistance, thus making it impractical. The present report descr ibes 1) higher positioning accuracy obtained by replacing the DC servo motor and linear measuring device, described in the previous report, w ith a direct drive (DD) motor and laser measuring system; 2) a newly d eveloped Point-to-Point (PTP) velocity control for in-process-assigned table movement when the traction and other characteristics are unknow n; 3) mechanical improvements and a velocity control that give the sam e sub-micron positioning accuracy and settling time as the experiment described in our previous report; and 4) a simulation using a kinemati c equation to better understand the mechanical system's movements.