| 摘要 |
A dual drive control system applicable to precision machine tools and robotics eliminates the consequences resulting from coulomb friction and stiction by avoiding the operating points where these defects manifest themselves. A first embodiment consists of a dovetail slide having a base and a motive slide, two motors, a feedscrew, and a helical gear assembly. The feedscrew is mounted parallel to the linear motive direction of the slide; a helical gear is mounted with its axis normal to the feedscrew and with its teeth meshing with the screw threads of the feedscrew. The first motor is mounted on the base and imparts rotation to the feedscrew. The second motor is mounted on the slide and imparts rotation to the helical gear. In operation, the first motor turns the feedscrew at a continuous speed. The second motor drives the helical gear so that its teeth follow the threads of the rotating feedscrew. When the speeds are eequal there is zero linear motion of the helical gear assembly relative to the feedscrew, and consequently zero motion of the dovetail slide. However, changing the differential speed of the motors produces a linear motion of the slide that is proportional to the differential motor speed. Because the individual motor do not reverse direction, and thereby passes through zero velocity, there is no resulting jitter due to coulomb friction or stiction.
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