Rotating Gantry


An innovative large area XY gantry where THETA angle can exceed 20-deg allows large relative motions of the independent X1 and X2 parallel axes. This method allows users to control orthogonality in XY plane or intentionally introduce large THETA rotation of the Y axis about the X1 and X2 axes, but also rotates the Y axis around a virtual programmable point.


The system contains two pivot points on X1 and X2 axes to allow Y cross-axis to rotate around each of X-axis and be displaced linearly about each of them.


Though the current system manufactured with motorized ball screw actuators with brushless servo motor/encoders, given approach also readily lends itself to system design with direct drive linear servo motors.


This gantry design covers more working area than robots using delta kinematics, which are also more expensive and bulky.


Optional Z-axis can be also easily installed.


The dual axes gantry controller can independently control both X1 and X2 axes positions and theta (X1-X2).


The ability of independent X1 and X2 axes control, allow them to be displaced any programmable distances, which in turn, allows Y axis rotation around any programmable pivot point.


The system described in this article was designed for the XY travel 800 x 800 mm travel, with 20 degrees Y axis rotation. Theta angle control achieved resolution 1 arc-sec with repeatability 3 arc-sec.  Design can be extended to larger XY travels and THETA adjustment if required.


Gantry was successfully installed in the semiconductor wafer, reticle alignment, and  flat panel display manufacturing applications.

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