Homing and establishing reference frames for motion axes in radiation systems
AssigneeVarian Medical Systems, Inc.
InventorRobert T. Wiggers
Life of this patent
Estimating the term…
Abstract
A method of homing motion axes in a radiation system uses a motor and one or more hardstops. A load is driven by a motor to move toward a hardstop during which an electrical parameter of the motor is monitored. A reference position for the motion axis is defined when the monitored electrical parameter reaches or exceeds a determined value. Alternative to monitoring the motor electrical parameter, the motor velocity may be monitored during the motion and a reference position for the motion axis is defined when the monitored motor velocity falls to or below a determined value. Alternatively, the load velocity may be monitored during the motion and a reference position for the motion axis is defined when the monitored load velocity falls to or below a determined value.
Claims9
A method of homing a motion axis including a motor, a load, and one or more feedback devices coupled to at least one of the motor and the load in a radiation system having at least two hardstops defining a range of travel of the motion axis, comprising:
- providing a value of distance or angle between a first hardstop and a second hardstop;
- moving the motion axis toward the first hardstop and contacting the motion axis with the first hardstop to perform a first homing routine, whereby a first reference position of the motion axis is established;
- moving the motion axis toward the second hardstop and contacting the motion axis with the second hardstop to perform a second homing routine, whereby a second reference position of the motion axis is established;
- calculating a value of distance or angle between the established first and the second reference positions;
- comparing the calculated value of distance or angle between the established first and the second reference positions with the provided value of distance or angle between the first hardstop and the second hardstop;
- and
- accepting the first and second reference positions for the motion axis if the calculated value and the provided value agree.
Dependencies are inferred from the claim text.