Axis controller for robotic actuator
AssigneeAnorad Corporation
InventorsAnwar Chitayat, Robert C. Goldstein, Mustansir A. Faizullabhoy
Life of this patent
Estimating the term…
Abstract
A control for a robotic actuator employs a position processor to determine the phase of a pair of electrooptically generated position signals as well as to keep track of the number of whole cycles of the position signals. Whole cycles are tracked using a prediction technique depending upon the continuity of position and velocity. A command processor employing the sensed position produces a velocity signal for driving the robotic actuator. When very slow motion is sensed, the response of the controller is appropriately reduced to maintain a velocity command signal generally in proportion to the motion.
Claims18
A position processor for a robotic controller of the type employing first and second sensed position signals having a phase relationship, said phase relationship containing information about a position of an object within a cycle of position, said object being movable over a plurality of cycles of position, comprising:
- means for comparing phases of said first and second sensed position signals to produce a reported position within a cycle of position;
- means for producing a predicted position of said object including full cycles of position and a position within a cycle of position;
- means for differencing said predicted position within a cycle of position and said reported position to produce a position error signal;
- and
- means responsive to said position error signal for accumulating a smoothed position signal representing said position of said object.
A command processor for a robotic controller of the type employing a sequence of measurements of position of an object, said measurements being spaced apart a predetermined time, comprising:
- means for differencing a measurement of position and a preceding measurement of position to produce a measured velocity signal;
- means for producing a velocity command signal;
- means for differencing said measured velocity signal and said velocity command signal to produce a velocity error signal, said velocity error signal being usable for driving said object;
- means for counting a number of consecutive ones of said predetermined times during which said measured velocity signal is zero;
- and
- means for slowing change of said measured velocity signal in dependence on said number.
A command processor for a robotic controller of the type employing a sequence of measurements of position of an object, said measurements being spaced apart a predetermined time, comprising:
- means for differencing a measurement of position and a preceding measurement of position to produce a measured velocity signal;
- means for producing a velocity command signal;
- means for differencing said measured velocity signal and said velocity command signal to produce a velocity error signal, said velocity error signal being usable for driving said object;
- and
- a velocity bias compensator effective to sense and store a non-zero value of said measured velocity signal at a time when said velocity command signal should be zero and to subsequently compensate said velocity command signal with the stored value to compensate for velocity bias.
A home position processor for a robotic controller of the type employing a home position signal for sensing a home position of an object, comprising:
- means for moving said object through a search range containing said home position;
- means for storing an extreme value of said home position signal;
- means for comparing a new value of said home position signal with a previously stored extreme value and for replacing said previously stored extreme value with said new value if said new value exceeds said previously stored extreme value;
- and
- means for storing a number associated with a position of each new value which is stored, a number stored at the completion of said search range being associated with the most extreme value of said home position signal and representing said home position.
A method of determining a home position in a robotic controller of the type employing a home position signal for sensing a home position of an object, compris- ing:
- moving said object through a search range containing said home position;
- storing an extreme value of said home position signal;
- comparing a new value of said home position signal with a previously stored extreme value and replacing said previously stored extreme value with said new value if said new value exceeds said previously stored extreme value;
- and
- storing a number associated with a position of each new value which is stored, a number stored at the completion of said search range being associated with the most extreme value of said home position signal and representing said home position.
A robotic controller for controlling a position of an object, comprising:
- means for producing first and second position signals related to said position, said first and second position signals having a phase relationship containing information about said position;
- means responsive to said phase relationship and effective to produce a reported position signal within a cycle of said first and second position signals;
- means for producing a prediction of said reported position signal;
- means for differencing said reported position signal and said prediction to produce a position error signal;
- said means for producing a prediction being responsive to said position error signal for updating said prediction;
- means responsive to said error signal for accumulating a smoothed position signal;
- means for differencing a value of said smoothed position signal with a previous value of said smoothed position signal to produce a tach signal;
- means for slowing changes in said tach signal in response to at least two successive values of said smoothed position signal being the same to produce a corrected tach signal;
- means for producing a velocity command signal;
- means for differencing said velocity command signal and said corrected tach signal to produce a velocity error signal;
- and
- means responsive to said velocity error signal for driving said object.
Dependencies are inferred from the claim text.