Method of controlling robot movement

A method of controlling movement of a tool that is supported by a robot having a wrist that is moveable about three wrist axes that are each associated with a wrist origin, comprising the steps of:

• (A) moving the wrist origin along a predetermined wrist path;
• (B) determining a desired tool position;
• (C) determining a next tool position from a range of tool positions available by moving only the wrist about the wrist axes with the wrist origin in a current wrist origin position;
• (D) determining a position vector between the current wrist origin position and the next tool position;
• (E) determining a set of wrist axis positions necessary to move the tool into the next tool position from the determined position vector and the determined next tool position;
• (F) moving the tool from a current tool position into the next tool position by moving only the wrist into the determined set of wrist axis positions.

A system for controlling robot movement, comprising:

• a robot arm having a plurality of arm axes about which said arm is moveable;
• a robot wrist supported on one end of said arm and having a wrist origin and a plurality of wrist axes that provide movement of said wrist relative to said wrist origin;
• a tool supported by said wrist;
• a wrist actuator for moving said wrist about said wrist axes;
• and
• a controller including
• means for determining a desired tool position;
• means for determining a next tool position from a range of tool positions available by moving only the wrist about the wrist axes with the wrist origin in a current wrist origin position;
• means for determining a position vector between the current wrist origin position and the next tool position;
• means for determining a set of wrist axis positions necessary to move the tool into the next tool position from the determined position vector and the determined next tool position;
• and
• command means for commanding said wrist actuator to move the tool from a current tool position into the next tool position by moving only the wrist into the determined set of wrist axis positions.

A method of controlling movement of a tool that is supported by a robot having a wrist that is moveable about a plurality of wrist axes that are associated with a wrist origin, comprising the steps of:

• (A) positioning the tool adjacent a preselected tool path;
• (B) moving the wrist origin along a predetermined wrist path corresponding to the preselected tool path;
• (C) moving the tool in a first direction away from the preselected tool path by moving only the wrist about at least one of the wrist axes by determining a desired tool position that is spaced from the preselected path, determining a range of available tool positions based upon only moving the wrist about the wrist axes, determining a next tool position, from within the range of available tool positions, that corresponds to the desired tool position, and moving the tool to the next tool position by moving only the wrist while maintaining the wrist origin on the wrist path;
• (D) moving the tool in a second direction back toward the preselected tool path by moving only the wrist about at least one of the wrist axes;
• and
• (E) cyclically performing steps (C) and (D) while performing step (B).