Method and system for finding a tool center point for a robot using an external camera

A vision-based robot calibration system for calibrating a tool-frame for a tool attached to a robot using a camera comprising:

• said robot, said robot having a wrist that is moveable, said robot having a control system that moves said robot and said wrist into different poses, said tool attached to said robot being at different orientations for said different poses, said robot control system defining a wrist-frame for said wrist of said robot such that said robot control system knows a position and an orientation of said wrist for said different poses via a kinematic model of said robot;
• said camera, said camera being mounted external of said robot, said camera capturing an image of said tool;
• a wrist pose sub-system that designates a point on said tool in said image of said tool as an image tool center point of said tool and moves said robot into a plurality of wrist poses, said image tool center point being a point on said tool that is desired to be an origin of said tool-frame for said kinematic model of said robot, each wrist pose of said plurality of wrist poses being constrained such that said image tool center point of said tool is located within a specified geometric constraint in said image captured by said camera;
• a tool center point calculation sub-system that calculates a tool-frame tool center point relative to said wrist-frame of said wrist of said robot for said tool as a function of said specified geometric constraint and also as a function of said position and said orientation of said wrist of said robot for each wrist pose of said plurality of wrist poses;
• a robot kinematic incorporation subsystem that defines said tool-frame of said tool relative to said wrist-frame for said kinematic model of said robot as said tool-frame tool center point.

A vision-based robot calibration system for calibrating a tool-frame for a tool attached to a robot using a camera comprising:

• means for providing said robot, said robot having a wrist that is moveable, said robot having a control system that moves said robot and said wrist into different poses, said robot control system defining a wrist-frame for said wrist of said robot such that said robot control system knows a position and an orientation of said wrist for said different poses via a kinematic model of said robot;
• means for providing said camera, said camera being mounted external of said robot, said camera capturing an image of said tool;
• means for designating a point on said tool in said image of said tool as an image tool center point of said tool;
• means for moving said robot into a plurality of wrist poses, each wrist pose of said plurality of wrist poses being constrained such that said image tool center point of said tool is located within a specified geometric constraint in said image captured by said camera;
• means for calculating a tool-frame tool center point relative to said wrist-frame of said wrist of said robot for said tool as a function of said specified geometric constraint and also as a function of said position and said orientation of said wrist of said robot for each wrist pose of said plurality of wrist poses;
• means for defining said tool-frame of said tool relative to said wrist-frame for said kinematic model of said robot as said tool-frame tool center point;
• and,
• means for operating said robot to perform desired tasks with said tool using said kinematic model of said robot with said defined tool-frame.

A computerized method for calculating a tool-frame tool center point relative to a wrist-frame of a robot for a tool attached at a wrist of said robot using a camera comprising:

• providing a computer system for running computer software, said computer system having at least one computer readable storage medium for storing data and computer software;
• mounting said camera external of said robot;
• operating said camera to capture an image of said tool;
• defining a point on a geometry of said tool as a tool center point of said tool;
• defining a constraint region on said image captured by said camera;
• moving said robot into a plurality of wrist poses, each wrist pose of said plurality of wrist poses having a known position and orientation within a kinematic model of said robot;
• each wrist pose of said plurality of wrist poses having a different position and orientation from other wrist poses of said plurality of wrist poses;
• analyzing said image captured by said camera with said computer software to locate said tool center point of said tool in said image for each wrist pose of said plurality of wrist poses;
• correcting said position and orientation of each wrist pose of said plurality of wrist poses using said camera such that said tool center point of said tool located in said image captured by said camera is constrained within said constraint region defined for said image;
• calculating a tool-frame tool center point relative to said wrist-frame of said robot with said computer software as a function of said position and orientation of each wrist pose of said plurality of wrist poses as corrected to constrain said tool center point in said image to said constraint region on said image;
• updating said kinematic model of said robot with said computer software to incorporate said tool-frame tool center point relative to said wrist-frame of said robot as an origin of said tool-frame of said tool within said kinematic model of said robot;
• and,
• operating said robot using said kinematic model as updated to incorporate said tool-frame tool center point to perform desired tasks with said tool.

A computerized calibration system for calculating a tool-frame tool center point relative to a wrist-frame of a robot for a tool attached at a wrist of said robot using an externally mounted camera comprising:

• a computer system that runs computer software, said computer system having at least one computer readable storage medium for storing data and computer software;
• operating said camera to capture an image of said tool;
• a constraint definition sub-system that defines a point on a geometry of said tool as a tool center point of said tool and defines a constraint region on said image captured by said camera;
• a wrist pose sub-system that moves said robot into a plurality of wrist poses, each wrist pose of said plurality of wrist poses having a known position and orientation within a kinematic model of said robot;
• each wrist pose of said plurality of wrist poses having a different position and orientation from other wrist poses of said plurality of wrist poses;
• an image analysis sub-system that analyzes said image captured by said camera with said computer software to locate said tool center point of said tool in said image for each wrist pose of said plurality of wrist poses;
• a wrist pose correction sub-system that corrects said position and orientation of each wrist pose of said plurality of wrist poses using said camera such that said tool center point of said tool located in said image captured by said camera is constrained within said constraint region defined for said image;
• a tool-frame tool center point calculation sub-system that calculates a tool-frame tool center point relative to said wrist-frame of said robot with said computer software as a function of said position and orientation of each wrist pose of said plurality of wrist poses as corrected to constrain said tool center point in said image to said constraint region on said image;
• and,
• a kinematic model update sub-system that updates said kinematic model of said robot with said computer software to incorporate said tool-frame tool center point relative to said wrist-frame of said robot as an origin of said tool-frame of said tool within said kinematic model of said robot.

A robot calibration system that finds a tool-frame tool center point relative to a wrist-frame of a tool attached to a robot using an externally mounted camera comprising a computer system programmed to:

• analyze an image captured by said externally mounted camera to locate a point on said tool in said image designated as an image tool center point of said tool for each wrist pose of a plurality of wrist poses of said robot, each wrist pose of said plurality of wrist poses being constrained such that said image tool center point is constrained within a geometric constraint region on said image, each wrist pose of said plurality of wrist poses having a known position and orientation within a kinematic model of said robot, each wrist pose of said plurality of wrist poses having a different position and orientation within said kinematic model of said robot from other wrist poses of said plurality of wrist poses;
• calculate said tool-frame tool center point relative to said wrist-frame of said robot as a function of said position and orientation of each wrist pose of said plurality of wrist poses;
• update said kinematic model of said robot to incorporate said tool-frame tool center point relative to said wrist-frame of said robot as an origin of said tool-frame of said tool within said kinematic model of said robot;
• and,
• deliver said updated kinematic model of said robot to said robot such that said robot operates using said updated kinematic model to perform desired tasks with said tool attached to said robot.