Lateral position detection for friction stir systems

A friction stir method for processing at least a first workpiece, wherein a system for said method comprises a spindle actuator coupled to a rotary tool comprising a rotating member for contacting and processing said first workpiece, comprising:

• measuring at least one force signal or a parameter related to said force experienced by said rotary tool during said processing, and
• estimating a lateral alignment of said rotating member relative to a selected lateral position or a selected path.

A friction stir method for processing at least a first workpiece using a friction stir weld system comprising a spindle actuator coupled to a rotary tool comprising a rotating member for performing said processing, the method comprising:

• measuring a force experienced by said rotary tool or a parameter related to said force experienced by said rotary tool during said processing, said force based on a plurality of force sensor signals associated with said measured force or said measured parameter at a plurality of locations on said first workpiece, and
• comparing said plurality of force sensor signals to discern a direction towards a feature of said workpiece from a current location of said rotating member, and
• determining at least one lateral alignment offset value for said rotating member based at least on said discerned direction to decrease a lateral distance of said rotary tool relative to said selected lateral position, said selected path, or said direction.