Robot-Arm Screw Coupling for Vibration-Robust Force Sensing

The patent introduces a restoring element (spring) as an intermediary between the robot arm and the tool. This spring element mechanically couples the two components while its deformation serves as an indirect measure of actuation force. The spring absorbs high-frequency vibrations and impacts, filtering out disturbance variables that would otherwise corrupt direct strain gauge measurements. This intermediary mechanism transforms the measurement problem from directly measuring force in a noisy environment to measuring spring deformation, which is inherently filtered.

The patent replaces complex mechanical force measurement systems (strain gauges, load cells) with a simpler optical or electromagnetic distance measurement system. Instead of directly measuring force through mechanical sensors susceptible to vibrations, the system uses a distance measuring element (such as an optical sensor or capacitive sensor) to measure the position of the restoring element. This substitution leverages non-contact or minimal-contact sensing technologies that are inherently more robust to mechanical disturbances, thereby improving measurement robustness while adding minimal complexity.

The patent divides the transmission system into segmented components: a first transmission element connected to the robot arm, a restoring element, and a second transmission element connected to the tool. The guide constrains only the relative movement between these segmented elements in the actuation direction, while allowing independent movement of each segment. This segmentation allows the guide to focus on constraining only the necessary degrees of freedom (movement in the actuation direction) while leaving other movements unrestricted, thereby achieving movement precision without excessive complexity.