Robot Tool Contact Detection Using Dual Lag-Error Thresholds

The patent replaces force and torque sensors (mechanical measurement systems) with an analysis of drive arrangement operating parameters (position, speed, acceleration lag errors). By monitoring deviations in these operational parameters and comparing them against threshold values, the system detects tool contact without requiring additional force sensing hardware, thus substituting a mechanical sensor system with a control-system-based detection method.

The patent introduces threshold values as an intermediary element that mediates between the raw drive parameters and the contact detection decision. The evaluation unit uses these thresholds to interpret lag error signals, converting continuous parameter deviations into discrete contact/non-contact states. This intermediary threshold mechanism enables reliable contact detection without direct force measurement.

The patent segments the contact detection process into two distinct stages using two different threshold values: a first threshold for initial contact indication and a second (higher) threshold for confirmation. This segmentation allows the system to quickly respond to potential contact events while requiring verification before final contact confirmation, thereby reducing false detections caused by noise or transient disturbances.

The first threshold serves as a preliminary detection mechanism that triggers further evaluation when exceeded. Rather than immediately confirming contact at the first threshold crossing, the system uses this preliminary indication to initiate a verification process through the second threshold, enabling fast initial response while maintaining reliability through staged validation.