Impedance Control Self-Calibration of a Collaborative Robot Using Kinematic Coupling

Abstract

This paper presents a closed-loop calibration approach using impedance control. The process is managed by a data communication architecture based on open-source tools and designed for adaptability. The calibration procedure uses precision spheres and a kinematic coupling standard machine tool components, which are suitable for harsh industrial environments. As such, the required equipment is low cost (approximately $2000 USD), robust, and is quick to set up, especially when compared to traditional calibration devices. As demonstrated through an experimental study and validated with a laser tracker, the absolute accuracy of the KUKA LBR iiwa robot was improved to a maximum error of 0.990 mm, representing a 58.4% improvement when compared to the nominal model. Further testing showed that a traditional calibration using a laser tracker only improved the maximum error by 58 µm over the impedance control approach.

Keywords

• calibration
• data processing
• force control
• impedance control
• industrial communication
• manufacturing, process, and service automation
• optimization
• physical human–robot interaction
• redundant robots
• robot control