A milling test-based coordinate calibration approach for the dual-robot mirror milling system with a measurement module

Accurate collaborative positioning by dual robots is crucial for achieving high precision in dual-robot mirror milling operations. However, the tool frames constructed in conventional dual-robot coordinate calibration approaches need to be substituted by a new set designated for the mirror milling, which may induce a notable reduction of collaborative positioning accuracy. This paper presents a novel collaborative coordinate calibration technique designed explicitly for the dual-robot mirror milling system with a measurement module, avoiding the need for subsequent tool frame replacement for mirror milling. The proposed method starts from designing a multi-probe ultrasonic measurement module on the mirror milling system's supporting head and developing an online workpiece pose identification technique by using the ultrasonic measurement. A specially designed mirror milling test is then implemented to correlate the dual-robot collaborative pose information with the pose daviation observed between the machined and ideal design features. By identifying the machined feature's pose, we realize a high-precision dual-robot coordinate calibration approach that ideally suites for the dual-robot mirror milling system equipped with a measurement module. The effectiveness and advantage of proposed method has been validated through a set of comparative experiments. Experiment results show that the proposed method obviously outperforms the benchmarking dual-robot coordinate calibration method reliant on laser tracker technology.