Error‑Compensated Dual‑Robot Coordinated Milling of Circular Parts Via Orthogonal‑Axis Decomposition

Industrial robots are attractive for circular and cylindrical machining operations, but limited stiffness and posture-dependent accuracy restrict achievable diameter and tolerances. This paper proposes an error-compensated coordinated strategy for a dual hexapod system that differs from existing single- and dual-robot approaches by decomposing the circular toolpath into orthogonal linear motions for each robot and by using ISO 230-4 ballbar measurements to drive direct path compensation, without relying on a proprietary coordinated-motion package. Ballbar tests in three planes and at radii of 50, 100, 150, and 300 mm, show that the coordinated strategy roughly doubles the usable circular radius relative to the 150 mm single-robot reference, corresponding to about a fourfold increase in circular machining area. Machining experiments on an aluminum cylinder part indicate that compensated dual-robot roundness errors fall in the 34–55 μm range, with circular deviation below 100 μm and part dimension variation within ± 0.30–0.35 mm, compared with ± 0.15–0.20 mm for the single robot. The method brings the dual-robot system into a mid-precision regime approximately compatible with IT7–IT8 tolerance grades; dimensional control remains slightly inferior to CNC, but the approach offers a flexible, scalable route to workspace-extended circular machining.