Adaptive compliant milling control for switch rail edge deburring within an FDAFC-based robotic framework

Abstract. The burrs remaining on switch rails are prone to cracking or even fracturing during operation, thereby diminishing their service life. Moreover, the complex profile of the switch rail makes stable robotic milling difficult, with constantly changing posture and milling force. Therefore, this paper proposes a feed–displacement dual-channel adaptive force control (FDAFC) framework comprising a tangential force–speed loop and a normal-force–displacement loop. The tangential loop employs feed-per-tooth normalization combined with an engagement-aware force–speed mapping and first-order gain scheduling. This design adaptively corrects the feed to regulate tangential force and compensate for engagement-dependent nonlinearities, thereby reducing cross-coupling with the normal channel. The normal loop uses position-based impedance control with radial basis function (RBF)-scheduled inertia, damping, and stiffness to track the desired normal force under time-varying loads. A Lyapunov-guided adaptation law guarantees uniform boundedness, asymptotic tracking-error convergence, and closed-loop stability. Finally, integrated co-simulation and experiments substantiate the efficacy of the compliant milling force-tracking controller for switch rail deburring. The long-distance milling method for robots proposed in this study offers a new approach for automatic burr removal from the switch rail.