<p>Impedance control (IC) is a widely adopted strategy for manipulator interaction tasks, as it balances contact compliance and manipulation accuracy through impedance parameters. However, IC methods with fixed impedance parameters face significant limitations in handling complex interaction scenarios, particularly when both contact compliance and manipulation accuracy are critical. For instance, in lower-limb exoskeleton robots, the controller must guarantee contact compliance to avoid user discomfort, while simultaneously maintaining sufficient accuracy to preserve proper limb posture. This dual requirement presents significant challenges for fixed-parameter IC approaches. To address this issue, this paper introduces a novel impedance model using a barrier function (BF) mechanism. The proposed model leverages a BF to strictly regulate tracking accuracy within a predefined range while ensuring contact compliance. Building on this model, a variable impedance controller with stability guarantees is designed. Comparative experiments and simulations demonstrate that the proposed method significantly outperforms fixed-parameter IC methods, achieving superior contact compliance and markedly improved tracking performance in interaction tasks.</p>