Adversarial training (AT) is one of the most effective defenses against
adversarial attacks for deep learning models. In this work, we advocate
incorporating the hypersphere embedding (HE) mechanism into the AT procedure by
regularizing the features onto compact manifolds, which constitutes a
lightweight yet effective module to blend in the strength of representation
learning. Our extensive analyses reveal that AT and HE are well coupled to
benefit the robustness of the adversarially trained models from several
aspects. We validate the effectiveness and adaptability of HE by embedding it
into the popular AT frameworks including PGD-AT, ALP, and TRADES, as well as
the FreeAT and FastAT strategies. In the experiments, we evaluate our methods
under a wide range of adversarial attacks on the CIFAR-10 and ImageNet
datasets, which verifies that integrating HE can consistently enhance the model
robustness for each AT framework with little extra computation.