AttnWalk: Attention-Enhanced Reinforcement Learning With Reward-Predicted Curriculum for Wheel-Legged Robots

Ao Zhang
,
Liang Ding
,
Zhelin Zhang
,
Peng Xu
,
Ruyi Zhou
Lei Ye
Lei Ye
,
Haibo Gao
,
Zongquan Deng
AttnWalk: a real hexapod wheel-legged robot traversing snowy steps, the attention controller, and obstacle interaction experiments. Composed from Figs. 1, 2 and 8 of the AttnWalk paper (Zhang et al., IEEE TIE, 2026). Original research images and method diagram.
Abstract
AttnWalk learns adaptive locomotion for a hexapod wheel-legged robot using proprioception alone. A multi-head attention module identifies informative states in recent sensor history and modulates leg and wheel actions as terrain changes. A reward-prediction curriculum adjusts task sampling over velocity commands and terrain difficulty to support progressively harder training. Simulation and outdoor hardware experiments evaluate terrain traversal and wheel-leg mode adaptation. The real robot reaches 2.5 m/s on flat ground and continuously climbs 13 cm steps in the reported tests.
Type
Publication
IEEE Transactions on Industrial Electronics, 2026 (Early Access)

Learning terrain changes from contact and motion

Without a terrain camera or elevation map at deployment, the controller must infer changing terrain from its own motion and contact history. AttnWalk attends to informative historical states and adjusts wheel and leg commands, favoring rolling on flat ground and stepping when higher obstacles are encountered.

Attention and curriculum

The policy uses the current observation as a query over recent proprioceptive history. Its attention and action-modulation weights provide a view of which past events influence wheel-leg coordination. A reward-prediction curriculum jointly samples velocity commands and terrain difficulty, reducing training on infeasible combinations while retaining learnable challenges.

The paper evaluates the approach in simulation and on a real hexapod wheel-legged robot, including snow, grass, steps, paved surfaces, and cobblestones. Reported hardware results include 2.5 m/s flat-ground speed and continuous traversal of 13 cm steps. These results concern the tested platform and settings; the method uses proprioceptive feedback rather than explicit look-ahead terrain perception.

Publication status: IEEE TIE Early Access, 2026. Accepted on 17 July 2026.

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