C-TRAC: Terrain-Adaptive Control for Articulated Tracked Robots via Contact-Aware Reinforcement Learning

Abstract

Articulated tracked robots face significant challenges in maintaining stable locomotion over uneven terrain due to unknown contact points between tracks and ground, which are critical for dynamic control. Unlike legged robots, where contact locations can be predicted, tracked systems require real-time adaptation to varying terrains. This paper presents C-TRAC, a terrain-adaptive control framework that integrates reinforcement learning with a contact-modeling variational autoencoder (C-VAE) to enable robust obstacle traversal. We first train a C-VAE in simulation to reconstruct high-fidelity contact information (position and binary probability) from noisy sensor measurements. This model learns a latent representation of terrain contacts, capturing complex interactions between the robot’s kinematics and environment. Subsequently, we employ an asymmetric Soft Actor-Critic (SAC) algorithm to optimize a control policy that leverages the predicted contact data for adaptive track control during locomotion. Extensive experiments validate C-TRAC in both simulated and real-world scenarios. In benchmark tests against state-of-the-art (SOTA) methods using RoboCup Rescue Robot League environments, our approach achieves superior obstacle traversal speed (up to 66.67% faster on 45<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">◦</sup> staircase) and stability (up to 47.53% more stable on the oblique terrace) compared to contact-agnostic RL baselines and model-based methods. Notably, zero-shot sim-to-real transfer demonstrates consistent performance in unstructured outdoor ruins, also confirming the framework’s practicality.