Adaptive Compliance Control for Homomorphic Parallel-Legged Hexapod Robot in Unstructured Environments

To improve the environmental adaptability of parallel-legged walking robots, this study proposes compliant control strategies for a hexapod robot with dual parallel-leg mechanisms. First, a posture controller was designed to suppress attitude disturbances caused by unknown terrain heights (30 mm and 50 mm obstacles), maintaining platform tilt within 0.5°. Second, an adaptive impedance control method was introduced to accommodate varying ground stiffness (ranging from 2×10⁴ N/m to 2×10⁵ N/m), reducing foot penetration depth by 46.7% compared to conventional control. Finally, the STM32 microprocessor was selected as the core, and multiple sensors were installed on the robot to build the adaptive compliant system. These methods were validated on a custom heterogeneous terrain, including a rigid 50 mm obstacle and a soft 30 mm obstacle. The compliant control system achieved precise position compensation matching obstacle profiles and ensured stable locomotion over unstructured surfaces, demonstrating its effectiveness for real-world rough terrain traversal.