Body-State Supervisory Modulation with Dynamic Support Trajectory for Hexapod Robot Locomotion on Deformable Terrain

Abstract

The paper presents proposed Body-State Supervisory Modulation (BSSM) framework integrated with a Dynamic Support Trajectory (DST) to improve hexapod locomotion stability on deformable terrain. Traditional adaptive locomotion techniques, such Environment-Trailed Trajectory (ETT), use force- or trajectory-based activation to control corrective support motion, which can become unreliable in situations involving penetration, sinkage, and delayed contact. The proposed structure retains the original support trajectory formulation while replacing supervisory logic driven by body height, roll, and pitch for trajectory-dependent activation. This allows for physically consistent corrective actions without explicit terrain estimation. The framework was assessed on deformable terrain using a Hexaquad robot with compliant ground contact in MATLAB Simscape Multibody. The suggested approach produced smoother posture regulation and better locomotion stability by reducing the RMS error of roll, pitch, and body height by ${2 8. 5 5 \%}$, ${1 7. 1 6 \%}$, and ${1 3. 7 9 \%}$, respectively, as compared to ETT. The findings demonstrate that on soft or uneven ground, the system maintains more reliable contact with the surface, controls its posture more fluidly, and achieves greater overall movement stability.