Environment-adaptive track mechanism with continuously transformable grousers

This study presents EATbot, an environment-adaptive tracked robot featuring an arc-grouser mechanism that continuously modulates grouser protrusion and the resulting ground-contact profile rather than altering the overall track posture. Conventional fixed-profile tracks must compromise grouser geometry because low-profile treads improve flat-ground smoothness, whereas highly protruded grousers improve rough-terrain and stair-edge engagement. To address this fixed-grouser-profile trade-off, the proposed mechanism continuously modulates the protrusion of arc-shaped grousers over the range from a retracted low-profile configuration to a maximum-protrusion high-engagement configuration within a single track module. A kinematic model and virtual-work-based torque formulation were developed to characterize grouser protrusion behavior and load-dependent actuation requirements. The arc-grouser geometry was designed to maximize usable protrusion within chain discretization, internal interference, packaging, and actuator constraints, while a non-collinear structural offset was incorporated to prevent simultaneous dead-center locking during continuous transformation. Stair-climbing tests verified the predicted climbable domain and demonstrated successful ascent up to a maximum equivalent inclination of [Formula: see text]. Driving stability experiments showed that the retracted configuration decreased RMS vibration by 5.1% on flat terrain, whereas the maximum-protrusion configuration reduced vibration by 87.9% on rough terrain. Payload transformation tests up to 40 kg further demonstrated practical high-load operation. These results indicate that continuous grouser-profile transformation can mitigate the fixed-profile trade-off between flat-ground smoothness and stair/rough-terrain engagement while preserving the continuous-contact characteristics of tracked locomotion.