Design and Experimental Evaluation of a Flexible Wheel‐Foot Actuator in Beach Terrain for Amphibious Robots

ABSTRACT The efficacy of field exploration robots is contingent upon their capacity and proficiency in traversing unstructured and complex terrains. In the context of beach terrain, substantial variations in the mechanical properties of the substrate can be triggered by fluctuations in moisture levels within granular materials. This poses a substantial challenge to the effectiveness of actuators designed for amphibious crawling, which depend exclusively on plowing force after penetration or surface friction to adapt to such environments. In this study, we propose a cost‐effective, adaptable wheel‐foot actuator that is designed based on the mechanical properties of granular media. The configuration consists of a circular wheel as the primary structural element and a regular arrangement of flexible feet, which collectively provide a combined traction force of penetration and friction. A total of 3840 experiments were conducted under controlled conditions on both the flexible wheel‐foot scheme and the grousered wheel scheme. The outcomes of these experiments enabled us to ascertain and validate the penetration difficulty tendency of wet granules with varying moisture contents. Secondly, a comparison of the transportation cost, normalized antislip coefficient, standard deviation of vertical displacement, energy consumption, and other parameters of 40 schemes under the same working conditions allowed us to determine the structural parameters, such as the number and stiffness of flexible feet. This comparison also demonstrated that the proposed scheme has significant advantages in suppressing slip and reducing energy consumption. In field tests conducted in an amphibious environment, the proposed scheme demonstrated a statistically significant reduction in slip rate (10.4%) and energy consumption (22.8%) compared to other tested schemes. Subsequent evaluations were conducted through tests of water‐land transition capability, extrication ability, and the ability to navigate through harsh ground conditions. These evaluations confirmed the effectiveness of the proposed scheme.