Investigating the Performance of Soft Robotic Adaptive Feet with Longitudinal and Transverse Arches

Biped robots usually adopt feet with a rigid structure that simplifies walking on flat grounds and yet hinders ground adaptation in unstructured environments, thus jeopardizing stability. We recently explored in the SoftFoot the idea of adapting a robotic foot to ground irregularities along the sagittal plane. Building on the previous results, we propose in this paper a novel robotic foot able to adapt both in the sagittal and frontal planes, similarly to the human foot. It features five parallel modules with intrinsic longitudinal adaptability that can be combined in many possible designs through optional rigid or elastic connections. By following a methodological design approach, we narrow down the design space to five candidate foot designs and implement them on a modular system. Prototypes are tested experimentally via controlled application of force, through a robotic arm, onto a sensorized plate endowed with different obstacles. Their performance is compared, using also a rigid foot and the previous SoftFoot as a baseline. Analysis of footprint stability shows that the introduction of the transverse arch, by elastically connecting the five parallel modules, is advantageous for obstacle negotiation, especially when obstacles are located under the forefoot. In addition to biped robots' locomotion, this finding might also benefit lower-limb prostheses design.Comment: Submitted to Frontiers in Robotics and A

A bioinspired humanoid foot mechanism

© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This paper introduces an innovative robotic foot design inspired by the functionality and the anatomy of the human foot. Most humanoid robots are characterized by flat, rigid feet with limited mobility, which cannot emulate the physical behavior of the foot-ground interaction. The proposed foot mechanism consists of three main bodies, to represent the heel, plant, and toes, connected by compliant joints for improved balancing and impact absorption. The functional requirements were extracted from medical literature, and were acquired through a motion capture system, and the proposed design was validated with a numerical simulation

Toward an adaptive foot for natural walking

Many walking robot presented in literature stand on rigid flat feet, with a few notable exceptions that embed flexibility in their feet to optimize the energetic cost of walking. This paper proposes a novel adaptive robot foot design, whose main goal is to ease the task of standing and walking on uneven terrains. After explaining the rationale behind our design approach, we present the design of the SoftFoot, a foot able to comply with uneven terrains and to absorb shocks thanks to its intrinsic adaptivity, while still being able to rigidly support the stance, maintaining a rather extended contact surface, and effectively enlarging the equivalent support polygon. The paper introduces the robot design and prototype and presents preliminary validation and comparison versus a rigid flat foot with comparable footprint and sole