Design and development of functional foot for agile and dynamic legged robots

Recent advances in high-power density actuators, numerical algorithms, and machine learning techniques enable legged robots to move dynamically and agilely on the ground. However, the robots are still significantly restricted to accessing extreme terrains, such as steep hills and vertical walls, because of their lack of foot holding capability. In order to increase the traction capacity of the foot, appropriate adhesion mechanisms need to be applied to the foot. So far, existing adhesion mechanisms as the foot component have difficulties meeting the conditions of attaching/detaching on surfaces during a short stepping period to support relatively heavy robots with limited power. This thesis provides two functional foot designs that work on porous surfaces and ferromagnetic surfaces to tackle these challenges in two approaches. Specifically, this work first introduces the foot design that utilizes two different foot pads (a rubber pad and micro-spine arrays), which can be switched based on the slip condition to compensate for their drawbacks. A passive slip detection mechanism as well as a lock & release mechanism have been designed to switch the rubber pad to the micro-spine arrays in the event of a slip. In addition, this thesis presents a novel adhesion mechanism: an electropermanent magnet with the Halbach magnet array (H-EPM). The H-EPM improves the force reduction at an air gap of the typical electropermanent magnet. Using the H-EPM and a magnetorheological elastomer, the magnetic foot design has been introduced. We provide an analytical adhesion force model of the magnetic foot using a magnetic circuit and characterize the H-EPM operation to generalize the design. Overall, the traction capacities of the two foot designs have been demonstrated via experimentation. Finally, this thesis shows new extreme locomotion of dynamic legged robots equipped with the functional feet that the robots jump to and land on a 50° inclined block, walk on an inverted steel wall, and climb a vertical steel wall at a speed of 0.91 BL/s.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• Park, Jaejun

Contributors dc:contributor

• Park, Hae-Won
• Hsiao-Wecksler, Elizabeth
• Krishnan, Girish
• Kim, Joohyung
• Ramos, Joao

• Foot design
• Quadruped robot
• Adhesion mechanism
• Micro-spine array
• Electropermanent magnet
• Halbach array
• Climbing robot

Statement dc:rights

• © 2022 Jaejun Park

Language dc:language

eng

Handle dc:identifier

https://hdl.handle.net/2142/115744

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/115744