The effect of friction in transmission components on the dynamics of legged robots

The enduring stability of industrial manipulators, even when powered off, can be attributed to the joint friction, which prevents these systems from succumbing to their own weight. Although the friction-based mechanism provides effective stiff position control, specifically in pick-and-place applications, its suitability in legged robots is less ideal due to the necessity for rapid regulation of compliant interactions with environmental factors. There is, however, a dearth of metrics to measure a robot’s performance degradation due to mechanical losses in actuators and transmissions. This paper aims to bridge this gap by introducing a fundamental formulation that leverages the mechanical efficiency of transmissions to assess the impact of power losses in mechanical transmissions on the comprehensive dynamics of a robotic system. This paper presents quantitative evidence substantiating the intuitive fact that robots’ apparent inertia escalates with joint friction. Additionally, it illustrates that robots utilizing high gear ratio and low efficiency transmissions can statically bear more significant external loads. The provided framework, we hope, will serve as a key toolkit for designing future generations of legged robots capable of effectively interacting with their environment.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2023

Author dc:creator

• Sim, Youngwoo

Contributors dc:contributor

• Ramos, Joao

• Actuation System Design
• Robotic System Design
• Humanoid Design

Statement dc:rights

• Copyright 2023 Youngwoo Sim

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/122087

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F122087