Human beings have a touch and force estimation mechanism beneath their feet. They use this feeling of touch and force to maintain balance, walk, run and perform various agile motions. This paper presents a new sensor platform beneath the humanoid feet, enabled by a pragmatic model based compliant foot design and sensor configuration that mimics the human tactile sensory system for contact force measurement in humanoid robots. Unlike previous force sensor based approaches, the system is defined as a total and sufficient method of Ground Reaction Force (GRF) and Zero Moment Point (ZMP) measurement for balancing and walking using contact force feedback in mid to full sized humanoids. The conventional systems for the GRF and ZMP measurement are made of heavy metallic parts that tend to be bulky and vulnerable to inertial noises upon high acceleration. In addition to low cost and reliable operation, the proposed system can withstand shock and enable agile motion much like humans do with their footpad. The proposed foot is manufactured using state-of-the-art technique with elastomer padding which not only protects the sensors but also acts as a compliance beneath the foot giving integrity in structural design. This composite layer provides compliance and traction for foot collision while the contact surfaces are sampled for pressure distribution which can be mapped into three axis force and ZMP. A single step training process is required to relate the sensor readings to force measurement.
The system’s capability of contact force measurement, subsequent ZMP estimation is experimentally verified with the application of appropriate software. Moreover, a simulation study has been conducted via Finite Element Analysis (FEA) of the footpad structure to analyze the proposed footpad structure. The experimental results demonstrate why this can be a major step toward a biomimetic, affordable yet robust contact force and ZMP measurement method for humanoid robots.
This work was supported by the Office of Naval Research, Grant N00014-15-1-2128 as part of development of Project SAFFiR (Shipboard Autonomous Firefighting Robot). / Master of Science / How we interact with the surfaces in contact with us has a crucial role for balancing and walking with agility. The biological touch and force measurement systems in human is currently unmatched, not even mimicked in a significant way in the state-of-the-art humanoid robots’ systems. Human beings use this feeling of touch and force beneath the feet to maintain balance, walk, run and perform various agile motions. This research aims to find a holistic system in humanoid robot’s feet design that can mimic this human characteristics of force estimation beneath the feet and using that estimation for balancing and walking. A practical model based sensor configuration is derived from the rigorous study of human and humanoid robot’s feet contact with the ground. The sensors are tactile in nature, and unlike previous below feet based approaches, the system is defined as a total and sufficient system of Ground Reaction Force (GRF) and Center of Pressure (CoP) measurement. The conventional systems for this purpose are not only highly expensive but also having error in quantification during accelerated movement. The proposed foot is designed following the practical model derived and manufactured using the state-of-the-art mechanism for having a soft cushion between the sensors and the contact surfaces. In addition to low cost and reliable operation, the proposed system can withstand shock and enable agile motion much like humans do with their footpad. The quantification of the forces and pressure from the sensor readings and developed using appropriate software and algorithms.
The system’s capability of contact force measurement, subsequent Center of Pressure measurement is experimentally verified with the application of appropriate software. Moreover, a simulation study has been conducted of the footpad structure to analyze the proposed footpad structure. The experimental results demonstrate why this can be a major step toward a biomimetic, affordable yet robust contact force and Center of Pressure measurement method for human-like robots.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/87082 |
| Date | 12 December 2018 |
| Creators | Sifat, Ashrarul Haq |
| Contributors | Electrical and Computer Engineering, Abbott, A. Lynn, Furukawa, Tomonari, Williams, Ryan K. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | Creative Commons Attribution-ShareAlike 3.0 United States, http://creativecommons.org/licenses/by-nc-sa/3.0/us/ |
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