Force-Control for the Automated Footwear Testing System

Lewis, Greg (2005) Force-Control for the Automated Footwear Testing System. Canadian Industrial Problem Solving Workshops > 9th IPSW [Calgary 15/5/2005- 19/52005].

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Abstract/Summary

The Automated Footwear Testing System (AFTS) is a robotic system designed to replicated the movement and loading of a shoe as it contacts the ground during common human movements. By doing so, the AFTS can serve as a system for the functional testing of different footwear designs in a manner that is difficult to achieve by standard testing systems. The AFTS consists of four main components: a robotic Stewart platform, a rigid fixed frame, a load cell and a prosthetic foot. Motion of the foot relative to the ground is created by rigidly fixing the foot to the frame and moving the platform relative to the foot. The Stewart platform has six degrees of kinematic freedom and can reproduce the required complex three-dimensional motion path within the limitations of its range of motion. While the platform is in contact with the footwear, the six-axis load cell measures the three-dimensional forces and moments acting on the prosthetic foot.

For the AFTS, a movement path is specified, translated into platform coordinates and executed on the machine. During the execution, the load cell measures the forces and moments that act on the prosthetic foot. We wish to find the particular movement path of the Stewart platform that will generate the target force profile. Thus, we are interested in solving an inverse problem. The main goal of the workshop was to investigate potential solution methods for this ‘force-control’ problem, including looking into its feasibility.

Item Type:	Study Group Report
Study Group:	Canadian Industrial Problem Solving Workshops > 9th IPSW [Calgary 15/5/2005- 19/52005]
Company Name:	Biomechanigg Research Incorporation
Industrial Sector:	Transport and Automotive None/Other Medical and pharmaceutical
Additional Contributors:	Westbrook, Rex and Cole, Gerald K. and Artoun, Ojenie and Griffin, Kent and Lim, Jisun and Liu, Xiao Ping and Odegaard, James and Williams, Sarah
ID Code:	193
Deposited By:	Michele Taroni
Deposited On:	03 November 2008

Problem Statement

The Automated Footwear Testing System (AFTS) is a robotic system designed to replicated the movement and loading of a shoe as it contacts the ground during common human movements. The force profiles and movement paths for specific types of movements can be acquired experimentally, but it is found that when the same shoe used by the human subject is mounted on the prosthetic foot of the AFTS, and the experimentally measured movement path is replicated, the forces and moments measured to be acting on the prosthetic foot do not match the experimental data. It is hoped that an accurate model of the mechanics of the AFTS will help explain these discrepancies.

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