Faculty Advisor or Committee Member

Gregory S. Fischer, Advisor

Faculty Advisor or Committee Member

Gregory S. Fischer, Committee Member

Faculty Advisor or Committee Member

William R. Michalson, Committee Member

Faculty Advisor or Committee Member

Mahdi Agheli, Committee Member

Identifier

etd-3886

Abstract

The focus of this paper is on the development of a modular AFO (Ankle Foot Orthosis) subsystem for the greater L.A.R.R.E (Legged Anthropomorphic Robotic Rehab Exoskeleton) Exoskeleton. The main role of the AFO device is in the role of medical rehabilitation, by providing passively-powered dorsiexion support to the user's ankle in order to prevent foot drop. It is able to accomplish this role through the use of a torsional spring attached to the ankle joint. Additionally, the AFO must also be able to provide sensory-feedback to the greater L.A.R.R.E system in order to help control walking gait. It can detect the orientation of the ankle through the use of both a potentiometer and IMU attached at the ankle joint, and it can detect which part of the foot is in contact with the ground through a specially-designed tactile sensor embedded within the sole of the AFO. This sensor consists of Force-Sensing Resistor sensors encased within a polyurethane rubber mold to provide protection from wear and tear as well as provide a rough surface to keep the device from slipping. The development of this "Sole-Sensor" was fairly extensive, with multiple iterations of the sensor being developed over the course of the project. It was found that Sole-Sensor works best when the resin geometry is shaped in such a way that it concentrates all forces applied on it directly above the FSRs. The development of a working Sole-Sensor subsystem allowed a proper test of the Right-foot AFO system within a VICON Motion-Capture room to test Foot-position detection and Center-of-Pressure point tracking. Translating the AFO CoP point into the VICON Lab's "World Frame" and comparing it to the independently calculated Force-Plate CoP point shows a maximum position displacement of +/- 3cm along the AFO's X-axis and +/- 5cm along the Y-axis.

Publisher

Worcester Polytechnic Institute

Degree Name

PhD

Department

Robotics Engineering

Project Type

Dissertation

Date Accepted

2020-05-15

Accessibility

Unrestricted

Subjects

Ankle Foot

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