Design and Development of a Reconfigurable Testing System for Biomechanical and Orthopedic Experimental Research

Abstract

The goal of this work was to develop a versatile mechanical testing load frame and control system that incorporates hardware and software components that can be readily reconfigured to meet the unique needs of a wide variety of orthopedic testing applications. The technical requirements of the system included a maximum axial loading capacity of at least 2000lbf and a maximum torsional loading capacity of at least 250 in-lbf. The system was physically designed using Solidworks, including the load frame and selected actuators, before being fabricated and assembled. Custom software for the system was developed using LabVIEW, and consists of three primary sections: the control system loop, data recording, and the user interface. The control system loop is structured as a finite state machine (FSM) to allow for easier troubleshooting as well as expansion of control types. The data recording consist of two separate loops, one of which operates deterministically to store data in a clustered real time first in first out (RTFIFO) variable while the second records this collected data to a text file on the cRIO system. The user interface allows the operator to change the system control type such as position or load, create a file for data recording, and displays information about the system during operation. The user interface also includes various safety checks to prevent the user from damaging the system. The system’s final cost came out to approximately $47,023 including a safety screen, custom fixturing for upcoming Biomechanical Environments Laboratories (BMEL) projects, and an estimation for work hours. The system is being prepared for used in an Food and Drug Administration (FDA) Good Laboratory Practice (GLP) regulated study and will be validated as required for the study. A user’s manual was created for the system including information concerning assembly for a linear and torsional loading scenario, operation of the current software version, and steps for adding and changing sensors in the system.