Prosthetic Arm Force Reducer Team 1 – Halliday's ... - Ohio University

6.0 Concept Selection
6.1 Data and Calculations for Feasibility and Effectiveness Analysis
6.1.1 - Static Analysis of Split-Hook Gripping Force and Necessary User Input
Two of our proposed designs resemble traditional prosthetic terminal devices. Two of the most
important parameters of a gripping device are the gripping force it provides, and the force needed
to open it. The following analyses are configured to resemble a classic “split hook” design.
Figure 6.1.1 – Classic Split Hook Design
This design uses two hooks, one is mobile (upper hook in picture), and one is fixed (lower hook).
The hooks are held together by a series of rubber bands. The user opens the hook by applying a
force to the cable (seen at the right side of the picture). The amount of rubber bands, and the
nature of the “cable post” are two things that can alter the gripping force, and the amount of user
input needed to open the mobile hook. The following analyses utilize simple static models to
formulaically simulate this design.
UDetermining Gripping ForceU:
Figure 6.1.2 shows a simple static model of the moveable hook on a split hook prosthetic
terminal device.
Fr = Spring or rubber band force Fg = Gripping force
Dr = Rubber Band Distance from Pivot L = Overall length of hook
Figure 6.1.2 – Static Model of Moveable Hook
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