Investigation of Handle Surfaces and Grasping Tasks

Research Trainee: Curtis Irwin, PhD Student, Biomedical Engineering, University of Wisconsin at Madison

Faculty Researcher: Robert G. Radwin, PhD, Professor of Industrial and Systems Engineering and Biomedical Engineering at the University of Wisconsin at Madison

A new dynamometer was designed to investigate the effecs of handle shape and size on sub-maximal grip force in order to understand how to design handles that maximize grip force and minimize effort. This is particularly important for designing industrial hand tools and equipment to reduce the risk of musculoskeletal disorders. The new dynamometer will quantify the effects of different handle geometries on the resultant force vector generated during gripping. This is done by obtaining both force magnitude and direction in two orthogonal axes during a single squeeze. This device will also permit users to change the shape and size of different handles in width and breadth. A biomechanical model will estimate finger tension for each condition. The results will enable us to determine the handle dimensions resulting in the greatest force and the least stress in the hands.

Twelve subjects (6 males and 6 females) performed simple load transfer and twisting tasks using bare aluminum handles or ones covered with a high-friction material. The tasks were one under dry and oil-saturated conditions at three different load levels (weight). Grip force was measured via strain gauges mounted in the handles. Analysis of various showed that all three independent variables were significant (p < .001).

 

Publications resulting from this project:
Irwin CB, Radwin RG. A new method for estimating hand internal loads from external force measurements. Ergonomics. 2008;51(2):156-167. doi:10.1080/00140130701526408.

 

Research trainee’s current position:
Curtis Irwin completed his PhD in 2007 and is currently a Human Factors Engineer at Design Concepts.