Virtual product design and assessment has become a valuable tool in the development and evaluation of new buildings (and consumer products) as well as the interior design of automobiles. While these processes are beginning to work well for whole body designs targeted at accommodating population anthropometries, particularly in an effort to reduce injuries associated with awkward postures (Corlett et al. 1980, Chang et al. 2003, Chaffin 2005, Perez 2005), they have not been applied to hand tool or device design. It has been shown that repeated use of hand tools by individuals with hand dimensions significantly different than for which the tool was intended has resulted in an increased potential for hand-related injuries (Cobb et al. 1996, Meagher 1987, Kar et al. 2007, Markison 2007), particularly when significant force is required to operate the tool (Sancho-Bru et al. 2003, Molteni et al. 2008). Virtual hand models have been ineffective in addressing such anthropometric tool-fit issues. Current technological impediments related to available virtual hand models include (1) a lack of a solid geometry hand with accurate surface representation and accurate joint kinematics defined by centers of rotation, (2) a limited capacity in accounting for anthropometric scaling (e.g. the relationships between individual finger segment dimensions) (3) missing information on predicting how the hand grips objects and the forces applied during gripping, and (4) an inability to account for tissue compliance (particularly at the finger tips and palmar surface). The proposed project intends to address these impediments by developing a 3D geometric hand model, to be integrated into the current CAD design software products used by design engineers (e.g., SolidWorks, ProE) to evaluate the interaction between the hand and a new product. The proposed Phase 1 research will result in a virtual hand model that specifically targets the first two impediments (listed above) and will establish a draft framework (to be used to scope future research) for the necessary parameterization to address (3) and (4). At the conclusion of phase 1, a stand-alone software program with a scalable geometric hand representation with kinematically realistic articulating digits will be produced. The virtual hand model will be developed using the open-source SimTK core libraries (Sherman et al. 2005, Delp et al. 2007, Schmidt et al. 2008). The bones and joints of the hand will be modeled using rigid body structures to mathematically replicate laboratory recorded hand anthropometry, joint centers, and kinematics. The surface representation of the hand will be modeled using a similar method used by rigid body spring models (RBSM) (Kawai 1980). An integrated hand model, incorporating both the proposed surface-deformation/skeletal model and existing muscle models, would provide a powerful analysis tool for 1) understanding hand related injury mechanisms associated with grip posture and force and 2) optimizing tool design in-silico, prior to workplace deployment.
Public Health Relevance: There currently exist no methods for design engineers to assess prospective design changes in a virtual environment as related to the overall tool-hand fit with respect to different population hand sizes. This has led to hand tool designs that are inappropriate for a large number of users and whose repetitive use will result in an increased potential for injury (Meagher 1987, Markison 2007). The overall goal of this project is to develop a scalable, virtual hand model that can be used to evaluate and determine appropriate hand-tool coupling interfaces, information that can be used to design hand tools to accommodate the hand sizes and hand shapes of end users.
Public Health Relevance Statement: There currently exist no methods for design engineers to assess prospective design changes in a virtual environment as related to the overall tool-hand fit with respect to different population hand sizes. This has led to hand tool designs that are inappropriate for a large number of users and whose repetitive use will result in an increased potential for injury (Meagher 1987, Markison 2007). The overall goal of this project is to develop a scalable, virtual hand model that can be used to evaluate and determine appropriate hand-tool coupling interfaces, information that can be used to design hand tools to accommodate the hand sizes and hand shapes of end users
