Linear Modeling of Human Hand-Arm Dynamics Relevant to Right-Angle Torque Tool Interaction

Ay, Haluk; Sommerich, Carolyn M.; Luscher, Anthony F.

doi:10.1177/0018720813485977

Cited by 7 publications

(6 citation statements)

References 36 publications

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“…The polynomial fit for the handle force between the rig and human testing data sets provides higher accuracy than that for the displacement measurements. Further investigation determined that the handle force is affected largely by target torque and tool size (Ay, 2011). On the other hand, handle displacement is sensitive to those factors and to operator dynamics and joint rate (Ay, 2011).…”

Section: Discussionmentioning

confidence: 99%

“…Task-related variables include target torque, joint rate (also referred as joint hardness or stiffness and defined as the amount of fastener rotation during torque build-up), tool orientation and fastener location (height, reach distance) relative to the tool operator (Johnson et al , 2008; Lin and McGorry, 2009; Lin et al , 2006; Oh and Radwin, 1997, 1998; Sommerich et al , 2009). Tool operator hand–arm dynamics have been shown to be dependent upon several factors, including the operator’s work posture, gender (strength), musculoskeletal health and work experience with torque tools (Ay et al , 2013; Lin et al , 2001, 2003c, 2007; Sesto et al , 2006). Tool operator response has been quantified in terms of tool handle displacement, grip force, subjective ratings (discomfort, acceptability) and physiological effects (muscle activity, edema, human–arm mechanical properties) (Chourasia et al , 2009; Kihlberg et al , 1995; Lin and McGorry, 2009; Lin et al , 2006, 2003b).…”

Section: Introductionmentioning

confidence: 99%

“…Modeling has provided important insights regarding hand–arm dynamics. Measurement and modeling of human hand–arm dynamics has been the objective of several previously published articles from the fields of biomechanics (Dong et al , 2009; Flash and Gurevich, 1991; Flash and Mussa-Ivaldi, 1990; Ketteringham et al , 2008; Reynolds and Soedel, 1972; Soechting and Flanders, 1997), ergonomics (Ay et al , 2013; 2010a; Joshi et al , 2008; Lin et al , 2001, 2003c, 2003b) and haptics research (Mailah et al , 2009; Springer and Ferrier, 2002). These models were validated based on an input–output relationship between torque and displacement or vice versa.…”

Section: Introductionmentioning

confidence: 99%

“…A static hand–arm model was considered applicable in the vicinity of arm equilibrium position for small displacement inputs in the range of 1-2 cm (Flash and Gurevich, 1991; Flash and Mussa-Ivaldi, 1990). However, Lin et al (2001, Lin et al , 2003c) and Ay et al (Ay et al , 2013, 2010b) experimentally validated second-order linear dynamic hand–arm models for tasks such as torque tool operation, that result in greater displacements due to impulsive forces. These models described the human hand–arm response to torque tool operation in terms of effective stiffness, mass and damping parameters.…”

Section: Introductionmentioning

confidence: 99%

“…The study participants experienced various joint rates and working postures. The previously validated assessment methodology (Ay et al , 2013) was used to determine the effective stiffness, mass and damping parameters of the study participants. A database of parameters for both men and women working in a variety of positions (e.g.…”

Section: Introductionmentioning

confidence: 99%

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A dynamic simulator for the ergonomics evaluation of powered torque tools for human assembly

Luscher

Sommerich

2017

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Purpose The purpose of this study is to design and develop a testing device to simulate interaction between human hand–arm dynamics, right-angle (RA) computer-controlled power torque tools and joint-tightening task-related variables. Design/methodology/approach The testing rig can simulate a variety of tools, tasks and operator conditions. The device includes custom data-acquisition electronics and graphical user interface-based software. The simulation of the human hand–arm dynamics is based on the rig’s four-bar mechanism-based design and mechanical components that provide adjustable stiffness (via pneumatic cylinder) and mass (via plates) and non-adjustable damping. The stiffness and mass values used are based on an experimentally validated hand–arm model that includes a database of model parameters. This database is with respect to gender and working posture, corresponding to experienced tool operators from a prior study. Findings The rig measures tool handle force and displacement responses simultaneously. Peak force and displacement coefficients of determination (R2) between rig estimations and human testing measurements were 0.98 and 0.85, respectively, for the same set of tools, tasks and operator conditions. The rig also provides predicted tool operator acceptability ratings, using a data set from a prior study of discomfort in experienced operators during torque tool use. Research limitations/implications Deviations from linearity may influence handle force and displacement measurements. Stiction (Coulomb friction) in the overall rig, as well as in the air cylinder piston, is neglected. The rig’s mechanical damping is not adjustable, despite the fact that human hand–arm damping varies with respect to gender and working posture. Deviations from these assumptions may affect the correlation of the handle force and displacement measurements with those of human testing for the same tool, task and operator conditions. Practical implications This test rig will allow the rapid assessment of the ergonomic performance of DC torque tools, saving considerable time in lineside applications and reducing the risk of worker injury. DC torque tools are an extremely effective way of increasing production rate and improving torque accuracy. Being a complex dynamic system, however, the performance of DC torque tools varies in each application. Changes in worker mass, damping and stiffness, as well as joint stiffness and tool program, make each application unique. This test rig models all of these factors and allows quick assessment. Social implications The use of this tool test rig will help to identify and understand risk factors that contribute to musculoskeletal disorders (MSDs) associated with the use of torque tools. Tool operators are subjected to large impulsive handle reaction forces, as joint torque builds up while tightening a fastener. Repeated exposure to such forces is associated with muscle soreness, fatigue and physical stress which are also risk factors for upper extremity injuries (MSDs; e.g. tendinosis, myofascial pain). Eccentric exercise exertions are known to cause damage to muscle tissue in untrained individuals and affect subsequent performance. Originality/value The rig provides a novel means for quantitative, repeatable dynamic evaluation of RA powered torque tools and objective selection of tightening programs. Compared to current static tool assessment methods, dynamic testing provides a more realistic tool assessment relative to the tool operator’s experience. This may lead to improvements in tool or controller design and reduction in associated musculoskeletal discomfort in operators.

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Section: Discussionmentioning

confidence: 99%