Application of pressure mapping techniques to measure push and gripping forces with precision

Abstract

Gripping and push forces, also named coupling forces, have induced effects on the transmission of the vibration in the upper limb. The assessment of the vibration exposure with powered tools thus requires that these man/machine coupling parameters are controlled and monitored. To date, no reliable metrological systems enable their precise measurements. This study first investigated how much precision could be expected from the pressure mapping technique for the determination of coupling forces by means of numerical integration. Then a specific procedure was worked out and validated to instrument hand-held tools and measure the coupling forces with regard to the appropriate current standards. The proposed method was applied as a case study on an ordinary breaker and an anti-vibration breaker.

Radial force distribution changes associated with tangential force production in cylindrical grasping, and the importance of anatomical registration

“…The present findings of distally focussed forces agrees with many previous studies on maximal grasp (Gurram, R. et al, 1993; Shimojo, M. et al, 1995; Wimer, B. et al, 2009; Hall, C., 1997; Lemerle, P. et al, 2007; Sinsel, E. W. et al, 2010). That distal force concentration is consistent for sub-maximal and maximal tasks suggests that the distal phalanges are likely the most important effector for F r production.…”

“…Similarly, F r distribution has been characterized using discrete sensors dispersed around the cylinder (Wimer, B. et al, 2009) or using finer pressure sensor arrays (Aldien, Y. et al, 2005; Lemerle, P. et al, 2007; Seo, N. J. et al, 2007; Young, J. G. et al, 2010), but in these studies the F r data were described with respect to the handle rather than with respect to the hand. This may be problematic in cases of non-negligible inter-subject hand size variation, where positions on the handle cannot be mapped directly to hand structures.…”

Pressure sensor matrix for indirect measurement of grip and push forces exerted on a handle

“…A possible reason for this is the impossibility to detect the contribution of friction forces to the coupling forces by means of pressure sensor matrices. This hypothesis is also supported by the findings reported in [23]; the presence of friction forces was in fact recognised as a contribution to the coupling forces. The amount of such a deviation is not known and is operator dependent.…”

“…The proposal to use matrices of polymeric pressure sensors, which can be wrapped around a handle has been studied for some years for different reasons and there is a great amount of literature concerning hand-arm vibration measurement [12,[16][17][18][19][20][21][22][23]. However, to our knowledge, there is no published analysis about the algorithms used for indirect measurement and the uncertainty involved.…”

“…Within the EU project VIBTOOL [17,18], since 2003, research has been conducted on the measurement of grip and push forces through spatial integration of contact pressure distributions at the hand-handle interface and a number of papers were published [13,14,[19][20][21][22][23]. These activities were conducted in close interaction with standardization bodies and led in 2007 to the publication of the standard ISO 15230:2007 [15] which incorporated the methods to indirectly measure grip and push forces described in its Annex B.…”