Method for quantitative determination of the pressure comfort of a seat cushion
First Claim
1. A method for determining pressure comfort of a cushion, the method comprising the steps of:
- mechanically loading at least one of a seat cushion or a backrest surface of a seat to be tested in accordance with a normal occupation by a seated person;
during this loading, determining the pressure distribution on a seat cushion surface or the backrest surface using a measuring mat placed in between, said measuring mat containing a plurality of pressure sensors arranged and distributed according to a pattern, each of said pressure sensors having separate measurement signal leads;
combining signals from individual ones of said pressure sensors in the measuring mat groupwise in accordance with anthropomorphically determined areas with different pressure sensitivity thresholds, and evaluating the signals from the individual pressure sensors separately for each area, with said seat cushion surface being divided into the following areas with respective pressure sensitivity thresholds (p0) given in mbar;
(a) two symmetrically located thigh areas with p0 =40;
(b) two symmetrically located cheek areas with p0 =40;
(c) two symmetrically located ischial hump areas with p0 =60; and
(d) a centrally located coccyx area with p0 =50;
wherein said backrest surface is divided into the following areas with corresponding pressure sensitivity thresholds (p0) given in mbar;
(a) a centrally located pelvic area with p0 =30;
(b) a centrally located lordotic area with p0 =30;
(c) two symmetrically located lateral bead areas with p0 =40; and
(d) two symmetrically located shoulder areas with po =30;
within each area, evaluating local pressure values of the pressure distribution corresponding to the difference of a local pressure from the respective pressure sensitivity threshold (po) via multiplication by a quality factor so as to form an evaluated seat pressure distribution as a product function with the respective pressure sensitivity threshold (po) being assigned a value of 1 as the quality factor and, starting with the respective pressure sensitivity threshold (p0), with an increasing difference of a local sitting pressure from the pressure sensitivity threshold (p0) a progressively increasing value is used as the quality factor;
integrating the pressure distributions evaluated in this manner in the individual areas, and adding up the integral values of all the areas;
outputting a sum of the adding step as a rating number for the pressure comfort of the seat cushion or the seat back cushion of the seat.
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Abstract
A method is provided for quantitative determination of the pressure comfort of a seat cushion. For this purpose, the sitting surface of the seat cushion to be tested is loaded mechanically in a manner that corresponds to a normal individual sitting in it, and the seat distribution is then determined with an interposed measuring mat. The signals from the individual pressure sensors of the measuring mat are summarized in accordance with anthropomorphically determined loading ranges with different pressure sensitivity thresholds groupwise and evaluated separately for the individual areas. For this purpose, the pressure measurement signals are multiplied by a factor or a pressure-dependent progressively increasing evaluation function and the product function is integrated. The pressure sensitivity threshold is assigned a value of 1. Depending on the difference between the respective pressure measurement value and the pressure sensitivity threshold (p0) the quality factor increases approximately parabolically or in geometric stages with increasing difference. The sum of the integral values obtained for the product functions is output as a rating number for the pressure comfort of the cushion. The comfort investigation can be performed with subjects of different sizes or seat testing punches of different sizes (5%, 50%, and 95% percentile), with an average or total value for all the results being used as a rating number for pressure comfort.
13 Citations
13 Claims
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1. A method for determining pressure comfort of a cushion, the method comprising the steps of:
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mechanically loading at least one of a seat cushion or a backrest surface of a seat to be tested in accordance with a normal occupation by a seated person; during this loading, determining the pressure distribution on a seat cushion surface or the backrest surface using a measuring mat placed in between, said measuring mat containing a plurality of pressure sensors arranged and distributed according to a pattern, each of said pressure sensors having separate measurement signal leads; combining signals from individual ones of said pressure sensors in the measuring mat groupwise in accordance with anthropomorphically determined areas with different pressure sensitivity thresholds, and evaluating the signals from the individual pressure sensors separately for each area, with said seat cushion surface being divided into the following areas with respective pressure sensitivity thresholds (p0) given in mbar; (a) two symmetrically located thigh areas with p0 =40; (b) two symmetrically located cheek areas with p0 =40; (c) two symmetrically located ischial hump areas with p0 =60; and (d) a centrally located coccyx area with p0 =50; wherein said backrest surface is divided into the following areas with corresponding pressure sensitivity thresholds (p0) given in mbar; (a) a centrally located pelvic area with p0 =30; (b) a centrally located lordotic area with p0 =30; (c) two symmetrically located lateral bead areas with p0 =40; and (d) two symmetrically located shoulder areas with po =30; within each area, evaluating local pressure values of the pressure distribution corresponding to the difference of a local pressure from the respective pressure sensitivity threshold (po) via multiplication by a quality factor so as to form an evaluated seat pressure distribution as a product function with the respective pressure sensitivity threshold (po) being assigned a value of 1 as the quality factor and, starting with the respective pressure sensitivity threshold (p0), with an increasing difference of a local sitting pressure from the pressure sensitivity threshold (p0) a progressively increasing value is used as the quality factor; integrating the pressure distributions evaluated in this manner in the individual areas, and adding up the integral values of all the areas; outputting a sum of the adding step as a rating number for the pressure comfort of the seat cushion or the seat back cushion of the seat. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for determining a user pressure comfort of a cushion, the method comprising the steps of:
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loading the cushion in accordance with a normal use due to a user; determining a pressure distribution on the cushion using a measuring mat, said measuring mat containing a plurality of pressure sensors providing pressure signals arranged and distributed according to a coverage area; groupwise combining the pressure signals from groupings of said pressure sensors in the measuring mat according to anthropomorphically determined areas of the user having different pressure sensitivity thresholds; separately evaluating for each of said anthropomorphically determined areas the signals of the pressure sensors combined groupwise; within each of said anthropomorphically determined areas, local pressure values of the pressure distribution which correspond to a difference of a local pressure from a respective pressure sensitivity threshold (po) are evaluated via multiplication with a quality factor to form an evaluated pressure distribution as a product function, said pressure sensitivity threshold (p0) being assigned an initial quality factor value which progressively increases with increasing differences between the local pressure values from the respective pressure sensitivity threshold (p0); integrating the pressure distributions evaluated above for each of said anthropomorphically determined areas; adding-up the integrated values of all of said anthropomorphically determined areas; and using the sum of said adding step as a rating number for the pressure comfort of the cushion.
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Specification