Method for the quantitative determination of the dynamic seating comfort of a seat padding

• US 20050091817A1
• Filed: 08/21/2002
• Published: 05/05/2005
• Est. Priority Date: 10/02/2001
• Status: Abandoned Application

• Current Assignee: Daimler Chrysler Company LLC (Stellantis NV)
• Original Assignee: Daimler Chrysler Company LLC (Stellantis NV)
• Inventors: Eger, Michael, Pfahler, Karl, Renner, Lothar, Kassing, Lothar
• Application Number:
  US10/491,489
• Publication Number:
  US 20050091817A1
• Time in Patent Office: Days
• US Class Current: 29/407.07
• CPC Class Codes: A47C 31/126 for chairs
• CPC Class Codes: G01M 99/001 Testing of furniture, e.g. seats or mattresses
• CPC Class Codes: Y10T 29/49764 with testing or indicating
• CPC Class Codes: Y10T 29/49774 by vibratory or oscillatory movement

Abstract

A method for determining an evaluation number which is representative of the quality of the dynamic sitting comfort of upholstered seat elements of a vehicle seat. A flexible measuring mat is applied to the upholstered seat element in a defined position and a matrix, which covers the surface, of force measuring sensors which operate without hysteresis is integrated into said measuring mat. A test person or a test body which behaves anthropomorphically in terms of oscillation is positioned on the vehicle seat. In order to carry out a measurement, this body/seat system is excited so as to oscillate, for example by traveling over a bad stretch of road. The signals supplied by the force measuring sensors are added with the same phase to form a composite signal. The frequency response of the body/seat system is determined from this composite signal.

Claims

1-11. -11. (canceled)

12. A method for determining an evaluation number which is representative of a quality of the dynamic sitting comfort of upholstered elements of a vehicle seat, said method comprising the steps:

applying a flexible measuring mat to the upholstered seat element of the vehicle seat in a defined position, said measuring mat being provided with a plurality of separate force measuring sensors which are integrated into the measuring mat, are distributed in the manner of a grid so as to cover a surface of the mat, are also each inherently flexible, are each operate virtually without hysteresis up to a frequency of approximately 25 Hz and are each provided with signal terminals which lead outwards to an evaluation device;

subsequently loading the vehicle seat with a seat loading body under conditions close to reality;

positioning said seat loading body in a defined position, centrally on the vehicle seat, wherein said seat loading body is one of a natural test person and a freely movable test body which is designed so as to be anthropomorphic with respect to the oscillatory behavior of the vehicle seat;

exciting a system formed by the seat and the body so as to oscillate at least within a frequency range of 0 to 30 Hz;

at least one of recording and analyzing signals which are present at signal terminals of the force measuring sensors during the excitation where the signals of all the force measuring sensors are added at least approximately with the same phase to form a composite signal;

determining the spectral distribution of the amplitudes of a response oscillation of the body/seat system from the time profile of said composite signal; and

determining a ratio of an area integral of said frequency response up to a specific limit frequency;

using a limit value of said ratio of the area integral being used at the limit frequency as said evaluation number of the dynamic sitting comfort of the upholstered element of the vehicle seat.

13. The method as claimed in claim 12, wherein the freely movable test body is of an anthropomorphic design and comprises a thigh and posterior area covered with upholstery a back area connected at the hip joint in an articulated fashion and is covered with upholstery, and a pair of lower leg simulators connected to the thigh simulators in the knee joint area (20) in an articulated fashion and supported on the floor by means of footplates which are connected in an articulated fashion, wherein hard parts of the thigh and posterior area and the back area simulating as true to nature as possible, at least on the underside and the bearing side, the shape of the pelvic bone and of the thighs including the thigh joints of a human skeleton, and wherein the coverage of the hard parts with upholstery simulating as true to nature as possible the natural soft parts in the posterior area and back area in accordance with the layer thickness, softness, elasticity and damping behavior as well as local distribution of these parameters in the area of the two sitting pressure points, wherein the freely movable test body which is of anthropomorphic design is also provided with passive ballast in the form of a plurality of ballast weights which are at least one of inserted on the inside into the thigh and posterior area and secured to the inside of the back area in order to obtain the necessary sitting weight.

14. The method as claimed in claim 12, wherein the body/seat system is excited by means of stochastic oscillations, and the spectral distribution is determined from the composite signal of the response oscillation by means of a Fourier frequency transformation.

15. The method as claimed in claim 14, wherein the vehicle seat to be evaluated with respect to its dynamic sitting comfort is installed according to predetermined regulations in the vehicle, and wherein the body/seat system is excited stochastically to oscillate by the wheels of the vehicle.

16. The method as claimed in claim 15, wherein the stochastic excitation of oscillations takes place as a result of the vehicle traveling over a defined road.

17. The method as claimed in claim 12, wherein approximately 70 to 100 force measuring sensors are selected from the plurality of force measuring sensors integrated into the measuring mat and only signals of said selected sensors are further processed, wherein the selected force measuring sensors being preferably arranged in an ischial tuberosity area.

18. The method as claimed in claim 12, wherein, before the step of exciting the system, a checking is carried out to determine whether the actual overall force of all the force measuring sensors corresponds to a set point overall force which is determined in advance for the seat loading body used, the sitting position of the seat loading body on the vehicle seat is corrected until a set point/actual correspondence is brought about.

19. The method as claimed in claim 12, wherein when a person is used as the seat loading body, the measurement of oscillations is not started until the measuring mat has assumed body heat.

20. The method as claimed in claim 16, wherein a measuring journey on said defined road is carried out with straight-ahead travel at a constant speed of approximately 50 to 60 km/h on a dry underlying surface.

21. The method as claimed in claim 20, wherein a measuring journey is carried out over a measuring time of at least approximately 5 minutes.

22. The method as claimed in claim 16, wherein if a straight portion of said of road of approximately 5 km in length is not available, a shorter part of a straight portion of road is traveled over repeatedly backward and forward, the measuring signals and their processing being suppressed during a turning maneuver.

24. The system according to claim 12, further including a test body providing on said flexible mat.

23. A system for determining relative quality of dynamic comfort of upholstered elements of a vehicle seat, said system comprising:

a flexible measuring mat applied to an upholstered seat element in a defined position wherein said flexible measuring mat includes a plurality of forced measuring sensor distributed as a grid to cover a surface of the mat, wherein each of said sensors are flexible and operate without hysteresis to a frequency of approximately 25 Hz and wherein each of said sensors are provided with an output terminal;

an evaluation device connected to received output signals from each of said output of said measuring devices;

an excitation device for oscillating said seat and said measuring mat within a range of frequency between 0 and substantially 30 Hz;

a measuring system for measuring and analyzing outputs of said measuring sensors including means for adding at least approximately within the same phase a force measuring sensor output to form a composite signal and performing a spectral distribution of amplitudes of response oscillations of a system formed by said seat and said mat from the time profile of said composite signals;

means for determining a ratio of an area integral of said frequency response to a specific limit frequency when a limit value of said ratio of the area integral at the limit frequency provides an evaluation number indicating said quality.