ISO 20176:2020
(Main)Road vehicles — H-point machine (HPM-II) — Specifications and procedure for H-point determination
Road vehicles — H-point machine (HPM-II) — Specifications and procedure for H-point determination
This document provides the specifications and procedures for using the H-point machine (HPM)[1] to audit vehicle seating positions. The HPM is a physical tool used to establish key reference points and measurements in a vehicle. The H-point design tool (HPD) is a simplified computer-aided design (CAD)[2] version of the HPM, which can be used in conjunction with the HPM to take the optional measurements specified in this document, or used independently during product design. These H-point devices provide a method for reliable layout and measurement of occupant seating compartments or seats. This document specifies the procedures for installing the H-point machine (HPM) and using the HPM to audit (verify) key reference points and measurements in a vehicle. The devices are intended for application at designated seating positions. They are not to be construed as tools that measure or indicate occupant capabilities or comfort. They are not intended for use in defining or assessing temporary seating, such as folding jump seats. [1] All references to H-point machine or HPM in this document refer to the SAE J4002 H-point machine (HPM-II), unless otherwise noted. [2] CAD has come to encompass any software system or approach to automotive design and development, and is often used to refer to CAE (computer-assisted engineering) and CAM (computer-assisted manufacturing) software systems as well.
Véhicules routiers — Machine point H (HPM-II) — Spécifications et procédure pour la détermination du point H
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 20176
Third edition
2020-09
Road vehicles — H-point machine
(HPM-II) — Specifications and
procedure for H-point determination
Véhicules routiers — Machine point H (HPM-II) — Spécifications et
procédure pour la détermination du point H
Reference number
©
ISO 2020
© ISO 2020
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ii © ISO 2020 – All rights reserved
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Measurement procedure for the three-dimensional H-point machine .3
4.1 General . 3
4.2 Summary of installation procedure . 4
4.2.1 Summary . 4
4.2.2 Measured versus design values . 4
4.3 Prepare vehicle and seat . 4
4.3.1 Vehicle . 4
4.3.2 Seat . 5
4.4 Determine the H-point travel path (optional). 5
4.5 Adjust seat to design intent . 6
4.5.1 Move seat to design intent position . 6
4.5.2 Torso angle and cushion angle . 6
4.5.3 Seat in front of test seat . 7
4.6 Install HPM cushion and back pan assembly . 8
4.6.1 Install the cushion pan . . 8
4.6.2 Install the back pan . . 8
4.6.3 Level the HPM . . . 9
4.7 Load the HPM . 9
4.7.1 Procedure . 9
4.7.2 Summary table . 9
4.7.3 Load the cushion pan .10
4.7.4 Load the back pan .10
4.8 Soak time .11
4.9 Record measurements — digitize HPM points .11
4.9.1 General.11
4.9.2 H-point .11
4.9.3 Torso angle and cushion angle .12
4.9.4 Lumbar support prominence .12
4.9.5 Summary of driver measurements .12
5 Optional measurements for driver seat .12
5.1 Leg and shoe installations .12
5.1.1 General.12
5.1.2 Mark accelerator pedal centreline .13
5.1.3 Install the shoe fixture .13
5.1.4 Install the shoe tool .13
5.1.5 Install leg segments .14
5.2 Record measurements .15
5.2.1 General.15
5.2.2 Shoe plane angle.16
5.2.3 Ball of foot reference point . .16
5.2.4 Accelerator heel point .16
5.2.5 Accelerator heel point to ball of foot reference point lateral offset .18
5.2.6 Knee angle and ankle angle .18
5.2.7 Thigh angle and hip angle .18
6 Optional measurements for the 2nd or succeeding row passenger seats .18
6.1 Leg and shoe installation .18
6.1.1 General.18
6.1.2 Install the shoe tool .18
6.1.3 Install leg segments .20
6.2 Record measurements for rear passengers .22
6.2.1 Summary of measurements .22
6.2.2 Floor reference point .23
6.2.3 Floor plane angle .23
6.2.4 Knee clearance and legroom .23
7 Additional optional measurements .24
7.1 Effective headroom .24
7.1.1 When to install headroom fixture .24
7.1.2 Install the headroom fixture .24
7.1.3 Measure effective headroom .24
8 Remove the HPM .24
Annex A (normative) Description of the three-dimensional H-point machine (HPM) .26
Annex B (informative) HPM specification and tolerances.39
Annex C (informative) HPM field checking procedures .46
Annex D (informative) H-point design (HPD) tool description .63
Bibliography .67
iv © ISO 2020 – All rights reserved
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 39,
Ergonomics.
This third edition cancels and replaces the second edition (ISO 20176:2011), of which it constitutes a
minor revision. The changes compared to the previous edition are as follows:
— minor editorial changes;
— removal of reference to the cancellation and replacement of ISO 6549:1999.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
Introduction
The tools and procedures for H-point determination given in this document are based on SAE J4002.
H-point devices are used during vehicle design and development to establish interior reference points
and dimensions for occupant packaging, and to validate the location of these key reference points and
dimensions on physical properties during audits.
H-point devices are also used for the design and validation of seats. However, in these instances, the
reference points and dimensions are defined relative to the seat structure or surface, rather than the
vehicle's interior. The procedures for positioning the H-point devices in seats do not require the use of
the shoe tool or leg segments.
For convenience and simplicity, many terms associated with H-point devices use human body parts in
their name. However, they should not be construed as measures that indicate occupant accommodation,
human capabilities, or comfort. H-point devices do not represent the size or posture of any category of
occupant.
Key differences from ISO 6549
Compared to the H-point machine (HPM) specified in ISO 6549, the HPM specified in this
document provides improved repeatability, greater ease of use, as well as additional features and
measurement capabilities. All efforts were made to achieve these improvements while minimizing
their impact on the location of reference points and measurements. Several of the changes are
discussed below.
1) Separate components
For this HPM, the legs (upper and lower), shoe, cushion pan and back pan are all separate
pieces. This greatly improves the ease of installation.
2) “Legless” manikin
The H-point location is defined without having to attach the legs. This is a major
advantage. The procedure specified in this document is based on installing the HPM without
legs. Use of legs is optional.
3) Shoe tool
Several improvements were made to the shoe tool and how it is positioned in the vehicle,
including:
i) replacing the pedal reference point (PRP) with a new ball of foot reference point (BOFRP);
ii) specifying a new procedure for positioning the shoe on the pedal.
4) Cushion angle
The cushion angle is now measured independently of thigh angle, and at the same time
the other measurements are made. With the ISO 6549 HPM, cushion angle was measured from
the thigh line, and required a separate installation of the HPM.
5) Lumbar support
The articulation of the back pan assembly allows the HPM specified in this document to be
better seated in contoured seats. It also provides a measurement of lumbar support prominence
(LSP). This measurement provides an indication of the amount the seat back is contoured to
provide support for the lumbar spine. The contour of the back pan assembly is most similar to
the ISO 6549 H-point machine when the HPM is in a neutral posture (LSP equals zero).
vi © ISO 2020 – All rights reserved
Changes from ISO 20176:2011
The procedures for auditing the seat are unchanged from the second edition.
In the second edition, the most significant change was that the ball of foot (BOF) of the shoe does
not have to be on the pedal surface. The HPM shoe can contact the pedal at any point(s) on the
bottom of the shoe. The term pedal reference point (PRP) was deleted (since the BOF may not
be on the pedal) and replaced by a new term called the ball of foot reference point (BOFRP). The
accelerator heel point (AHP) to BOF distance was changed from 200 mm to 203 mm to be consistent
with ISO 6549, SAE J1100, and vehicle manufacturers around the world.
In addition, the following physical modifications were made to the HPM. The flat part of the shoe
bottom was extended from 200 mm to 203 mm. A new scale was added to the top of the shoe to aid
in determining the pedal contact point (PCP). A new H-point divot was added to allow coordinate
measuring machine (CMM) point taking from above. The knee angle scale was recessed to improve
its durability and reoriented to improve its readability. Several figures were revised to illustrate
these changes.
Finally, the terms pedal plane and pedal plane angle (PPA) were replaced by shoe plane and shoe
plane angle (SPA). These new terms more accurately convey the meaning. SPA is a side view angle
that is provided by the vehicle manufacturer.
INTERNATIONAL STANDARD ISO 20176:2020(E)
Road vehicles — H-point machine (HPM-II) —
Specifications and procedure for H-point determination
1 Scope
1)
This document provides the specifications and procedures for using the H-point machine (HPM) to
audit vehicle seating positions. The HPM is a physical tool used to establish key reference points and
2)
measurements in a vehicle. The H-point design tool (HPD) is a simplified computer-aided design (CAD)
version of the HPM, which can be used in conjunction with the HPM to take the optional measurements
specified in this document, or used independently during product design.
These H-point devices provide a method for reliable layout and measurement of occupant seating
compartments or seats. This document specifies the procedures for installing the H-point machine
(HPM) and using the HPM to audit (verify) key reference points and measurements in a vehicle.
The devices are intended for application at designated seating positions. They are not to be construed
as tools that measure or indicate occupant capabilities or comfort. They are not intended for use in
defining or assessing temporary seating, such as folding jump seats.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 4130, Road vehicles — Three-dimensional reference system and fiducial marks — Definitions
SAE J1100, Motor vehicle dimensions
SAE J4002, H-point machine (HPM-II) specifications and procedure for H-point determination — Auditing
vehicle seats
3 Terms and definitions
For the purposes of this document, the terms and definitions given in SAE J1100 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
H-point
point at the pivot centre of the back pan and cushion pan assemblies, located on the lateral centreline of
the H-point device
Note 1 to entry: The H-point device can be the H-point machine (HPM) or the H-point design tool (HPD).
1) All references to H-point machine or HPM in this document refer to the SAE J4002 H-point machine (HPM-II),
unless otherwise noted.
2) CAD has come to encompass any software system or approach to automotive design and development, and is
often used to refer to CAE (computer-assisted engineering) and CAM (computer-assisted manufacturing) software
systems as well.
Note 2 to entry: The H-point is also the intersection of the cushion line and the torso line. When an H-point device
is properly positioned within a vehicle, either in CAD or in an actual physical property, the location of the H-point
relative to the vehicle is used as a vehicle reference point. If the seat is moved, the location of the H-point within
the vehicle is changed. Therefore, adjustable seats have more than one H-point location, while fixed seats have
only one H-point location.
Note 3 to entry: H-points are often referred to as hip points or hip pivot points. They simulate, but do not precisely
represent, the location of the human hip joint.
3.2
H-point travel path
all possible locations of the H-point (3.1) provided by the full range of seat adjustments (horizontal,
vertical or tilt) for a given designated seating position
3.3
seating reference point
SgRP
R-point
manufacturer's intended location for a design H-point (3.1), which is specifically designated as R-point
or SgRP, and which:
a) is the fundamental reference point used to establish occupant accommodation tools and
dimensions;
b) simulates the position of the pivot centre of the human torso and thigh;
c) has coordinates established with respect to the designed vehicle structure;
d) establishes the rearmost normal design driving or riding H-point of each designated seating
position, which accounts for all modes of adjustment, horizontal, vertical and tilt that are available
for the seat, but does not include seat travel used for purposes other than normal driving and riding
Note 1 to entry: The SgRP is sometimes referred to as the design H-point.
3.4
accelerator heel point
AHP
point representing the heel of shoe location on the depressed floor covering, when the bottom of shoe is
in contact with the undepressed accelerator pedal and the ankle angle is at 87°
Note 1 to entry: The lateral location ( y-coordinate) is aligned with the BOFRP (3.5) unless shoe interference with
side support structure causes an offset of the AHP from the BOFRP (see 5.1.4.2).
3.5
ball of foot reference point
BOFRP
point representing the ball of foot location on the shoe plane when the H-point (3.1) machine shoe is set
to a specified shoe plane angle (3.8), the bottom of shoe is in contact with the undepressed accelerator
pedal, the ball of foot is aligned with the lateral centreline of the undepressed accelerator pedal in rear
view, and the heel of shoe is at the depressed floor covering
Note 1 to entry: The BOFRP and AHP (3.4) are at the same y-coordinate unless there is lateral shoe interference.
3.6
floor reference point
FRP
point at the intersection of the heel of shoe and the depressed floor covering, with the
bottom of shoe resting on the depressed floor covering
Note 1 to entry: FRP is determined within 127 mm to either side of centreline of occupant, with the shoe or lower
leg segment moved forward to rest against the seat in front (contacting the underseat structure, lower portion of
the seat back trim, etc.).
2 © ISO 2020 – All rights reserved
3.7
lumbar support prominence
LSP
measure of the back-pan shape imposed on the HPM by the contour of the lower seatback
Note 1 to entry: See Table A.4.
3.8
shoe plane angle
SPA
α
SP
angle from horizontal to the bottom of the HPM shoe when the shoe is in contact with the undepressed
accelerator pedal and the shoe heel is at the AHP (3.4)
Note 1 to entry: SPA is provided by the vehicle manufacturer or calculated from the manufacturer's published
seat height H30-1 (see 5.1.4).
4 Measurement procedure for the three-dimensional H-point machine
4.1 General
A complete description of the three-dimensional H-point machine is given in Annex A (see Figure 1).
Specifications and tolerances are given in Annex B. A field checking procedure for the HPM is given in
Annex C.
Figure 1 — Side view of HPM, including optional components
3)
The HPM includes divot points that can be used by a coordinate measuring machine (CMM) and in
4)
CAD to fully define the location of the machine in the vehicle space (see A.2.3). Calibrated planar
surfaces on the HPM facilitate field measurement of machine angles using an inclinometer. A scale
readout indicates the lumbar support prominence (LSP) value. An ankle angle scale is provided to aid
HPM installation in long-coupled passenger seating.
3) All references to H-point machine or HPM in this document refer to the SAE J4002 H-point machine (HPM-II),
unless otherwise noted.
4) CAD has come to encompass any software system or approach to automotive design and development, and is
often used to refer to CAE (computer-assisted engineering) and CAM (computer-assisted manufacturing) software
systems as well.
Several of the reference points established with an H-point device are required for the subsequent
positioning of other design devices, such as head contours, eyellipses and reach curves. The most
important reference points established by an H-point device are the H-point, the H-point travel path,
the seating reference point (SgRP), the accelerator heel point (AHP), and the ball of foot reference point
(BOFRP). These reference points are illustrated in Figure A.8.
4.2 Summary of installation procedure
4.2.1 Summary
See Table 1.
Table 1 — Summary of installation procedure
Driver position Passenger positions: 2nd and 3rd row
Prepare the physical property. If possible, calibrate the CMM equipment to vehicle grid coordinates.
Position the test seat and (if the HPM legs are to be
Position seat to design intent location and attitude. installed) the seat in front of the test seat to design
intent location and attitude.
Install shoe fixture and shoe tool, if measuring leg and
Install shoe tool, if measuring leg and shoe dimensions.
shoe dimensions. Record shoe-based
Record shoe-based measurements. See 6.1.
measurements. See 5.1.
Install and load the cushion pan and back pan.
If measuring headroom, install headroom fixture before loading the pans. See 7.1.
Determine H-point, torso angle, cushion angle and LSP. See 4.8.
Attach thigh and lower leg segments, if measuring Attach thigh and lower leg segments, if measuring
leg-based dimensions. See 5.1. leg-based dimensions. See 6.1.
Determine optional measurements. See 5.2 and 7.1. Determine optional measurements. See 6.2 and 7.1.
4.2.2 Measured versus design values
When verifying or auditing a particular designated vehicle seating position, measurements taken
with the three-dimensional HPM are normally compared to the design values indicated by the vehicle
manufacturer. If any measured value is sufficiently close to the manufacturer's design value, the vehicle
or seat is considered to meet the manufacturer's design intent for that measurement. The vehicle
manufacturer or a regulatory agency may provide specifications for the term “sufficiently close”. Two
HPM measurements of particular interest are H-point (SgRP) and torso angle.
4.3 Prepare vehicle and seat
4.3.1 Vehicle
Dimensions shall be measured relative to the vehicle three-dimensional reference system by setting up
the vehicle relative to the fiducial marks in accordance with ISO 4130 as specified by the manufacturer.
The vehicle (or seating buck) shall be levelled prior to any HPM installation or measurement. Once the
vehicle is levelled, care should be taken to not lean on it, rock it, or in some other way knock it off level.
If the accelerator pedal is needed for the measurements, the accelerator pedal shall be held in an
undepressed position by some means. For example, use blocks or clamp the accelerator cable to prevent
the pedal from moving. If the pedal rotates about a pivot, independent of throttle movement, do not
restrict that motion. If the accelerator pedal has fore/aft adjustment, the pedal shall be positioned as
specified by the manufacturer. If no specification is provided, the pedal shall be adjusted to its most
forward position in the vehicle.
4 © ISO 2020 – All rights reserved
4.3.2 Seat
The vehicle shall be preconditioned at the manufacturer's discretion, at a temperature of 19 °C to 26 °C
to ensure that the seat material reaches room temperature. Room relative humidity should be within
50 % ± 5 %. If this relative humidity is not met, record both relative humidity and room temperature.
The following considerations are to help ensure that stable, reliable measurements are made across
seat types. If the seat to be checked has never been sat upon, a 70 kg to 80 kg person or device shall be
placed on the seat to flex the cushion and back. Prior to the installation of the HPM, seats should remain
unloaded for 30 min at the manufacturer's request. This is to allow the seat and seat materials (e.g.
foam) to recover from compression.
Muslin cloth should be placed over the seat prior to installing the HPM. The muslin cloth may be a single
piece fitting across both seat cushion and seat back, or two pieces, one for the cushion and one for the
seat back. This ensures a constant friction surface across seat fabrics. See B.11.
When using the HPM, interactions can occur between adjacent seating positions (i.e. having an HPM
installed at the centre occupant position can change the results obtained for the outboard occupant
position). Therefore, only one machine should be installed in a particular row of seats during each test.
4.4 Determine the H-point travel path (optional)
If verification of the H-point travel path is desired, the seat's travel path shall be digitized and then
translated to the H-point travel path. First, adjust the seat cushion to the middle of the cushion angle
adjustment range. Next, place one or more registration marks on the side of the seat. The registration
mark(s) can be located anywhere along the side of the seat that can be easily accessed by the CMM
equipment. Finally, digitize the location of the registration mark(s) with the seat in each of four
positions: lowest most-rearward, highest most-rearward, highest most-forward, lowest most-forward.
By connecting these four points, the seat's travel path can be seen more readily. See Figure 2 a) and b).
NOTE For seats without vertical adjustment, only two points are taken, most forward and most rearward,
provided the seat track follows a linear path. If the seat track travel path is curved, additional points (between
foremost and rearmost) are taken.
a) Place registration b) Move seat through c) Translate seat travel d) Move seat by (x ,z )
1 1
mark on seat with seat its fore/aft and up/ path by (x,z) to get the from lowest, most-rear-
at lowest most-rear- down travel path H-point travel path ward H-point to its
ward position SgRP location
Key
1 registration mark
2 registration mark at extremes of seat travel
3 lowest, most-rearward H-point
4 SgRP
Figure 2 — Locating seating reference point from the seat travel path
4.5 Adjust seat to design intent
4.5.1 Move seat to design intent position
All adjustable features of the seat shall be set to manufacturer's design intent attitude or position before
installing the HPM.
For seats with an independent vertical adjustment or suspension, the vertical position shall be rigidly
fixed in a position specified by the manufacturer.
The seat registration mark is helpful in positioning the seat at design intent relative to one of the seat's
extreme locations (usually the rearmost, lowest position) determined in 4.4. Normally, the design
intent position specified by the vehicle manufacturer is the SgRP. Figure 2 illustrates a typical way to
translate seat travel to H-point travel and then to SgRP. After an adjustable seat is positioned at design
intent, digitize the seat registration mark(s).
4.5.2 Torso angle and cushion angle
4.5.2.1 General
Seat torso and cushion angle adjustment procedures for auditing differ depending on whether or not
variance in seat build is of interest.
4.5.2.2 Standard audit: include seat and vehicle build variability
The seat shall be adjusted to the design intent torso angle and cushion angle before installing the
HPM. The vehicle manufacturer (or seat supplier) shall provide information regarding the location and
attitude of the discernible seat structure (e.g. the seat frame), other hard points (e.g. seat controls, pivot
points, head restraint rods), or the amount of adjustment required to attain the desired seat attitude.
4.5.2.3 Optional audit: exclude seat build variability
If the purpose of the audit is to evaluate the build of the vehicle package without accounting for seat
build variability, then the HPM needs to be installed in order to set the seat to the design intent values
of torso and cushion angles.
As the HPM is loaded with weights, torso angle tends to increase and cushion angle tends to decrease.
If torso and cushion angles are adjustable, the initial (unloaded) angles usually differ by about 1° to
2° from the desired final angles after loading. For example, set the seat back initially to an angle of
approximately 20° to achieve a final torso angle of 22°.
Monitor and readjust torso and cushion angles as necessary during installation of HPM weights in order
to achieve the design intent angles as the final reading (see Table 2). Then, remove the HPM, wait 30 min
to allow the seat materials to recover, and install the HPM a second time for the audit. For this audit, the
HPM installation normally includes the leg and shoe tool, as well as the headroom fixture.
NOTE The seat can also be audited independently of the vehicle.
6 © ISO 2020 – All rights reserved
Table 2 — Optional audit: Adjusting torso and cushion angles during HPM loading
Angle Driver position Passenger positions: 2nd or 3rd row
If the seat recliner is adjustable, initially set
Initially set the torso angle to approximate-
the torso angle to approximately 2° more
Torso angle ly 2° more vertical than the design intent.
vertical than the design intent. Monitor
A40 Monitor and adjust if needed during HPM
and adjust if needed during HPM loading to
loading to achieve design intent.
achieve design intent.
If the seat cushion is adjustable, initially set the cushion angle to be slightly greater than
Cushion angle
design intent value. Monitor and readjust as necessary during HPM installation to achieve
A27
the design intent cushion angle as the final reading.
Key
1 handle 10 thoracic segment
2 torso articulation locking lever 11 B2 divot
3 inclinometer lands for torso angle 12 articulation mechanism
4 head room fixture tumbler 13 lumbar segment
5 lumbar support prominence (LSP) scale 14 lower weight rack (left side)
6 load application point 15 pelvic segment
7 indicator to read LSP value 16 H-point pivot shaft
8 B1 divot 17 one of twelve back weights
9 upper weight rack (left side)
Figure 3 — Back pan
4.5.3 Seat in front of test seat
If leg positions, legroom, footroom and knee clearance are to be measured, the seat in front of the test
seat should be positioned to its SgRP and design intent torso angle.
4.6 Install HPM cushion and back pan assembly
4.6.1 Install the cushion pan
Place the cushion pan (see Figure 4) on the seat with the back of the pan resting lightly against the seat
back. Visually centre the cushion pan laterally in the seat.
Key
1 thigh weight locating pins (4)
2 handle
3 load application point
4 C1 divot
5 inclinometer land for cushion angle
6 lateral level
7 H-point saddle
8 H1R divot
9 H1L divot
10 locking bushings for attaching back pan (2), thigh segment (2) and headroom fixture
11 H2L divot
12 thigh weight (6)
13 pelvic weight (6)
Figure 4 — Cushion pan
4.6.2 Install the back pan
To protect the shells of the cushion and back pans, the back pan should be locked in a slouched position
before installing it. Articulate the back pan into a slouched position (LSP < 0) and lock.
8 © ISO 2020 – All rights reserved
Place the H-point pivot shaft, located at the base of the back pan, on the H-point saddle of the cushion
pan (see Figures 3 and 4). The upper portions of the back pan should not contact the seat back. Secure
by sliding the brass locking bushings inwards over the H-point shaft.
Unlock the torso articulation. Put one hand firmly on the cushion pan T-handle to maintain the position
of the cushion pan. Put the other hand on the back pan T-handle and gently rotate the back pan assembly
against the seat back to allow the back pan assembly to conform to the seat back contour. Ensure that
the top and bottom corners at each side of the lumbar segment remain outside the thoracic and pelvic
segments. Also ensure that the muslin cloth is not caught between the back segments (see Figure 5).
The cushion and back pan can be connected and installed as a single unit if preferred. Follow the same
steps as above, centring the cushion pan lightly against the seat back with the back pan rotated forward
and locked in the slouched position.
If measuring headroom, install the headroom fixture now (see 7.1).
4.6.3 Level the HPM
Referring to the bubble level on the cushion pan, dither and adjust the HPM so it is level laterally on the
seat. Make sure the HPM is in firm contact with the seat back.
4.7 Load the HPM
4.7.1 Procedure
Installing weights on the HPM is referred to as ‘loading'. The HPM shall be loaded with the torso
articulation mechanism unlocked. Weights shall be installed from the H-point outward and from the
H-point upward to prevent the HPM from toppling out of the seat. Prior to each round of weights being
loaded, an 89 N force shall be applied twice by ‘punching' the appropriate load application site with the
spring-loaded probe. The operator shall immediately release any applied force once the punch probe
reaches its spring loading. This procedure ensures the HPM remains fully nested into the seat during
the loading.
4.7.2 Summary table
The HPM shall be checked for level during the loading process. The sequence of actions for loading the
HPM, summarized in Table 3, shall be followed.
Table 3 — Loading the HPM
Round Apply 89 N Load two weights Then load two weights Check for:
Punch twice
1 2 Pelvic — innermost positions 2 Thigh Level
(cushion)
Punch twice
2 2 Pelvic — next innermost positions 2 Thigh Level
(cushion)
Punch twice 2 Bevelled pelvic — outermost
3 2 Thigh Level
(cushion) positions
Punch twice
4 2 Lower rack — innermost positions 2 Upper rack — innermost positions Level
(back)
Punch twice 2 Lower rack — next innermost 2 Upper rack — next innermost
5 Level
(back) position positions
Punch twice
6 2 Lower rack — outermost positions 2 Upper rack — outermost positions Level
(back)
7 Lock torso articulation
4.7.3 Load the cushion pan
There are two types of weights for loading the cushion pan: pelvic weights, which are positioned in
slots along the H-point axis, and thigh weights that are held in place by the pins in the thigh area.
Punch the HPM twice at the cushion pan load application point (see Figure 5). Install two pelvic weights
in the innermost pelvic weight slots (one to either side of the H-point). Install two thigh weights (one to
either side). Check for level.
Repeat these steps (punch twice, load two pelvic weights, load two thigh weights, and level) two more
times to complete the loading of the cushion pan.
4.7.4 Load the back pan
There are two areas for loading weights on the back-pan assembly, the lower and upper racks. However,
the same type of weight is used in both areas.
When auditing the vehicle, but not the seat build, adjust the seat cushion or seat back recliner if
necessary during the loading to obtain a final cushion and torso angle that equals design intent (see
4.5.2.3). The adjustments should be made after checking the cushion or back pan for level in each round
shown in Table 3.
Punch the HPM twice at the back-pan load application point (see Figure 5). Install two weights on the
lower racks–one on either side of centreline. Push the weights toward the centreline as far as possible.
Install two weights on the upper racks, one on either side of centreline, and push towards the centreline.
Check for level.
Repeat these steps (punch twice, load two weights on the lower rack, load two weights on the upper
rack, and level) two more times.
After the back pan is fully loaded and level, lock the torso articulation mechanism.
10 © ISO 2020 – All righ
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