PROCEDURE FOR DETERMINING THE "H" POINT AND THE ACTUAL
TORSO ANGLE FOR SEATING POSITIONS IN MOTOR VEHICLES
PURPOSE
The procedure described in this annex is used to establish the "H" point location and the actual torso angle for one or several seating positions in a motor vehicle and to verify the relationship of measured data to design specifications given by the vehicle manufacturer. [1]/
DEFINITIONS
For the purposes of this annex:
2.1. "Reference data" means one or several of the following characteristics of a seating position:
2.1.1. the "H" point and the "R" point and their relationship,
2.1.2. the actual torso angle and the design torso angle and their relationship.
2.2. "Three‑dimensional 'H' point machine" (3‑D H machine) means the device used for the determination of "H" points and actual torso angles. This device is described in Appendix 1 to this annex;
2.3. " 'H' point" means the pivot centre of the torso and the thigh of the 3‑D H machine installed in the vehicle seat in accordance with paragraph 4 below. The "H" point is located in the centre of the centreline of the device which is between the "H" point sight buttons on either side of the 3‑D H machine. The "H" point corresponds theoretically to the "R" point (for tolerances see paragraph 3.2.2. below). Once determined in accordance with the procedure described in paragraph 4., the "H" point is considered fixed in relation to the seat‑cushion structure and to move with it when the seat is adjusted;
2.4. " 'R' point" or "seating reference point" means a design point defined by the vehicle manufacturer for each seating position and established with respect to the three‑dimensional reference system;
2.5. "Torso‑line" means the centreline of the probe of the 3‑D H machine with the probe in the fully rearward position;
2.6. "Actual torso angle" means the angle measured between a vertical line through the "H" point and the torso line using the back angle quadrant on the 3‑D H machine. The actual torso angle corresponds theoretically to the design torso angle (for tolerances see paragraph 3.2.2. below):
2.7. "Design torso angle" means the angle measures between a vertical line through the "R" point and the torso line in a position which corresponds to the design position of the seat‑back established by the vehicle manufacturer;
2.8. "Centreplane of occupant" (C/LO) means the median plane of the 3‑D H machine positioned in each designated seating position; it is represented by the co‑ordinate of the "H" point on the "Y" axis. For individual seats, the centreplane of the seat coincides with the centreplane of the occupant. For other seats, the centreplane of the occupant is specified by the manufacturer;
2.9. "Three‑dimensional reference system" means a system as described in Appendix 2 to this annex;
2.10. "Fiducial marks" are physical points (holes, surfaces, marks or indentations) on the vehicle body as defined by the manufacturer;
2.11. "Vehicle measuring attitude" means the position of the vehicle as defined by the co‑ordinates of fiducial marks in the three‑dimensional reference system.
REQUIREMENTS
3.1. Data presentation
For each seating position where reference data are required in order to demonstrate compliance with the provisions of the present Regulation, all or an appropriate selection of the following data shall be presented in the form indicated in Appendix 3 to this annex:
3.1.1. the co‑ordinates of the "R" point relative to the three‑dimensional reference system;
3.1.2. the design torso angle;
3.1.3. all indications necessary to adjust the seat (if it is adjustable) to the measuring position set out in paragraph 4.3. below.
3.2. Relationship between measured data and design specifications
3.2.1. The co‑ordinates of the "H" point and the value of the actual torso angle obtained by the procedure set out in paragraph 4. below shall be compared, respectively, with the co‑ordinates of the "R" point and the value of the design torso angle indicated by the vehicle manufacturer.
3.2.2. The relative positions of the "R" point and the "H" point and the relationship between the design torso angle and the actual torso angle shall be considered satisfactory for the seating position in question if the "H" point, as defined by its co‑ordinates, lies within a square of 50 mm side length with horizontal and vertical sides whose diagonals intersect at the "R" point, and if the actual torso angle is within 5° of the design torso angle.
3.2.3. If these conditions are met, the "R" point and the design torso angle, shall be used to demonstrate compliance with the provisions of this Regulation.
3.2.4. If the "H" point or the actual torso angle does not satisfy the requirements of paragraph 3.2.2. above, the "H" point and the actual torso angle shall be determined twice more (three times in all). If the results of two of these three operations satisfy the requirements, the conditions of paragraph 3.2.3. above shall apply.
3.2.5. If the results of at least two of the three operations described in paragraph 3.2.4. above do not satisfy the requirements of paragraph 3.2.2. above, or if the verification cannot take place because the vehicle manufacturer has failed to supply information regarding the position of the "R" point or regarding the design torso angle, the centroid of the three measured points or the average of the three measured angles shall be used and be regarded as applicable in all cases where the "R" point or the design torso angle is referred to in this Regulation.
PROCEDURE FOR "H" POINT AND ACTUAL TORSO ANGLE DETERMINATION
4.1. The vehicle shall be preconditioned at the manufacturer's discretion, at a temperature of 20 + 10 °C to ensure that the seat material reached room temperature. If the seat to be checked has never been sat upon, a 70 to 80 kg person or device shall sit on the seat twice for one minute to flex the cushion and back. At the manufacturer's request, all seat assemblies shall remain unloaded for a minimum period of 30 minutes prior to installation of the 3‑D H machine.
4.2. The vehicle shall be at the measuring attitude defined in paragraph 2.11. above.
4.3. The seat, if it is adjustable, shall be adjusted first to the rearmost normal driving or riding position, as indicated by the vehicle manufacturer, taking into consideration only the longitudinal adjustment of the seat, excluding seat travel used for purposes other than normal driving or riding positions. Where other modes of seat adjustment exist (vertical, angular, seat‑back, etc.) these will then be adjusted to the position specified by the vehicle manufacturer. For suspension seats, the vertical position shall be rigidly fixed corresponding to a normal driving position as specified by the manufacturer.
4.4. The area of the seating position contacted by the 3‑D H machine shall be covered by a muslin cotton, of sufficient size and appropriate texture, described as a plain cotton fabric having 18.9 threads per cm2 and weighing 0.228 kg/m2 or knitted or non‑woven fabric having equivalent characteristics. If the test is run on a seat outside the vehicle, the floor on which the seat is placed shall have the same essential characteristics [2]/ as the floor of the vehicle in which the seat is intended to be used.
4.5. Place the seat and back assembly of the 3‑D H machine so that the centreplane of the occupant (C/LO) coincides with the centreplane of the 3‑D H machine. At the manufacturer's request, the 3‑D H machine may be moved inboard with respect to the C/LO if the 3‑D H machine is located so far outboard that the seat edge will not permit levelling of the 3‑D H machine.
4.6. Attach the foot and lower leg assemblies to the seat pan assembly, either individually or by using the T‑bar and lower leg assembly. A line through the "H" point sight buttons shall be parallel to the ground and perpendicular to the longitudinal centreplane of the seat.
4.7. Adjust the feet and leg positions of the 3‑D H machine as follows:
4.7.1. Designated seating position: driver and outside front passenger
4.7.1.1. Both feet and leg assemblies shall be moved forward in such a way that the feet take up natural positions on the floor, between the operating pedals if necessary. Where possible the left foot shall be located approximately the same distance to the left of the centreplane of the 3‑D H machine as the right foot is to the right. The spirit level verifying the transverse orientation of the 3‑D H machine is brought to the horizontal by readjustment of the seat pan if necessary, or by adjusting the leg and foot assemblies towards the rear. The line passing through the "H" point sight buttons shall be maintained perpendicular to the longitudinal centreplane of the seat.
4.7.1.2. If the left leg cannot be kept parallel to the right leg and the left foot cannot be supported by the structure, move the left foot until it is supported. The alignment of the sight buttons shall be maintained.
4.7.2. Designated seating position: outboard rear
For rear seats or auxiliary seats, the legs are located as specified by the manufacturer. If the feet then rest on parts of the floor which are at different levels, the foot which first comes into contact with the front seat shall serve as a reference and the other foot shall be so arranged that the spirit level giving the transverse orientation of the seat of the device indicates the horizontal.
4.7.3. Other designated seating positions:
The general procedure indicated in paragraph 4.7.1. above shall be followed except that the feet shall be placed as specified by the vehicle manufacturer.
4.8. Apply lower leg and thigh weights and level the 3‑D H machine.
4.9. Tilt the back pan forward against the forward stop and draw the 3‑D H machine away from the seat‑back using the T‑bar. Reposition the 3‑D H machine on the seat by one of the following methods:
4.9.1. If the 3‑D H machine tends to slide rearward, use the following procedure. Allow the 3‑D H machine to slide rearward until a forward horizontal restraining load on the T‑bar is no longer required i.e. until the seat pan contacts the seat‑back. If necessary, reposition the lower leg.
4.9.2. If the 3‑D H machine does not tend to slide rearward, use the following procedure. Slide the 3‑D H machine rearwards by applying a horizontal rearward load to the T‑bar until the seat pan contacts the seat‑back (see figure 2 of Appendix 1 to this annex).
4.10. Apply a 100 + 10 N load to the back and pan assembly of the 3‑D H machine at the intersection of the hip angle quadrant and the T‑bar housing. The direction of load application shall be maintained along a line passing by the above intersection to a point just above the thigh bar housing (see figure 2 of Appendix 1 to this annex). Then carefully return the back pan to the seat‑back. Care must be exercised throughout the remainder of the procedure to prevent the 3‑D H machine from sliding forward.
4.11. Install the right and left buttock weights and then, alternately, the eight torso weights. Maintain the 3‑D H machine level.
4.12. Tilt the back pan forward to release the tension on the seat‑back. Rock the 3‑D H machine from side to side through a 10° arc (5° to each side of the vertical centreplane) for three complete cycles to release any accumulated friction between the 3‑D H machine and the seat.
During the rocking action, the T‑bar of the 3‑D H machine may tend to diverge from the specified horizontal and vertical alignment. The T‑bar must therefore be restrained by applying an appropriate lateral load during the rocking motions. Care shall be exercised in holding the T‑bar and rocking the 3‑D H machine to ensure that no inadvertent exterior loads are applied in a vertical or fore and aft direction.
The feet of the 3‑D H machine are not to be restrained or held during this step. If the feet change position, they should be allowed to remain in that attitude for the moment.
Carefully return the back pan to the seat‑back and check the two spirit levels for zero position. If any movement of the feet has occurred during the rocking operation of the 3‑D H machine, they must be repositioned as follows:
Alternately, lift each foot off the floor the minimum necessary amount until no additional foot movement is obtained. During this lifting, the feet are to be free to rotate; and no forward or lateral loads are to be applied. When each foot is placed back in the down position, the heel is to be in contact with the structure designed for this.
Check the lateral spirit level for zero position; if necessary, apply a lateral load to the top of the back pan sufficient to level the 3‑D H machine's seat pan on the seat.
4.13. Holding the T‑bar to prevent the 3‑D H machine from sliding forward on the seat cushion, proceed as follows:
(a) return the back pan to the seat‑back;
(b) alternately apply and release a horizontal rearward load, not to exceed 25 N, to the back angle bar at a height approximately at the centre of the torso weights until the hip angle quadrant indicates that a stable position has been reached after load release. Care shall be exercised to ensure that no exterior downward or lateral loads are applied to the 3‑D H machine. If another level adjustment of the 3‑D H machine is necessary, rotate the back pan forward, re‑level, and repeat the procedure from paragraph 4.12.
4.14. Take all measurements:
4.14.1. The co‑ordinates of the "H" point are measured with respect to the three‑dimensional reference system.
4.14.2. The actual torso angle is read at the back angle quadrant of the 3‑D H machine with the probe in its fully rearward position.
4.15. If a re‑run of the installation of the 3‑D H machine is desired the seat assembly should remain unloaded for a minimum period of 30 minutes prior to the re‑run. The 3‑D H machine should not be left loaded on the seat assembly longer than the time required to perform the test.
4.16. If the seats in the same row can be regarded as similar (bench seat, identical seats, etc.) only one "H" point and one "actual torso angle" shall be determined for each row of seats, the 3‑D H machine described in Appendix 1 to this annex being seated in a place regarded as representative for the row. This place shall be:
4.16.1. in the case of the front row, the driver's seat;
4.16.2. in the case of the rear row or rows, an outer seat.