4. Dummy Positioning and Belt Routing for Full-Width Frontal Passenger

Passenger-Side Occupant Setup: Scope and Constraints

This case positions a Hybrid III 50th percentile male (HIII-50M) in the front passenger seat of a full-width frontal (rigid barrier) crash model and routes the three-point seatbelt so that restraint interaction is physically credible before the run starts. The driver-side equivalent is handled elsewhere; the passenger side differs in three ways that matter for setup: the seat track and cushion geometry are asymmetric, the belt buckle is on the inboard side (right-hand buckle stalk for a left-hand-drive vehicle), and the passenger seat typically carries a different fore-aft position and recline angle in the test specification. Getting these wrong produces belt-to-dummy gaps, shoulder-belt migration off the clavicle, or a submarining-prone lap path — all of which corrupt chest deflection and femur load readings long before the barrier is reached.

The task closes when four conditions hold: the dummy's H-point matches the specification within tolerance, the pelvis and torso angles match the target posture, the belt webbing lies in contact with the dummy along the specified path with no initial penetration, and a short settling run shows no belt element snapping or dummy drift. Everything below is organized around reaching and proving those four conditions.

Reference Frame and Sign Conventions

All coordinates in this case use the vehicle coordinate system: X positive forward (toward the barrier), Y positive to the vehicle's left, Z positive upward, origin at the vehicle datum on the centerline at ground level. Seat track travel is measured along X; recline is a rotation about the Y axis, positive when the seatback tilts rearward. Belt anchor positions are given in the same frame. Keep this convention consistent across the dummy positioning card, the belt routing nodes, and the SVG below — mixing a dummy-local frame with the vehicle frame is the single most common source of a mirrored or offset occupant.

Positioning the Dummy to the Specification Card

Start from the seat, not the dummy. Set the passenger seat track to the specified position and the seatback to its specified recline angle, then place the dummy so its H-point coincides with the seat's design H-point. A practical sequence for a rigid-seat model:

1. Set seat track to X = 120 mm rearward of full-forward and recline to 25° from vertical (example values — substitute the values from your test specification card).
2. Translate the dummy so the H-point node sits at the seat design H-point, then rotate about Y to the target pelvis angle (typically 20–23° for HIII-50M in a frontal test).
3. Set the torso angle by rotating the upper torso relative to the pelvis to the specified value (commonly 22–25° from vertical for the passenger side).
4. Set head angle to the specified value and confirm the head is not pre-contacting the head restraint or the A-pillar trim.
5. Set knee and ankle angles so the feet rest flat on the toeboard with the specified heel point; do not let the feet float or pre-load the toeboard.

After each change, re-check the H-point. Rotating the torso or moving the legs can shift the pelvis if the dummy is not constrained, so lock the pelvis translation before adjusting the upper body.

Routing the Three-Point Belt

The passenger belt runs from the outboard D-ring (shoulder anchor) down across the chest to the inboard buckle stalk, and the lap portion runs from the outboard retractor/anchor across the pelvis to the same buckle. Route the webbing as a chain of belt elements through, not around, the dummy:

• Shoulder segment: passes over the outboard clavicle, crosses the sternum, and enters the buckle. It must contact the chest surface along its length; a gap larger than a few millimeters at the clavicle lets the belt slip outboard during the crash.
• Lap segment: lies across the anterior superior iliac spine (ASIS) region, low on the pelvis, not across the abdomen. A lap belt riding above the ASIS is the classic submarining precursor.
• Buckle stalk: position the buckle so the latch plate sits at the specified location relative to the dummy's inboard hip; adjust the stalk angle rather than stretching the webbing.

Adjust the D-ring height and the outboard anchor so the shoulder belt passes over the mid-clavicle, and adjust the buckle stalk so the lap belt sits at the specified height on the pelvis. These are the two anchor adjustments the test specification usually calls out explicitly.

Pre-Simulation Verification

Before committing compute time to the full run, verify the setup with a short settling simulation (a few milliseconds with gravity and belt tension active, no barrier). Check the following:

If the settling run shows belt elements snapping or the dummy drifting, do not proceed to the barrier run — the injury metrics will be meaningless. Fix the routing or the initial pre-tension first, then re-run the settling check.

Deliverable: Positioning and Routing Record

Fill this record from the model after the settling run passes. It is the artifact that lets a reviewer reproduce the occupant setup without re-deriving it.

Once this record is complete and the settling run is clean, the model is ready for the barrier run. Any later change to seat position, belt anchors, or dummy joints invalidates the record and requires a fresh settling check.