Seat Position Hard Points

When we design custom seat brackets, we do not start from experience and estimates alone. We first describe the car, the seat and every driver as one digital model, made of named 3D reference points: hard points. Each hard point has an exact X, Y and Z position. Together they form a parametric skeleton of the driver, seated in the car, that we can check, adjust and export straight into our CAD software.

The calculations are geometric and reproducible. Image analysis helps us collect body measurements, but it never replaces the calculated model: what you see in the viewer, the hard point table and the final CAD file all come from the same geometry.

The coordinate system

Every project uses one consistent, right-handed coordinate system that is fixed to the vehicle.

Origin

Defined in the vehicle baseline and identical for every driver and every export

X

Positive towards the front of the car

Y

Positive towards the left of the car

Z

Positive upwards

Unit

Millimetres

A hard point's name combines the driver and the anatomical point, for example DRV01_L_HIP, DRV01_R_KNEE or DRV01_EYE_CENTER. Vehicle points start with VEH. The exact coordinates go from the calculation model into the CAD geometry without any separate rounding.

Driver hard points

These are the points of the anatomical skeleton. They are adjusted to each driver from body measurements, photo analysis or anthropometric data.

Vehicle hard points

These points describe the car: where the seat is mounted, where the steering wheel sits and how the pedals move.

The reference position

Every configuration is checked in a fixed starting position:

• Pelvis and H-point at the chosen seat position.

• Back and shoulders following the backrest.

• Right foot on the throttle, with the pedal fully pressed.

• Left foot on the footrest or near the brake, without pressing it.

• Both hands on the steering wheel, at roughly nine and three o'clock.

• Head and eyes in a plausible driving position, with the line of sight towards the windscreen and the road.

Full throttle is a mandatory check. We also look at:

• Brake pedal fully pressed

• Steering wheel turned left and right

• Seat at its most forward and most rearward setting

• Clutch pedal fully pressed, if the car has one

What we check

• Hip, knee and ankle angles

• Shoulder and elbow angles

• Reach to the steering wheel and the pedals

• H-point position, seat base angle and backrest angle

• Head and helmet clearance

• Line of sight and field of view

• Room around the knees and legs

• Collisions between driver, seat and car

• The seat adjustment that is available, and the adjustment that is needed

We only accept configurations that are geometrically plausible. If not every requirement can be met at the same time, we say so instead of forcing an unrealistic skeleton into the car.

Where the measurements come from

Car and seat

We use the most reliable source available, in this order:

1. Our own verified 3D scan or STEP model

2. Checked manufacturer CAD or technical drawings

3. Checked manual measurements

4. Information found online that has not yet been verified

5. Geometry estimated from known dimensions

The driver

1. Checked individual body measurements

2. Calibrated photo analysis combined with body measurements

3. Photo analysis combined with statistical models

4. A statistical dataset without an individual photo

Without a photo, we use a statistical body model from a documented anthropometric dataset, such as DINED from TU Delft. We record the source, population, year and margin of uncertainty, and we never assume that everyone from one country has the same proportions.

Data quality

Every value carries a status, which stays visible in the viewer, the reports and the exports:

Verified

Checked scan, CAD data or a reliable manual measurement

Manufacturer data

Manufacturer information whose origin and model version are known

Calculated

Derived numerically from other values and assumptions

Estimated

Estimated from photo analysis, population data or incomplete sources

Missing

Required data that is not available yet

Photos for your body measurements

If you would like us to estimate a driver's proportions from photos, this is what works best.

1. Full body, side view

   • Stand upright in a natural posture, with your whole body in the picture, head and feet included.

   • Take the photo exactly from the side, with your arms slightly away from your body so the joints are visible.

   • Wear close-fitting clothes, no thick jacket, and no shoes or heels.

   • Use a plain background if you can, and hold the camera at about hip height, without tilting it.

   • Avoid wide-angle distortion, and tell us your actual height.

2. Full body, front view (recommended)

   • Stand upright, facing the camera, with arms and legs clearly visible.

   • Use the same camera distance and settings as for the side view.

3. Calibration (recommended)

   A measuring stick or another object of known size, in the same plane as the person, helps us check the scale of the image.

One photo cannot capture every real 3D dimension exactly. We check the quality of the photos first and ask for extra photos or measurements when something is uncertain.

More than one driver

A car can have any number of drivers. Each driver gets their own skeleton and position, and we compare them to find:

• The most forward and most rearward seat position needed

• The lowest and highest usable seat height

• The adjustment range needed in X and Z

• Differences in backrest and seat base angle

• Critical knee and head clearance

• Whether one adjustable mounting solution fits every driver

We never assume that the shortest driver needs the most forward position or the tallest the most rearward one: leg length, arm reach and torso length are each taken into account. If no common solution exists, we show which requirements conflict.

What you receive

STEP

For Autodesk Inventor: hard points as spheres, connections as cylinders, seat contours and references as CAD geometry

STL

For visual checks and meshes

CSV / Excel

The complete hard point table with names and XYZ coordinates in millimetres

JSON

The full configuration: inputs, transformations, constraints, data status and revision

PDF

Your approval, the key dimensions, starting points, warnings and screenshots

Approval and responsibility

Before anything is exported, you review the proposed configuration and confirm each point separately: the vehicle, the seat, the drivers and their measurements, any estimated data, the seating preference, the pedal and steering positions, the adjustment range and the available space. We record who approved what and when, together with the exact values and sources used. If anything changes afterwards, the approval lapses and a new revision is needed.

Questions