While the airbag is essential for occupant protection, is it also an obstacle to visualizing the distance between the dummy head and rigid objects on the car or other occupants. During the restraint system development process, it is important to understand where the dummy head is in order to modify the restraint systems and avoid bottoming out.

Photogrammetry and motion analysis combined with 3D software enables the minimum distance between the 3D scanned dummy head and any other 3D surface to be calculated. Using the videos from the high-speed cameras the 3D position of any visible point can be obtained. As the head is a rigid object, it is possible to determine where the entire head is relative to the steering wheel with just the position of any point on the back.

With the arrival of 3D high-resolution scanners, HD high-speed cameras and new tracking algorithms, the results obtained from this methodology have increased in precision up to the millimetre scale. This methodology shows the behaviour of a rigid object during a crash or sled test in a 3D environment and can be used as a strong tool in passive safety laboratories. In this particular case, displacement and rotations of the head dummy relative to the car coordinate system determine if the head is too close to the dashboard, “B” pillar, steering wheel, etc.

This methodology requires two high-speed cameras. During a passive safety development process, it is essential to have all high-speed cameras available to monitor critical parts of the car. To reduce the number of cameras required to calculate the behaviour of the head relative to the car, the 6DoF tracking method can be used. This method uses the static position of a group of points in a rigid object to calculate the 3D rotation and displacement of the centre coordinate system. There are some difficulties that limit this process, which will be dealt with here.

This methodology is not commonly applied in every test, usually because the two cameras and the digital process required increase the cost of the crash or sled test. Reducing the number of cameras needed to only one can reduce the cost of this methodology and its implementation for all related tests. Also, there is the possibility of calculating this methodology by using on-board cameras, which is very helpful when the car deploys the curtain airbag.

With the coming of the autonomous car, the Passive Safety Department must have all measurement tools available to understand how dummies behave inside new car morphologies. This tracking methodology could us help to understand how dummies interact with rigid parts of the car in order to modify the restraint systems so as to be adapted to new technologies.