Limits of Current Standards

Current equestrian helmet testing standards assess only linear impacts — that is, impacts perpendicular to the surface. In reality, however, accidents frequently involve oblique impacts, such as when a rider strikes the ground with a horizontal velocity component. Certimoov has incorporated this type of oblique impact into its testing protocols in order to better reflect real-world accident conditions.

To this day, the European standard still relies on an acceptance criterion based on acceleration measured using a rigid headform. This type of device does not accurately reproduce the behavior of the human brain and remains poorly representative of its true tolerance limits to impact. Certimoov, by contrast, uses a more advanced instrumented headform combined with a mathematical model of brain behavior developed from the analysis of several hundred real-world accidents. This approach enables biomechanical engineers and Certimoov to apply more realistic injury criteria, aligned with the brain’s actual tolerance to impact.

Finally, while current standards rely on a binary pass/fail acceptance criterion — a helmet is either compliant or non-compliant — Certimoov introduces greater nuance through a graded evaluation system, with scores ranging from 0 to 5.

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Brain Modeling and Mechanical Response Assessment

The Certimoov method relies on well-established engineering techniques similar to those used to calculate the deformation of a bridge or an aircraft wing. Applied to biomechanics, these techniques make it possible to model the human head and calculate the brain’s response during an impact.

To achieve this, a computer-assisted approach known as the finite element method is used. This method consists of dividing an object into a large number of small “elements,” each assigned precise mechanical properties, in order to accurately reproduce its behavior under different impact conditions.

In the brain model, these elements are assembled to reflect the gel-like properties of brain tissue. They make it possible to calculate internal stresses — in other words, the pressure and shear forces experienced by the brain during an impact.

This finite element model of the human head, developed by the ICube laboratory at the University of Strasbourg and known as the Strasbourg University Finite Element Head Model (SUFEHM), has been validated against numerous experimental studies published in the scientific literature. It provides a reliable foundation for studying and predicting the brain’s response to various impact scenarios.

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modele_cerveau_equestre

Simulation of Real-World Traumatic Brain Injuries

For more than 25 years, biomechanical engineers have collected data on traumatic brain injuries resulting from real-world accidents.

Detailed information about the circumstances of these accidents and the nature of the injuries has made it possible to reconstruct the victims’ trajectories and calculate the exact head impact conditions.

These analyses cover a wide range of individuals, including pedestrians, cyclists, motorcyclists, as well as athletes from various disciplines such as equestrian sports, skiing, and other high-risk activities.

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Simulation de traumatismes crâniens réels

Head injury tolerance limits

After collecting detailed information on impact conditions, biomechanical engineers were able to theoretically simulate more than 150 real-world traumatic brain injuries. These simulations made it possible to establish a relationship between the occurrence of coma and the internal stresses experienced by the brain during impact.

This work led to the definition of the brain’s tolerance limits to impact, known as injury criteria. Using these criteria in combination with data measured by the instrumented head surrogate, the device has become a true injury prediction tool, enabling the assessment and optimization of helmet protective performance.

It should be noted that the injuries considered in this approach are reversible in nature — namely severe concussions or short-duration loss of consciousness.

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Test and method

Horizontal anvil and
inclined anvil

The Certimoov testing method evaluates the shock absorption performance of helmets under conditions that closely replicate real-world accidents. The tests first include linear impacts, simulated by a vertical drop of a helmeted headform onto a flat horizontal surface (flat anvil).

Certimoov goes further by incorporating oblique impacts, simulated by a vertical drop of the helmeted headform onto a 45° inclined surface. This type of impact induces head rotation, a common phenomenon in real falls that is particularly important to consider for brain protection.

To provide a comprehensive and reliable assessment, each helmet model is subjected to six different types of impact (three on the flat anvil and three on the inclined anvil), each repeated three times, resulting in a total of 18 experimental tests:

Impacts on flat anvil:

  • Frontal

  • Lateral

  • Occipital

Impacts on inclined anvil:

  • XROT: Applied to the lateral area, inducing rotation around the anteroposterior axis (X-axis)

  • YROT: Applied to the frontal area, inducing rotation around the left–right axis (Y-axis)

  • ZROT: Applied to the lateral area, inducing rotation around the vertical axis (Z-axis)

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Enclume horizontale et enclume inclinée

Illustration of the 6 impact conditions
(3 linear and 3 oblique)

Improved headform with
linear
and rotary accelerometers

The headform used by Certimoov enables more precise and realistic testing. The headforms currently used in standard regulatory tests are not fully suited to the new types of impacts considered by the Certimoov method.

Today, headforms used in regulatory tests have several limitations:

  • Rotational inertia is not adapted to the impacts being tested

  • Head-to-helmet friction is unrealistic

  • Measurements of head rotation are incomplete or limited according to current standards

To overcome these limitations, Certimoov uses an instrumented Hybrid III (HIII) headform. This head model allows impacts to be reproduced more realistically and enables precise analysis of what happens at the moment of impact.

Thanks to integrated sensors, all head movements are recorded over time: not only the accelerations related to translational motion, but also the speed at which the head rotates during the impact. This data provides a comprehensive view of helmet performance and the level of brain protection it offers during an impact.

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têtes ISO utilisée dans les normes actuelles

The ISO head used in current standards and the mannequin head used by Certimoov

Theoretical answer of
brain to a real shock

Certimoov’s major innovation lies in combining physical testing with a digital tool capable of estimating the risk of neurological injury.

Specifically, head movements measured during an impact — including both linear accelerations and rotations — are fed into a digital brain model. This model allows the stresses experienced by brain tissue at the moment of impact to be analyzed.

Using this data, Certimoov evaluates the intensity of the stresses on the brain and translates them into an injury risk level using a scientifically validated risk curve. This approach goes beyond simple impact measurements: it provides insight into what the brain actually experiences during a collision and allows a more accurate assessment of the protection offered by each helmet.

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Illustration de la méthode couplée « expérimentale et numérique »

Illustration of the coupled “experimental and numerical” method which makes it possible to assess the risk of injury for a given shock.

Read more

Reading the note

Calculation of an average
risk level of suffering a moderate
neurological injury

To ensure reliable results, each type of impact is repeated three times. In total, a single helmet model is subjected to 18 different impacts. Conducting all these tests requires six identical helmets per model, in order to perform tests on both the flat and inclined anvils.

Repeating the impacts ensures consistent, reliable results that accurately reflect the helmet’s real-world protective performance.

For each impact, a numerical simulation analyzes the stresses experienced by the brain. The results are then compiled and represented on a risk curve to determine an overall injury risk level, taking into account all tested scenarios.

The helmet’s final score is calculated based on this overall risk: the lower the injury risk, the higher the score. This provides a simple and transparent way to compare different helmet models.

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Calcul d’un niveau de risque moyen de subir une lésion neurologique modérée

Method for assigning scores based on the risk of injury obtained overall for the 18 impacts

Inform the consumer
about the comparative level of protection
offered by
different helmets

Because safety must be the first criterion when choosing a helmet, Certimoov allows users to find more details on the level of brain protection provided by the helmet. The headsets tested receive a rating between 0 and 5, with 0 being the lowest rating and 5 the best. It is essential to remember that all approved helmets protect satisfactorily. If some obtain a low rating it is because they have not been manufactured (optimized) to protect against oblique impact but also because the level of injury taken into consideration in Certimoove is a reversible injury. The objective is to identify the best and develop them.

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