DRI_biom

Sourches:

DRI (Dynamic Response Index) 

It appears in NASA/TM-2002-211733 and NASA/TM-20030000682. 

Description: It calculates the chance of breaking the bones in your back when you are pushed hard from the bottom up. 

How it is calculated: Researchers imagine the human body is like a big spring. If you are pushed up too fast, the spring squishes. If the spring squishes too much or too quickly, it means the bones in the back could crack.

DRI_biom (Biomechanical Dynamic Response Index)

The DRI_biom (Biomechanical Dynamic Response Index) is a synthetic indicator designed to estimate the biomechanical stress experienced by the human body during an impact, with specific focus on spinal and dorsal loading, as typical in paragliding accidents.

DRI_biom does not represent a medical diagnosis and does not predict a specific injury.
Instead, it provides a comparative and quantitative measure of impact severity, taking into account both intensity and duration of the applied loads.

In simple terms:

DRI_biom tells you how “hard” and how “violently” the body is loaded during an impact, not just how high the peak acceleration is.

Simple explanation for the user

When a person hits the ground, the body is not damaged only by how high the acceleration peak is (for example 30 G), but also by:

• how fast the force builds up,

• how long the force acts,

• how concentrated the load is in time.
  
  

DRI_biom combines all these aspects into a single number.

• A short and sharp impact can be more dangerous than a longer but smoother one, even if the peak G is the same.

• DRI_biom captures this difference, while peak G alone cannot.
  
  

A higher DRI_biom value means a more severe biomechanical loading of the body.

Difference between DRI_biom and the official NASA DRI

Although the name is similar, DRI_biom is not the same as the official NASA DRI.

NASA DRI (official)

The NASA Dynamic Response Index was originally developed for:

• vertical seat ejection

• aircraft and spacecraft crash scenarios

• axial spinal loading of seated pilots
  
  

Key characteristics of NASA DRI:

• Based on a single-degree-of-freedom mass–spring–damper spinal model

• Tuned for military aviation environments

• Assumes vertical, axial loading

• Uses specific model constants fixed by NASA

• Outputs a value historically linked to injury probability in pilots
  
  

NASA DRI is model-specific and context-specific.

DRI_biom (this model)

DRI_biom is a biomechanically inspired adaptation, designed for:

• paragliding harness impacts

• back and dorsal protectors

• non-vertical, real-world impact profiles

• comparative evaluation of protectors
  
  

Key differences:

• DRI_biom does not assume a strict vertical impact

• It does not rely on a fixed anatomical spring–mass model

• It works directly on measured acceleration data

• It is signal-based, not anatomy-model-based

• It is intended as a relative severity index, not a medical injury predictor
  
  

In short:

NASA DRI is a physiological model.
DRI_biom is a biomechanical signal severity index.

What DRI_biom measures conceptually

DRI_biom measures the dynamic severity of an impact by combining:

• acceleration magnitude

• duration of loading

• temporal concentration of force
  
  

It penalizes:

• high accelerations,

• fast rise times,

• short and violent impulses.
  
  

It rewards:

• progressive deceleration,

• longer energy dissipation times.
  
  

How DRI_biom is calculated (textual description)

The calculation of DRI_biom follows these logical steps:

1. The acceleration signal measured during the impact is first filtered using a standardized low-pass filter to remove noise and sensor resonance.

2. An impact window is identified, corresponding to the first contact event where acceleration rises above a defined threshold and returns below it.

3. Within this impact window, the acceleration signal is normalized with respect to gravity, so that values are expressed in G.

4. The acceleration is then integrated over time, not to obtain displacement, but to evaluate the dynamic response intensity of the loading.

5. Higher accelerations contribute more strongly than lower ones, and shorter, sharper pulses are weighted more heavily than longer, smoother pulses.

6. The result is a single scalar value, called DRI_biom, representing the cumulative biomechanical severity of the impact.
   
   

The calculation intentionally mixes force intensity and time exposure, because biological tissues are sensitive to both.

Interpretation of DRI_biom values

DRI_biom is best used comparatively, not absolutely.

General interpretation:

• Low DRI_biom: smooth deceleration, good energy absorption

• Medium DRI_biom: noticeable biomechanical stress

• High DRI_biom: aggressive loading, increased injury risk
  
  

DRI_biom should always be interpreted together with:

• peak acceleration

• jerk

• absorbed energy

• residual equivalent force (REF)
  
  

No single parameter alone describes injury risk.

Important limitations

• DRI_biom is not a medical injury criterion

• It does not replace clinical assessment

• It does not predict specific fractures or lesions

• It is model-dependent and valid only within the defined test framework
  
  

Its strength lies in objective comparison and engineering evaluation, especially for protective equipment.

One-line summary

DRI_biom is a biomechanical severity index derived from measured acceleration data, designed to quantify how violently the human body is loaded during an impact, going beyond peak G and adapting the concept of DRI to paragliding-specific conditions.