Smart Airbag Design

The Smart Airbag project presents an innovative approach to airbag design, aimed at improving automotive safety by adapting to driver characteristics and crash dynamics. The research was conducted by me along with 3 other classmates from the Indian Institute of Technology, Madras, and focuses on minimizing the risks associated with airbag deployment, particularly for drivers seated closer to the steering wheel, such as shorter individuals.

KEY HIGHLIGHTS

PROBLEM IDENTIFICATION: Current airbags are designed based on the 50th percentile male, typically for drivers sitting 10–11 inches away from the steering wheel. However, many shorter drivers sit much closer, increasing the risk of head, neck, and facial injuries during airbag deployment.

PROPOSED SOLUTION: The Smart Airbag system aims to sense the driver's position and adapt airbag deployment accordingly. This includes controlling the airbag volume and pressure to ensure that it inflates optimally, reducing injury risks in the close-proximity scenarios.

DATA COLLECTION AND EXPERIMENTATION:

The team conducted experiments with four subjects, varying in height and weight, to analyze the relationship between seat distance, hip angle (H-angle), and pressure exerted on the airbag.
The study identified two key scenarios for airbag deployment: when the driver leans back (H-angle > 100 degrees) and when the driver leans forward (H-angle < 100 degrees).

The testing and measurement were done in Tata Manza. A pressure mat- was used for the pressure readings. Geometric readings were taken using a measuring tape, inclinometer, and a 30 cm scale.

The pressure mat is used to measure the base pressure (P) at the contact area (CA) with the seat as well as the Centre of Force (x,y) coordinates which helps in better analysis. We used the following formula to get the normalized pressure of all the test subjects to generalize the case: Normalized Pressure (NP)= (P X CA) / W where W is the weight of the person sitting or the test subject.

MATHEMATICAL MODELING:

A polynomial regression model was developed to predict the normalized pressure exerted on the airbag based on the driver's H-angle and seat distance. This model helps calculate the appropriate airbag volume and deployment force.
For real-time adjustments, sensors in the car's seat and steering system send data to the Electronic Control Unit (ECU), which then calculates the required airbag inflation.

Raw Pressure (P) and Normalized Pressure are inversely proportional to the H-angle and directly proportional to the seat distance.

ADVANCED AIRBAG INFLATOR DESIGN: The redesigned inflator features seven compartments, each with an initiator, allowing for selective activation based on driver size and collision severity. This design ensures a controlled and adaptive inflation pattern, preventing over- or under-inflation.

The compartmentalised inflation unit provides variable fluid volume, and we must adjust the airbag volume to ensure it fills up ideally and is not under or overfilled.

We have provided an additional steel rim enclosing the airbag and a compressible tunnel. The distance between the two can be varied depending on the occupant's position, thus varying the airbag volume.

SIMULATION AND VALIDATION: Using LS-DYNA, a simulation software, the team tested different nitrogen gas volumes (40L to 60L) to validate the model. The simulations showed that the system could protect drivers seated close to the steering wheel without excessive force.

RESULTS

The Smart Airbag system significantly improves driver safety by dynamically adjusting the airbag deployment based on real-time data. The experimental results showed 86.9% accuracy in predicting the steering to chest distance, validating the effectiveness of the system in minimizing proximity-related injuries.

Above is a dynamic simulation of the smart airbag system on the ANSYS LS Dyna Software

CONCLUSION

This project represents a breakthrough in airbag technology, combining mechanical, control, and chemical innovations. The Smart Airbag system's ability to adapt to driver characteristics and crash scenarios sets a new standard in automotive safety, offering a personalized and more effective safety mechanism for drivers of all sizes.

By addressing both human factors and technical limitations in current airbag systems, this project advances the field of automotive safety with a focus on saving lives and reducing injury risks.

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