Smart Seatbelt Technology

For the better part of the 21st century, automotive safety systems have seen considerable advancement and innovation in airbags, driver-assistance functions, and vehicle stabilization mechanisms. Seatbelts have not progressed much outside of the new smart cameras installed at traffic lights and other intersections to check if drivers and passengers are buckling up in compliance. Thanks to reputable engineering firms such as ZF Friedrichshafen, seatbelts are getting a smart technology update that is expected to hit the automaker parts market in 2025.

In early 2024, the Passive Safety Systems division of ZF Friedrichshafen announced the release of a new automotive safety restraint system that features a new smart technology called a Multi-Stage Load Limiter (MSLL), which adapts to the shape, size, and height of drivers and passengers. This is the first seatbelt system that can accurately be described as a smart technology; the MSLL turns seatbelts into flexible components that can be controlled and automated through telematics.

With MSLL technology, the efficiency of seatbelts is enhanced to meet the Eurozone New Car Assessment Programme, which is currently evaluating solutions for the NCAP Vision 2030 plan for a safer automotive future. The new crash testing guidelines under NCAP demand better protection for all vehicle occupants, and the engineers at ZF Passive Safety Systems are focusing on the early stages of road traffic accidents involving collisions.

How MSLL Technology Improves Seatbelt Functionality

In modern car safety systems, seatbelts jump into action before the impact stage of a crash happens. When a collision is imminent, seatbelts tighten up through pre-tensioning to take without any slack. This action keeps drivers and passengers from jerking forward too much. After the impact, the belts slow down the forward force gradually before making contact with airbags in mid-deployment. This is a two-stage controllable load limiter mechanism, which the automotive industry abbreviates as SLL.

With the MSLL technology developed by ZF Passive Safety Systems, SLL is improved from a two-stage mechanism to one that acts upon the variability in belt forces. In the future, seatbelts will be even smarter thanks to MSLL systems that will use sensors inside the car to measure the mass and height of vehicle occupants; this will determine how the seatbelts should be adjusted when the car is moving, when the risk of collision is higher, and in the milliseconds before and after impact.

The Future of Seatbelts and Automotive Safety

MSLL opens the door to improved automotive safety beyond its core pre-tensioning and tension-control mechanism. As previously mentioned, MSLL technology is smart in the sense that it can communicate with other systems. With the Mercedes-Benz Driving Assistance Package, for example, MSSL can pre-tension the seatbelt based on data collected by the pre-collision, lane departure, or blind-spot monitoring sensors.

MSLL can also work with airbags. After recording the size and position of occupants through interior sensors, MSLL can adjust belt force according to the speed and force of the airbag, thus optimizing protection for everyone in the car.

The global market for automotive safety restraint systems is projected to rise to a $36.8 value by the time the NCAP Vision 2030 plan is implemented through new rules and regulations. The ZF Group will continue its research and development efforts beyond MSLL to come up with even more advanced safety solutions; in the meantime, the Passive Safety Division will collaborate with other firms in the automotive industry to expand the integration of new technologies.

Seatbelts can be the difference between life and death in a catastrophic collision. With tens of thousands of deaths each year, 99 in Oklahoma City alone in 2021, advancements in seatbelt technologies could potentially save thousands of lives each year.