# A Review of Seatbelt Technologies and Their Role in Vehicle Safety
## 3 Results
### Interconnection of Active and Passive Safety Systems
In the context of autonomous vehicles, smart seatbelt systems evolve further by interacting with the vehicle's high-level perception and planning modules. For instance, Waymo's self-driving vehicles incorporate predictive algorithms that assess surrounding traffic patterns and pedestrian behavior, allowing the vehicle to anticipate complex scenarios. If a rapid deceleration or evasive maneuver is likely, the seatbelt system can dynamically  
Figure 12: A 3-point seatbelt system with a pre-pretensioner and retractor mechanism. adjust tension to prepare for abrupt movement, even before traditional crash sensors are triggered. Moreover, in vehicles equipped with occupant recognition technologies--like Tesla's cabin camera system [41]--smart seatbelt mechanisms can adapt restraint force or enable features like child-specific protection modes based on who is seated and how they are positioned. These intelligent systems mark a shift toward personalized, context-aware occupant protection in both semi-autonomous and fully autonomous mobility platforms. Another advancement is the development of automatic and reversible seatbelt pre-pretensioning mechanisms. These systems can retract the seatbelt sharp by up to 300 mm within milliseconds, providing immediate restraint tightening in response to emergency scenarios. Such rapid pretensioning enhances occupant positioning and minimizes forward movement before a crash occurs [42]. Further refinement of active safety technology includes pre-safe seatbelt systems that ensure continuous and firm contact between the occupant and the restraint system. By preemptively tightening the seatbelt in critical situations, these systems enhance stability and optimize the interaction between occupants and supplementary passive safety devices, such as airbags, to mitigate injury severity [43]. The convergence of active and passive safety technologies represents a paradigm shift in automotive safety, transitioning from purely reactive protection to anticipatory and adaptive restraint mechanisms. These advancements underscore the increasing role of intelligent safety systems in reducing injury risk and improving crash survivability. Active safety systems, such as AEB and lane departure warning systems, are increasingly integrated with passive safety systems. This interconnection allows for a more effective response to danger. AEB systems can activate the pre-pretension of the seatbelt before impact, preparing the occupant for a collision. Lane departure warning systems can also activate the belt pre-pretensioner in the event of an unintentional deviation. Information on the interaction between active and passive safety systems can generally be found in the automotive safety literature, although the specific documents provided do not detail these aspects. The paper by [44] presents a simulation methodology combining PreScan ([[https://www.sw.siemens.com/en-US/services/engineering-consulting/simcenter/testing-facilities/](https://www.sw.siemens.com/en-US/services/engineering-consulting/simcenter/testing-facilities/)]([https://www.sw.siemens.com/en-US/services/engineering-consulting/simcenter/testing-facilities/](https://www.sw.siemens.com/en-US/services/engineering-consulting/simcenter/testing-facilities/)), accessed on 5 May 2025) and Madymo ([[https://plm.sw.siemens.com/en-US/simcenter/mechanical-simulation/madymo/](https://plm.sw.siemens.com/en-US/simcenter/mechanical-simulation/madymo/)]([https://plm.sw.siemens.com/en-US/simcenter/mechanical-simulation/madymo/](https://plm.sw.siemens.com/en-US/simcenter/mechanical-simulation/madymo/)), accessed on 5 May 2025) software to develop integrated safety systems. The focus is on side impact collisions, aiming to enhance occupant protection through coordinated system behavior. Coupled simulations model both vehicle dynamics and human biomechanics during impacts. Results show improved system performance via integration of active and passive safety features. Also, the study by [45] explores the synergy between vehicle dynamics data and passive safety mechanisms.