14 Platform one ABLIC has developed an analogue power system that can detect faults in autonomous vehicles 20 times faster than digital devices, writes Nick Flaherty. These high-speed voltage regulators are key to the safety of autonomous vehicles, but creating entirely errorfree, malfunction-proof systems is increasingly challenging. If the steer-by-wire fails during autonomous operation, there is a risk of losing vehicle control and an increased likelihood of lane departure. To mitigate this, the system switches to a subsystem that provides minimal steering assistance before transitioning to manual operation. However, even after control is transferred to the driver, the loss of power assistance significantly impairs operability, making it crucial to have robust fail-safe mechanisms in place. Similarly, a failure in the battery management system (BMS) can necessitate an emergency stop, potentially causing high-speed collisions, especially with following vehicles. A multi-tiered approach is essential to address the challenges of functional safety in autonomous vehicles. This strategy emphasises the importance of systems transitioning to a safe state when encountering unexpected situations. For example, electronic steering should switch to a subsystem, providing minimal steering assistance through a safety mechanism before transitioning to manual. Similarly, the BMS should have a backup power supply to maintain critical functionalities. This layered approach provides redundancy, ensuring multiple safety mechanisms are in place to prevent or mitigate potential accidents. Transitioning to a safe state is a crucial process and involves three anomalies significantly faster than digital devices. Operating up to 20 times faster, they contribute to meeting FTTI requirements. This improvement allows for more time in fault handling, enabling complex safety mechanisms. For example, ABLIC’s S-19990/9 series of automotive, analogue, step-up switching-regulator controllers can be used for backup power for electronic control units (ECUs). While most ECUs operate using 12 V auxiliary batteries as their main power supply, if a vehicle is subject to a severe impact, such as in a traffic accident or collision, and power is lost, the S-19990/9 series will stop operating. Backup power supplies can be installed for the ECU in, for example, electric door latches and emergency communication systems to maintain operation for a set period of time, even after an accident. These backup supplies are generally composed of capacitors/batteries and a step-up circuit. When they use lowvoltage capacitors/batteries to achieve downsizing and lower costs, a stepup circuit is required to boost this low voltage to 12 V of backup power. Safety key steps: detection, notification and handling. The time to complete these steps is critical and is regulated by the Fault Tolerant Time Interval (FTTI), as specified in ISO 26262. Detection involves identifying anomalies within the system. Notification is the process of communicating the detected anomaly to the relevant parts of the system responsible for managing faults. Handling is the final step, where the system takes action to mitigate the detected issue. This could involve activating backup systems, adjusting operational parameters or initiating a safe shutdown procedure. Optimising detection and notification can significantly enhance overall system safety. By doing this, particularly with detection and notification, autonomous vehicle systems can have more time for appropriate fault handling. This could allow for the implementation of more sophisticated safety mechanisms or enable new handling methods to enhance vehicle safety. Analogue voltage-monitoring integrated circuits detect and notify February/March 2025 | Uncrewed Systems Technology Detecting faults in autonomous vehicles 20 times faster Analogue voltage regulators for autonomous safety (Image courtesy of ABLIC)
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