Ams introduces capacitive sensors that meet automotive grade certification

Ams Semiconductor, the world's leading provider of high-performance sensor solutions, has introduced an automotive-grade certified capacitive sensor, the AS8579, that enhances the safety of automated driving assistance systems. The AS8579 performs manual driving detection at the steering wheel rather than on the steering lever, making it more reliable and economical. By introducing the AS8579 capacitive sensor

The AS8579 uses a new capacitive sensing technology that performs a separation of the resistance and capacitance portions (quantity/share/proportion) based on the impedance measured by the sensor element. Compared to the capacitance-sensing charge and discharge methods used in today's cars, this technology can more reliably detect whether the driver has both hands on the steering wheel - even when wearing gloves or in wet conditions. This means that the AS8579 helps automakers improve the safety of advanced driver assistance systems (ADAS) while reducing the cost of manual driving detection systems: The AS8579 can sense the impedance of steering wheel heater elements, while similar capacitive sensing systems for manual driving detection require dedicated metal sensor elements built into the steering wheel.

Alexander Rensink, Position Sensors Business Unit Manager at AMS, said: "The more sophisticated capabilities of ADAS, as well as the full or partial autonomous driving systems of the future, will bring significant benefits to car users and society as a whole, such as reducing traffic congestion, reducing the number of accidents caused by driver fault, and making the road more pleasant. "ADAS is designed to keep vehicles and people safe, and by introducing the first fraud-proof manual driver detection system for all driving conditions, AMS is making a significant contribution to the safety of the next generation of ADAS-equipped vehicles."

Improved AMS capacitive sensing technology addresses concerns about the safety of ADAS

Developing a reliable way to detect if a driver's hands are on the wheel could remove an important barrier to the large-scale deployment of ADAS in passenger and commercial vehicles. Automakers are implementing increasingly sophisticated autonomous driving features, including features such as adaptive cruise control, traffic jam start-stop systems, and LKAS. All of these features require the driver to be ready at all times to take back control of the vehicle immediately if the vehicle's systems fail to detect a security threat, and manual driving detection is a critical part of all systems used to monitor driver readiness.

Torque sensors have been used in the past to detect continuous, tiny deflections when the driver holds the steering wheel, but this form of manual driving detection can be easily fooled (illegally), posing risks to the driver and other road users.Now, the trend in the automotive industry is to use capacitive sensing for manual driving detection, as this technology is more reliable for human contact, simpler to design and build, and less costly than other options.

The charge and discharge method of capacitive sensing is easy to understand, and this technology has been used for years in products such as touch screens and touch-sensitive buttons. However, detection fails when the driver is wearing gloves, and moisture or moisture can also produce false detection signals, undermining the safety performance of manual driving detection based on this capacitive sensing method. By implementing reliable capacitive sensing based on I/Q demodulation, AMS 'AS8579 capacitive sensor enables automotive manufacturers to achieve extremely high safety standards in more complex autonomous driving and driver assistance functions that are still being developed today.

The AS8579's security credentials also include the provision of multiple on-chip diagnostics, ensuring support for the ISO 26262 functional safety standard up to ASIL Level B. Sensors comply with AEC-Q100 Level 1 certification. The AS8579 operates at four selectable driver output frequencies (45.45kHz, 71.43kHz, 100kHz or 125kHz), providing excellent resistance to electromagnetic interference.