AVAS, the voice of electric vehicles for pedestrian safety

AVAS, the voice of electric vehicles for pedestrian safety

The Acoustic Vehicle Alerting System (AVAS) was introduced as the number of low-noise vehicles such as electric vehicles increased. This is a minimum safety device to prevent an accident due to pedestrians not noticing the approach of a low-noise car with low operating noise. It's also ironic when you consider that vehicles with internal combustion engines work hard to reduce engine noise. South Korea has legalized the installation of warning sound generators in low-noise vehicles by Ordinance of the Ministry of Land, Infrastructure and Transport.

HL Clemove started full-scale AVAS development at the point ahead of the enactment of the mandatory AVAS installation regulations. HL Clemove's virtual engine sound system has been developed and mass-produced for the 3.5th generation since the first generation product development. We have R&D capabilities to cover all areas required for AVAS development, such as system engineering, software programming and development, and HW design. 

HL Clemove has contracts to supply 1st-generation AVAS products to MAN, SCANIA, MFTBC, etc., and has signed AVAS supply contracts for 23 models of HKMC (Hyundai/Kia), including Ioniq 5, and is in the process of mass production and development. . In addition, we are increasing our share in the AVAS market by signing supply contracts with leading companies around the world. It is expected to supply more than 3 million units in 2026. 

Finding an AVAS that satisfies the laws and customer needs 

It is important for AVAS to produce performance that meets the standards set by the law. There are many standards to be followed, such as the situation where the warning sound is output, the volume of the warning sound, and the change of the warning sound according to the speed change. Briefly, a warning sound must be emitted when driving at least 20 km/h or less, and the frequency range within the range of 160 Hz to 5 kHz must be observed. 

HL Clemove provides AVAS with the ability to adjust the size and frequency of virtual sound through vehicle speed and gear information, and to output and tune the sound using sound algorithms so that low-noise vehicles can satisfy the law. When the sound source delivered from the customer is applied to the product, a legal test is conducted in an anechoic chamber to ensure compliance with the regulation, and a sound tuning tool is used to check whether the regulation is satisfied. AVAS legal test progress in an anechoic chamber.

When designing AVAS, HL Clemove focuses on function and quality of sound. Since the virtual engine sound is directly heard by people passing near the vehicle, much effort is being put into developing the sound algorithm to prevent noise or abnormal noise from occurring when the engine sound is output. 

In fact, HL Clemove has gone through a lot of processes from the development of the 1st generation AVAS to the development and mass production of the 3.5th generation. At the time of the development of the first generation AVAS, we came up with the concept of HL Clemove's own AVAS product while thinking about how to make sound and what functions should be added to implement AVAS that meets the customer's needs. In this process, we collaborated with a sound specialist for high-quality sound, and worked closely with experts called ‘Golden Ears’ to determine if there were any abnormalities in the sound and to check the sound for each band. 

Since then, from the second generation products, internalized sound algorithms have been applied. In the 2nd generation AVAS, the frequency modulation and volume control algorithms required for virtual engine sounds are applied, and from the 3rd generation of AVAS, the existing algorithm is improved and mixing and EQ filter functions implemented by controlling multiple sounds are added to the algorithm. It has gone through advanced stages such as system function improvement and support program development. 

From AVAS 3.5 generation, HSM requirements for cyber security response were applied, and backup memory requirements for existing software backup were additionally applied when responding to OTA. In addition, it is designed to enable individual control of all parameters for each sound, increasing the degree of freedom in sound tuning. Currently, we are working to improve software quality based on the A-SPICE process. 

AVAS is basically a ‘mouth of the car’ that outputs sound to the outside of the vehicle through speakers. Through AVAS, HL Clemove made it possible to directly deliver the vehicle's condition not only to pedestrians passing by the vehicle, but also to the driver outside the vehicle. This is the addition of an event sound output function that audibly informs the charging status by outputting a separate sound when the vehicle's charging plug is attached or released. HL Clemove is carefully examining the possibility of expansion for various sound notifications, such as anti-theft notification sound, door lock/open sound, and charging reservation notification sound, based on customer requirements. 

However, introduction of these various functions or changes to the system should basically be done within the standards set by the law. This is because AVAS is basically a product for legal compliance. For example, the current law prohibits changing the certified sound, so it is impossible to customize the warning sound to the sound desired by the borrower or control the volume arbitrarily.