Noise for electric vehicles and hybrid electric cars

Given its reputation for racing and road performance going cars that are anything but quiet, it should come as no surprise that, Lotus Engineering, the design and technology division of one of the most famous car brands in the world, is working on making silent electric cars louder and, in doing so, to save lives.

With more and more electric and hybrid cars with lithium ion batteries on the roads, there is clear evidence that these silent electric cars put pedestrians at risk as there is no audible warning of their approach and governments around the world are preparing legislation to make these silent cars produce noise to warn pedestrians of their presence.

But to have a car that simply made noise all the time means additional – and unnecessary for most of the time – noise pollution. So Lotus and HARMAN have created an intelligent pedestrian warning system integrating the advanced HALOsonic sound synthesis system with video technology that spots pedestrians as the car approaches and sends noise in their direction at suitable volume to warn them of the car’s approach. The system will even allow the driver to choose the noise their car emits, from reproductions of conventional car engines, through music to science fiction sounds!

The system has been built into the Lotus Evora hybrid demonstration car and will have an obvious role in the Lotus City Car, an electric urban car set to be part of the new car of Lotus cars to be launched in coming years.

This cutting-edge enhanced version of the HALOsonic safety system incorporates input from imaging sensors to enhance the quality of the sound synthesis system. HALOsonic has been developed specifically for electric vehicles and hybrid electric vehicles

The system on this latest version of HALOsonic, a collaboration between HARMAN and Lotus uses a single camera to determine the distance, trajectory and speed of pedestrians and other road users, calculating the risk of collision by comparing this information with the car’s path. The new HALOsonic system uses this data to actively control the volume of the External Sound Synthesis to warn pedestrians of the vehicle’s location, thereby improving pedestrian safety and reducing noise pollution.

Under certain conditions the system will generate an audible and visual warning for the driver using the Internal Sound Synthesis and instrument panel.

The new active system is optimised to operate in urban environments where there is the greatest risk of a collision with a pedestrian. It is calibrated to actively control the volume and pitch of the sound synthesised while the vehicle is travelling from 0 – 75 km/h, continually evaluating the risk of a pedestrian collision and operating in an area up to 60 metres ahead of the vehicle. All of the HALOsonic systems are designed to use low levels of power and with the new active version there will be less power consumed as the system will only increase the volume when there is a risk of an impact.

This innovative new active safety system is integrated into the HALOsonic range of products, which includes: External Sound Synthesis, Internal Sound Synthesis, Road Noise Cancellation and Engine Order Cancellation. The HALOsonic range has been designed by Lotus Engineering and HARMAN Automotive and offers a production ready technology as a stand-alone or integrated ICE system solution.

Governments around the world have acknowledged the increased risk posed by almost silent vehicles and are in the process of drawing up legislation to compel car manufacturers to equip vehicles with pedestrian warning systems like the HALOsonic system.

Colin Peachey, Chief Engineer, Control and Electrical, Lotus Engineering said, “The integration of video technology into the HALOsonic system illustrates the flexibility of the technology to evolve new features and functionality; offering a system that is more intelligent and produces less unwanted noise while using less power! This is just one of the several enhanced functions we are currently developing for HALOsonic that is now the global benchmark pedestrian safety system of this type, and which is receiving a lot of attention from large vehicle manufactures keen to meet the upcoming legislation in the US and Japan. The HALOsonic system offers the ability to tune the sound synthesis to a manufacturer’s requirements, giving the capability to synthesise anything from a conventional engine sound to a very futuristic Sci-Fi designer sound.”

Lotus Engineering provides comprehensive and versatile consultancy services to many of the world’s car makers and component suppliers and is an internationally recognised automotive engineering consultancy. Global facilities include those in the US, Malaysia, China and offices in Germany and Japan. Lotus is a global high-tech company, expanding rapidly and committed to driving forward technology for both Lotus Cars and its Engineering clients, spearheading research into such areas as hybrids, electric vehicles and renewable fuels.