Study On The Design Of External Sound For Low-speed Electric Vehicles At Urban Traffic Junctions

In the face of severe energy crisis and deteriorating environmental problems,low-carbon economy has become the main development direction in the future.Electric vehicle owns excellent properties such as green and low-carbon,but their near-silent characteristics when driving at low speeds make it difficult for pedestriants especially those visually impaired,the elderly,children to recognize the approach of the car,which may increase the risk of traffic accidents.At present,the governments of the United States,Japan,Europe and other countries have issued regulations that require electric vehicles driving at low speeds to make appropriate external sound.China also requires electric vehicles to make appropriate external sound to pedestriants when driving at low speeds(below 20km/h).According to the dilemma of the electric vehicle external sound at low speed,considering both safety and quietness,the research goal of this paper is to develop an efficient virtual reality experimental system through the related research on the external sound,to discover the external sound with both sufficient information and satisfactory,as well as promote the design principles of external sounds at the sound tone perspective.This paper first research in the current situation of electric vehicle external sound application and sound quality evaluation method,which will help to build the virtual reality experimental system the develop the foudamantal external sounds.With surveys and interviews,the specific situations and existing problems of electric vehicles driving at low speeds could be well learnt,conducting comparative studies on pedestrian interaction behaviors when come across electric vehicles at low speed conditions.According to the modes and types of external sounds and the characteristics of pedestrians’ perception of the sound quality,a sound design method based on pedestrian needs is proposed.Based on the scenario of the electric vehicle external sound,a set of external sound virtual reality experimental evaluation system was designed.The sound in the low-speed driving scene of the electric vehicle is simulated through 3D virtual reality technology to create an immersive sound experience environment for pedestrians of different ages.The result of the experiment suggested that the concise and clear signal tones were founded by most pedestrians while electric vehicles owners perfered sounds similar to car;however,external sounds in natural tone performed poorly in experiments.The experiments were operated with virtual reality technology,which could take both effectiveness and safety into account;and divided into two dimensions: electric vehicles owners and pedestrians,which revealed an overall consideration and made the results of the experiment more reliable.The research results have positive value for promoting the design and research of low-speed electric vehicle external sounds and the formulation of related standards.It can provide timbre types and characteristics for vehicle OEMs and suppliers when designing lowspeed electric vehicle external sounds,and enrich the external sound evaluation aspects.