## 4 Design of Sound Simulation System and Validation of Motion Sensing Target
### Validation of Motion Sensing Sound Targets  
The function of the sound simulation system is to simulate the engine sound with motion sense auditory feeling when the pure electric vehicle is accelerating. It is a simulation of sound dynamics to achieve driver interaction with vehicle acceleration behavior.  
According to the hardware selection and the connection relationship of each module, the hardware system of sound simulation is constructed. Firstly, the written software generates C code in LabVIEW, and then calls Keil uVision to jointly compile it into an executable file, and finally downloads it to the main control chip of the hardware through the JATAG simulator.  
First, the USBCAN-II device, vehicle loudspeaker, computer, and other hardware are connected to the sound simulation system, and then CAN is used to send the host computer to send vehicle driving data packets to the sound simulation system. Finally, the accelerated sound is actively simulated by the loudspeaker after the main control chip is calculated. Call the computer sound card correlation function using LabVIEW. The simulated accelerated sound acquisition is recorded and saved in the form of wav file and compared with the input sound source of motion sense characteristics designed to determine the function realization of debugging sound simulation system design. Figure 23 shows the test platform of accelerated motion sense sound simulation system.  
Figure 23: Test platform of accelerated motion sensing sound simulation system.  
Figure 22: Connection relationship of the test platform of a sound simulation system.  
The sound synthesis of the accelerator pedal is simulated in the three intervals of 0-30%, 30-60%, and 60-90%. The sound pressure level in the car can be adjusted by the gain of the power amplifier during acceleration. Figure 24 shows the pedal opening signal changes under different acceleration conditions.  
The collected wav files were imported into LMS Test Lab for time-frequency analysis. Figure 25 shows the time domain diagram of synthesized sound signals under the change of pedal aperture of 0-30%, 30-60%, and 60-90%, respectively.  
As can be seen from Figures 25 and 26, when the sound simulation system is working, the synthesized sound under different pedal aperture can dynamically adapt to the change of vehicle state. With the increase of accelerator pedal aperture, the amplitude of synthesized sound gradually increases, and the frequency distribution of sound energy gradually increases, and the order harmonic distribution is basically consistent with the characteristics of the designed motion sensing sound source. With pure odd order harmonics as the main sound components, the motion sense order characteristics of the simulated synthesized sound are verified. The synthetic sounds above add to the driving experience.  
Figure 24: Cont.  
Figure 24: Pedal aperture signal changes under different acceleration conditions. (**a**) Accelerator pedal aperture 0–30%. (**b**) Accelerator pedal aperture 30–60%. (**c**) Accelerator pedal aperture 60–90%.  
Figure 25: Synthesized sound signals under different accelerator pedal aperture changes.