RNC controller hardware design
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Hardware design and IC selection need to consider the following key points:
- The computing power and storage capacity of the main chip IC
- Number of audio channels and audio stream path
- Control and troubleshooting
- System delay
- Heat dissipation efficiency
- Whether built-in sound algorithm
- Installation size
- total cost
RNC controller software design
Development of MCU and DSP software involved in RNC system design
MCU tasks cover:
- Identification of CAN signals,
- Mode switching of DSP sound effects,
- Initialization of the AMP chip,
- Switching and identification of system operating modes.
DSP tasks cover:
- MIC data collection and processing,
- Sensor data collection and processing,
- Calculation of RNC noise reduction data.
RNC controller structure design
Size requirements:
- Dimensional design requires consideration of the installation space.
Protection requirements:
- Give priority to the cooling needs of the system.
- In addition, you need to consider the requirements of foot trample, water shower and so on.
- In order to ensure long-term reliable operation of the system, the system must perform thermal analysis and thermal testing.
Installation location requirements:
- It is recommended to put it under the main driving/secondary driving position, anti-stepping, anti-watering.
Frequency response requirements:
- There is a good frequency response in the noise reduction band.
Other requirements:
- Considering the need for heat dissipation, the controller needs to avoid the air.
RNC system error microphone
Error microphone selection and layout requirements:
Location requirements: close to the driver’s ear position, can be placed on the roof or seat headrest.
Quantity requirement: related to the number of reference point positions.
Direction requirements: point to the driver and passenger.
Frequency response requirements: It is necessary to cover the RNC control band, and it is not appropriate to introduce too many high frequency signals.
Noise signal spectrum
RNC system acceleration sensor
- Position requirement: Generally choose the suspension position of the chassis, which is hard and firm.
- Quantity requirements: based on the results of the data analysis (quantity-control effect curve).
- Direction requirement: Detect the acceleration values of the vehicle X, Y, Z in three directions.
- Protection requirements: Ensure that the Sensor and its connectors are waterproof.
- Noise requirements: There is enough dynamic range and low noise.
Vibration signal spectrum
RNC controller speaker
Speaker selection and layout requirements:
- Location requirements: door IF and woofer requirements.
- Quantity requirements: The minimum configuration is 4+2, which usually requires heavy bass.
- Direction requirements: Requirements directions: the normal configuration of the vehicle.
- Re-lower speaker body requirements: need to use a closed box (dynamic performance is better than the open box).
- Sound pressure level requirements: Reproduction sound pressure level needs to be greater than the car measurement position noise level by 10dB.
- Frequency requirements: the door speaker needs to cover 75~500hz, the subwoofer needs to cover 30-150hz, and has a reasonable flat frequency response.
- Resonance requirements: The installation is firm and the audible noise/resonance cannot be heard when the speaker is at maximum power output.
RNC system transfer function test
The system transfer function is defined as follows:
Sweep signal requirements: 20~500Hz sine.
RNC system calibration pavement
Calibration road requirements:
The rough asphalt road surface test is mainly used, and the smooth asphalt road and the cement road are secondary calibration road surfaces. When the test vehicle is required to drive at a constant speed on the designated road surface, the road surface can effectively excite the 100~400 Hz noise in the vehicle. The purpose of selecting various road surfaces is to make the noise reduction function more adaptable.
RNC system calibration conditions
Calibration requirements:
The calibration can be calibrated and evaluated for the noise reduction effect of road noise according to the requirements of the following table.
RNC controller parts production sampling
In order to prevent the RNC noise reduction controller from deteriorating or not working due to improper operation or other reasons during the production of parts and vehicles, the RNC controller will sample the noise reduction performance of the product during the trial production phase of the vehicle.
Specific requirements are as follows:
1. The sampled vehicle brand, model, powertrain, transmission, etc. should be consistent.
2. Effectively check the sensors and connections of the sampled vehicles.
3. The test road conditions should be consistent with the road conditions of the commissioning vehicle.
4. The test conditions should be consistent with the commissioning vehicle conditions.
5. The sample size is in accordance with the national standard GB 2828–2003, AQL=0.65 principle.
6. The commissioning vehicle performance level minus the prototype vehicle performance results can not be less than 0.5dBA.
Sampling consistency requires testing of the following conditions:
Noise reduction effect of 100km/h uniform smooth asphalt pavement.
ACOUTEC looks forward to working with you with the most professional knowledge, the best team and the most sincere attitude.If you have any questions about road noise control solutions, please contact sales@acoutec.com.
