Active Vibration Noise Control With Variable Sampling Periods
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional active vibrational noise control systems face limitations in design flexibility and processing power requirements, particularly when dealing with fluctuating engine rotational speeds, leading to costly high-performance CPUs and restricted control ranges.
Innovation Solution
The system employs a waveform data table with discretized sine or cosine waves, allowing for real-number division to calculate sampling periods, which increases design freedom and reduces CPU processing power requirements by enabling a wider control range without necessitating high-performance CPUs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fixed sampling technology with fixed sampling period is employed, then the base signal can be generated with high resolution (0.1 Hz), but the storage means requires large storage capacity (40000 discrete waveform data) and is costly to manufacture
Solution Approach 1:
The patent applies variable sampling technology where the sampling period is dynamically adjusted according to the engine rotational speed. Instead of using a fixed sampling period that requires storing 40000 discrete waveform data points, the system calculates the sampling period based on the detected engine speed, significantly reducing the storage capacity requirement while maintaining frequency resolution capabilities.
2Quantity of substance
If variable sampling technology with sampling period variable in synchronism with engine rotational speed is employed, then the storage means can be of smaller storage capacity, but the noise canceling capability varies in the control range as the frequency of the base signal changes
Solution Approach 1:
The patent implements a feedback mechanism where the sampling period is calculated based on the detected base period of the engine rotational speed. The system continuously monitors engine speed and adjusts the sampling period accordingly, ensuring that the noise canceling capability remains effective across different operating conditions while maintaining stable performance throughout the control range.
3Quantity of substance
If the number of discrete waveform data for generating the base signal is reduced, then the storage means can be of smaller storage capacity, but the freedom of design is reduced and the number of waveform data must be a natural number
Solution Approach 1:
The patent changes the parameter of sampling period from a fixed value to a variable value that can be calculated based on the base period. This allows the system to use a smaller number of discrete waveform data points while maintaining design flexibility. The sampling period calculation enables real-number division and flexible control range design, removing the constraint that the number of waveform data must be a natural number.
4Adaptability or versatility
If the control range is widened, then the processing ability limit of CPU becomes more strict, but manufacturing cost increases
Solution Approach 1:
The patent uses variable sampling technology where the sampling period is dynamically adjusted according to the base period of the engine rotational speed. This dynamic adjustment allows the system to achieve a wider control range without requiring excessively high CPU processing ability, as the sampling period is optimized for each operating condition rather than requiring a fixed high-performance CPU configuration.
Data Source
AI summary
While a vehicle incorporating an active vibration noise control apparatus is decelerating, hysteresis is given if an operating point moves from an operating point on a sampling period characteristic curve to an operating point on another sampling period characteristic curve. Even if a base period detected depending on noise contains fluctuations, a smooth noise control process is performed. Since a division number produced when the base period is divided by a sampling period is a real number, the freedom of design is widened. Less strict limits are posed on the processing capability of a CPU of the active vibration noise control apparatus to provide a wider control range.