Actuator Control Linear Interpolation Noise Suppression
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Solution Overview
Problem
In image pickup devices, feedback control using digital signal processing from ADC and digital signal processing circuits within the audible range leads to audible driving noise, and increasing sampling frequencies result in increased circuit scale and power consumption.
Innovation Solution
An actuator control apparatus that includes an analog-digital conversion circuit, a servo circuit, and a sampling circuit capable of linearly interpolating servo control data, allowing the actuator to be driven with a sampling period shorter than the ADC sampling period, effectively doubling the sampling frequency without increasing ADC and servo circuit speeds or power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the ADC sampling frequency is increased to suppress audible driving noise, then the driving noise becomes inaudible, but the circuit scale and power consumption increase
Solution Approach 1:
The patent divides the sampling process into two stages: first, the ADC samples at a lower frequency (first sampling period), then a dedicated sampling circuit performs linear interpolation to generate additional sampling points at a higher effective frequency (second sampling period). This segmentation allows the system to achieve high-frequency noise suppression without requiring the entire ADC and digital signal processing circuit to operate at high frequencies, thus reducing power consumption.
Solution Approach 2:
The patent introduces an intermediary sampling circuit between the ADC and the digital signal processing circuit. This sampling circuit performs linear interpolation on the servo control data, effectively doubling the sampling frequency without increasing the ADC's operating frequency. The intermediary handles the frequency multiplication task, allowing the power-consuming ADC to operate at lower frequencies while still achieving high-frequency noise suppression.
2Object-affected harmful factors
If the ADC sampling frequency is increased to suppress audible driving noise, then the driving noise becomes inaudible, but the circuit scale increases
Solution Approach 1:
The patent segments the high-frequency sampling function into a dedicated sampling circuit that performs linear interpolation, rather than requiring the entire ADC system to operate at high frequencies. This segmentation achieves the noise suppression benefit while keeping the main ADC circuit scale small.
Solution Approach 2:
The sampling circuit creates additional sampling points by linearly interpolating between existing ADC samples. Instead of requiring the ADC to physically sample at higher frequencies (which would increase circuit scale), the system creates virtual sampling points through mathematical interpolation, effectively doubling the sampling frequency without proportionally increasing hardware complexity.
3Object-affected harmful factors
If the digital signal processing operation frequency is increased to suppress audible driving noise, then the driving noise becomes inaudible, but the power consumption increases
Solution Approach 1:
The patent separates the sampling function from the digital signal processing function. The sampling circuit performs linear interpolation at high effective frequency to generate densely-sampled servo control data, while the digital signal processing circuit operates at the lower ADC frequency. This segmentation allows noise suppression without requiring the power-consuming digital signal processing circuit to operate at high frequencies.
Solution Approach 2:
The sampling circuit acts as an intermediary that prepares high-resolution servo control data for the digital signal processing circuit. By performing linear interpolation before digital signal processing, the system achieves high-frequency noise suppression while the digital signal processing circuit maintains its lower, more power-efficient operating frequency.
4Measurement precision
If the ADC sampling frequency is increased to improve positional control precision, then the positional control becomes more accurate, but the power consumption increases
Solution Approach 1:
The patent segments the high-precision sampling function into a dedicated sampling circuit that performs linear interpolation. This allows the system to achieve high positional control precision through densely-sampled servo control data without requiring the power-consuming ADC to operate at high frequencies.
Solution Approach 2:
The sampling circuit creates additional sampling points through linear interpolation, effectively copying and expanding the sampling data at higher resolution. This provides the digital signal processing circuit with densely-sampled data for accurate positional control while the ADC itself continues to operate at lower, more power-efficient frequencies.
Data Source
AI summary
An actuator control apparatus includes an analog-digital conversion circuit, a servo circuit, a sampling circuit, and a driving circuit. The analog-digital conversion circuit is configured to sample a position detection signal with a first sampling period, convert the sampled signal into a digital signal, and output the digital signal, the position detection signal outputted from a position sensor corresponding to a position of a control target. The servo circuit is configured to calculate a displacement amount, by which the control target is to be displaced by an actuator, and output first servo control data corresponding to the calculated displacement amount, based on the position detection signal converted into the digital signal. The sampling circuit is configured to linearly interpolate the first servo control data, and output second servo control data sampled with a second sampling period shorter than the first sampling period.