Tilt Correction Using Kalman Filter for Vibration
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Solution Overview
Problem
Existing image pickup apparatuses struggle with accurate tilt correction, especially when hand shake or vibration is large, as the acceleration from shake is added to gravity acceleration, leading to incorrect tilt correction and image blur.
Innovation Solution
The apparatus includes a first angle calculating unit for acceleration, an analyzing unit for vibration state, a second angle calculating unit using angular velocity, and a correcting unit for performing tilt correction based on the second angle, employing a Kalman filter to differentiate between gravity and vibration acceleration, and adjusting the Kalman gain according to the vibration state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If tilt correction is performed using only accelerometer output signal, then highly accurate tilt correction is achieved when hand shake is small, but correction accuracy deteriorates when large vibration occurs
Solution Approach 1:
The patent combines the outputs of both the accelerometer and angular velocity detector through additive synthesis. The corrected tilt angle is calculated by adding the tilt angle from the accelerometer to the integrated angle from the angular velocity detector, weighted by a vibration-dependent coefficient. This merging allows the system to leverage the strengths of both sensors: the accelerometer provides accurate gravity reference when stationary, while the angular velocity detector provides stable integration results when vibrating.
Solution Approach 2:
The patent dynamically adjusts the synthesis coefficient based on the detected vibration state. When vibration is detected (acceleration exceeds threshold), the system increases the weight of the angular velocity detector's contribution and decreases the weight of the accelerometer's contribution. This dynamic adaptation allows the system to maintain high correction accuracy across varying operational conditions, transitioning smoothly between static and vibrating states.
2Measurement precision
If accelerometer is used for tilt detection, then gravity acceleration can be detected accurately, but vibration acceleration is incorrectly interpreted as gravity acceleration
Solution Approach 1:
The patent introduces a vibration detection mechanism that acts as an intermediary between the accelerometer output and the tilt correction process. This intermediary detects the presence of vibration by monitoring acceleration magnitude and uses this information to adjust the synthesis coefficient, thereby filtering out the harmful vibration component from the gravity detection process.
Solution Approach 2:
The system implements feedback by continuously monitoring the accelerometer output for vibration conditions and adjusting the synthesis coefficient accordingly. When vibration is detected, the feedback loop reduces the influence of the accelerometer data and increases reliance on the angular velocity detector, preventing vibration-induced errors from propagating to the final tilt correction.
3Reliability
If angular velocity detector is used for tilt correction, then vibration resistance is improved, but measurement accuracy decreases due to integration errors
Solution Approach 1:
The patent merges the outputs of both sensors with dynamically adjusted weights. The final tilt angle is synthesized by combining the accelerometer-based tilt angle and the angular velocity-based integrated angle, where the synthesis coefficient determines the contribution of each sensor. This merging allows the system to achieve both vibration resistance and measurement accuracy by leveraging the complementary strengths of both sensing approaches.
Solution Approach 2:
The patent changes the parameter (synthesis coefficient) based on vibration conditions to optimize performance. By adjusting the weight given to each sensor's output according to the detected vibration state, the system adapts its measurement parameters to maintain high accuracy across different operational conditions, effectively compensating for the integration errors of the angular velocity detector when vibration is present.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables highly accurate tilt correction even in large vibration states by effectively distinguishing between gravity and vibration-induced accelerations, ensuring that the image is captured with the intended orientation, reducing image blur and improving correction accuracy across a wide frequency band.
Implementation Method 1
an acceleration detector configured to detect an acceleration
Implementation Method 2
an angular velocity detector configured to detect an angular velocity
Implementation Method 3
an image pickup element configured to photoelectrically convert an optical image formed via an optical system to output an image signal
Data Source
AI summary
A control apparatus includes a first angle calculating unit configured to calculate a first angle based on an acceleration detected by an acceleration detector, an analyzing unit configured to analyze a vibration state based on at least one of the acceleration and an angular velocity detected by an angular velocity detector, a second angle calculating unit configured to calculate a second angle based on the angular velocity, the first angle, and the vibration state, and a correcting unit configured to perform tilt correction based on the second angle.