Orientation Calculation Using Sensor Fusion to Correct Gyroscope Drift
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Solution Overview
Problem
Existing orientation calculation methods using gyroscopes in input devices suffer from errors due to slow movement detection failures, high angular rate limitations, abrupt rate changes, and 'drift' errors, leading to inaccurate orientation calculations.
Innovation Solution
An orientation calculation apparatus that includes gravitational direction calculation, motion acceleration calculation, and correction means to accurately calculate the orientation of an input device using both angular rate and acceleration data, with multiple correction processes to refine the gravitational vector and orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the gyroscope is used to calculate orientation, then the orientation can be obtained, but errors occur due to slow movement detection failures, high angular rate limitations, abrupt rate changes, and drift errors
Solution Approach 1:
The patent combines gyroscope data with acceleration sensor data to calculate orientation. The acceleration sensor detects gravitational acceleration to determine the gravitational direction, which is then integrated with gyroscope angular rate data to compute the final orientation, thereby compensating for gyroscope errors through multi-sensor fusion
Solution Approach 2:
The patent uses acceleration sensor data as feedback to correct gyroscope-derived orientation. The gravitational direction calculated from acceleration data serves as a reference to detect and correct drift errors in the gyroscope output, creating a closed-loop error compensation mechanism
2Measurement precision
If the gyroscope detects angular rate, then orientation can be calculated, but the error is cumulatively added over time leading to increased orientation error
Solution Approach 1:
The acceleration sensor provides continuous feedback on the gravitational direction, which is used to detect and correct drift errors in the gyroscope output. This feedback mechanism prevents error accumulation by periodically resetting the orientation calculation based on the reliable gravitational reference
Solution Approach 2:
The patent calculates the gravitational direction using the acceleration sensor before integrating it with the gyroscope data. This preliminary determination of the gravitational reference frame allows the system to pre-correct for potential drift errors before they accumulate in the orientation calculation
3Measurement precision
If only gyroscope data is used for orientation calculation, then the calculation is simple, but the orientation may not be accurately calculated
Solution Approach 1:
The patent merges gyroscope angular rate data with acceleration sensor data in a unified orientation calculation framework. The gravitational direction from the acceleration sensor and the angular rate from the gyroscope are combined to compute the final orientation, achieving accurate results through multi-sensor integration
Data Source
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AI summary
A game apparatus calculates a gravitational vector Vg, which represents a gravitational direction viewed from an input device, based on operation data. Then, a motion acceleration vector VA, which represents an acceleration applied by a motion of the input device, is calculated based on an acceleration represented by acceleration data and the gravitational vector Vg. The gravitational vector Vg is corrected such that the motion acceleration vector VA approaches a motion acceleration (vector VA') satisfying a relationship with an angular rate (vector Vω) represented by angular rate data, the relationship being predefined between the motion acceleration and the angular rate for the input device making a predeterminedmotion (rotational motion). Furthermore, the game apparatus calculates an orientation of the input device corresponding to the corrected gravitational vector.