Rotation Speed Measurement Using Acceleration and Magnetic Sensors
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Solution Overview
Problem
Existing rotation speed measuring systems for balls in midair struggle to automatically detect the end of midair movement, especially when the ball is caught or lands softly, as the frequency changes in earth magnetism measurements are not always rapid or significant.
Innovation Solution
Incorporating both a magnetic sensor to measure earth magnetism and an acceleration sensor to detect changes in acceleration, with an end detecting unit that identifies a switch from a small-variation to a large-variation state in acceleration, allowing for accurate detection of the end time point of midair movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If only a magnetic sensor is used to measure earth magnetism for calculating rotation speed, then the rotation speed can be calculated, but the system cannot automatically detect the end time point of midair movement when frequency changes are subtle or absent
Solution Approach 1:
The patent combines a magnetic sensor for measuring earth magnetism with an acceleration sensor for detecting acceleration variations. By merging these two sensing systems, the patent achieves both rotation speed measurement and automatic end time point detection, resolving the limitation of using only a magnetic sensor.
Solution Approach 2:
The acceleration sensor acts as an intermediary indicator to detect the end time point of midair movement. Instead of relying directly on frequency changes in magnetic sensor data, the system uses acceleration variations as an intermediate signal that clearly indicates when the ball lands or is caught, even when magnetic frequency changes are subtle.
2Extent of automation
If the system relies on frequency changes of earth magnetism measurement data to detect end time point, then automatic detection is possible in some cases, but detection fails when frequency changes are not rapid or significant
Solution Approach 1:
The patent changes the detection parameter from magnetic field frequency to acceleration magnitude. By monitoring changes in acceleration rather than frequency of magnetic signals, the system achieves reliable automatic detection of end time points across various scenarios including soft landings and catches where frequency changes are not pronounced.
3Difficulty of detecting and measuring
If an acceleration sensor is added to detect acceleration variations, then end time point detection is improved, but device complexity increases
Solution Approach 1:
The patent uses an acceleration sensor to detect mechanical changes (vibrations and movements) caused by the ball landing or being caught, replacing the need for complex mechanical switches or contact-based detection systems. This electronic sensing approach simplifies the overall device while improving detection capability.
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
Enables reliable and automatic detection of the end time point of midair movement, improving accuracy in calculating rotation speed by utilizing acceleration variations, even in cases where frequency changes in earth magnetism are subtle or absent.
Implementation Method 1
a magnetic sensor that is provided in the ball and measures earth magnetism at least in one axis direction
Implementation Method 2
an acceleration sensor that is provided in the ball and measures acceleration at least in one axis direction
Data Source
AI summary
A rotation speed measuring system includes a magnetic sensor, an acceleration sensor, an end detecting unit, and a calculating unit. The magnetic sensor measures earth magnetism in at least one axis direction. The acceleration sensor measures acceleration in at least one axis direction. The end detecting unit detects a time point of a switch at which an acceleration variation is switched to a large-variation state after a small-variation state, wherein the small-variation state corresponds to a state in which the acceleration variation is equal to or below a predetermined first threshold value and the large-variation state corresponds to a state in which the acceleration variation is equal to or above a predetermined second threshold value. The calculating unit calculates the rotation speed of the ball moving in midair by analyzing a frequency of measurement data on the earth magnetism acquired by the magnetic sensor until the end time point.