Shape Measuring Apparatus Using Frequency-Domain Signal Separation
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Solution Overview
Problem
Conventional shape measuring apparatuses require separate displacement sensors for detecting contact force and surface profile, leading to a complex structure and increased costs.
Innovation Solution
A shape measuring apparatus that uses a single displacement sensor to detect both contact force and surface profile by separating high-frequency and low-frequency components of the probe displacement signal, allowing for constant contact force or distance maintenance and surface shape measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate displacement sensors are used for detecting contact force and surface profile, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent combines two separate displacement sensors into a single displacement sensor that measures the vertical displacement of the probe. By vibrating the probe at high frequency and separating the vibration signal from the surface profile signal through frequency analysis, the system achieves both contact force detection and surface profile measurement with one sensor, thereby reducing device complexity while maintaining detection accuracy.
Solution Approach 2:
The single displacement sensor is designed to perform multiple functions: it detects both the contact force (through high-frequency vibration amplitude changes) and the surface profile (through low-frequency vertical displacement). This multi-functional approach eliminates the need for separate sensors and reduces overall system complexity.
2Reliability
If separate displacement sensors are used for detecting contact force and surface profile, then measurement reliability is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges two separate sensor systems into one, reducing the number of components that need to be manufactured, assembled, and calibrated. This single sensor approach lowers manufacturing costs while the frequency-based separation method ensures reliable simultaneous measurement of both contact force and surface profile.
Solution Approach 2:
The displacement sensor is designed as a universal measurement device that can simultaneously provide contact force and surface profile information through signal processing. This eliminates the need to manufacture and integrate multiple specialized sensors, reducing overall system cost while maintaining measurement reliability.
3Device complexity
If a single displacement sensor is used to detect both contact force and surface profile, then device complexity is reduced, but signal processing complexity increases
Solution Approach 1:
The probe is vibrated at a high frequency (e.g., ultrasonic frequency) as it scans the surface. The vibration signal is superimposed on the surface profile signal in the displacement measurement. By using frequency separation, the contact force information (embedded in vibration amplitude) is distinguished from the surface profile information (low-frequency component), enabling simultaneous measurement with a single sensor.
Solution Approach 2:
The high-frequency vibration of the probe creates a periodic signal that can be easily separated from the lower-frequency surface profile signal through frequency domain analysis. This periodic vibration acts as a carrier that modulates the displacement signal, allowing extraction of contact force information while maintaining surface profile measurement 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
Simplifies the apparatus structure, reduces costs by eliminating the need for separate sensors, and maintains accurate contact force and surface profile detection.
Implementation Method 1
The displacement sensor measures the vertical displacement of the probe and outputs a probe displacement signal
Implementation Method 2
The minute-vibration generation section vibrates the probe up and down
Implementation Method 3
The signal processing section obtains information about the contact force or the distance between the surface to be measured and the probe from the high-frequency component, which corresponds to the vibration of the probe, of the probe displacement signal
Data Source
AI summary
A shape measuring apparatus includes a probe for scanning across a surface to be measured, while vibrating up and down; a minute-vibration generation section for vibrating the probe up and down; a vertical movement control section for moving the probe up and down to keep a constant contact force or a constant distance between the surface to be measured and the probe; a scanning section for scanning the surface to be measured with the probe; a displacement sensor for measuring the vertical displacement of the probe and outputting a probe displacement signal; and a signal processing section for obtaining information about the contact force or the distance between the surface to be measured and the probe from a high-frequency component of the probe displacement signal, and for obtaining information about profile of the surface to be measured from a low-frequency component of the signal obtained when the surface to be measured is scanned such that the distance or the contact force is kept constant.