Optoelectronic Sensor Angular Measurement via Optical Flow
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Solution Overview
Problem
Conventional laser scanners face challenges in accurately determining angular positions and maintaining reliability due to complex mechanisms and susceptibility to interference from dust and ambient light, which affects the accuracy and robustness of angle measurements.
Innovation Solution
An optoelectronic sensor system that replaces the conventional encoder disk with a moving or stationary image sensor, utilizing an optical flow method to determine angular positions and relative movement, integrated with a computing unit and illumination for robust and compact angle measurement, and capable of detecting front screen contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an encoder disk with regular openings and a fork light barrier is used for angle measurement, then angular position can be determined, but the device complexity increases and reliability decreases due to susceptibility to dust and ambient light interference
Solution Approach 1:
The patent replaces the mechanical encoder disk and fork light barrier system with an optical flow measurement system using an image sensor. Instead of mechanically rotating an encoder disk and detecting beam interruptions, the invention uses an image sensor to capture images of a structured light field and computes angular position through optical flow algorithms, thereby eliminating complex mechanical components and their susceptibility to dust and ambient light interference.
Solution Approach 2:
The patent creates an optical copy of the angular position information by projecting a structured light field and capturing it with an image sensor. The angular position is encoded in the spatial distribution of light in the image, allowing the system to measure angle without direct mechanical contact or vulnerable optical components.
2Measurement precision
If an encoder disk with regular openings is used for angle measurement, then angular position can be detected, but the reliability decreases due to individual openings being closed by interfering particles or dust
Solution Approach 1:
The patent replaces the mechanical encoder disk system with an optical flow measurement system using an image sensor. The image sensor captures a structured light field where angular position is encoded in the spatial pattern rather than in individual mechanical openings, eliminating the vulnerability to dust and interfering particles that would block specific openings in an encoder disk.
Solution Approach 2:
The image sensor serves multiple functions: it captures the structured light field for angular position measurement, provides redundancy through multiple measurement points across the entire sensor array, and can potentially detect other parameters. This multi-functionality increases reliability compared to a single-channel encoder disk system.
3Measurement precision
If a fork light barrier is used with an encoder disk for angle measurement, then rotational speed and angular position can be calculated, but the device complexity increases and the system becomes susceptible to ambient light interference
Solution Approach 1:
The patent replaces the fork light barrier mechanical system with an image sensor-based optical flow measurement system. The structured light field projected by the system provides a known reference pattern that allows the image sensor to distinguish between the projected light and ambient light, thereby eliminating susceptibility to ambient light interference while maintaining angular position and rotational speed measurement capabilities.
4Reliability
If a separate transmitter and receiver are used for front screen monitoring, then contamination detection is possible, but the device complexity increases
Solution Approach 1:
The patent makes the image sensor multi-functional by using it for both angular position measurement through optical flow and front screen contamination detection. The same image sensor that captures the structured light field for angle measurement also captures images of the front screen, allowing contamination detection without requiring a separate transmitter and receiver system, thereby reducing device complexity while maintaining reliability.
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
The solution enhances the robustness, reliability, and cost-effectiveness of angular measurements, reduces sensor size, and allows for additional features like ambient light measurement and contamination detection, improving overall sensor performance and meeting safety standards.
Implementation Method 1
utilizing an optical flow method to determine angular positions and relative movement
Implementation Method 2
a light beam generated by a laser periodically sweeps over a monitoring area by means of a deflecting unit. The light is remitted by objects in the monitoring area
Implementation Method 3
the laser scanner measures object distances on the basis of the time of flight between the transmission and reception of a single light pulse
Data Source
AI summary
An optoelectronic sensor (10) for detecting objects comprises a light transmitter (12) for transmitting a light beam (16), a rotatable deflection unit (18) for periodically deflecting the light beam (16), an angle measuring unit (30) for determining an angular position of the deflection unit (18), a light receiver (26) for generating a reception signal from a reflected light beam (22), wherein the angle measuring unit (30) comprises an image sensor (32) moving with the deflection unit and arranged in the direction of a stationary part (44, 46) of the sensor (10), or a stationary image sensor (32) arranged in the direction of the deflection unit (18), further comprising a computing unit (36) to determine a relative movement of the deflection unit (18) with respect to the sensor (10) from a signal of the image sensor (32).