Time-Gated Rangefinder Using Three-Interval Signal Normalization
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Solution Overview
Problem
There is a need for a simple yet accurate rangefinding device that can be built using low-cost components while maintaining high accuracy in measuring object distances, as existing technologies often require complex and costly equipment.
Innovation Solution
A rangefinding device that emits a train of light pulses and detects reflected light during three time intervals of equal duration, integrating and normalizing the signals to determine the object's range using calibration data, allowing for accurate distance measurement with simpler hardware and lower procurement costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional time-gated detection schemes are used with multiple shutters and complex calibration, then measurement precision is improved, but device complexity increases and manufacturing costs rise
Solution Approach 1:
The detection process is segmented into three distinct time intervals (background gate, pulse energy gate, ranging gate) that are sequentially applied to different light pulses. This segmentation allows complex measurements to be broken down into simpler, manageable components that can be processed independently, reducing overall system complexity while maintaining precision.
Solution Approach 2:
The system uses periodic modulation of the detection gates synchronized with the light pulse train. By opening and closing gates at specific periodic intervals corresponding to pulse emission times, the system achieves precise time-gated detection without requiring complex continuous control mechanisms, thereby simplifying the device while improving measurement accuracy.
2Measurement precision
If high-precision rangefinding is achieved through complex time-gated detection, then measurement precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The detection system is designed to perform multiple functions using a single integrated approach: background subtraction, pulse energy measurement, and ranging detection are all achieved through the same time-gated detection hardware. This multi-functionality eliminates the need for separate specialized components for each measurement type, simplifying manufacturing while maintaining high precision.
Solution Approach 2:
The system uses the emitted light pulses themselves as reference signals for calibration and measurement. By comparing the pulse energy gate measurements with background gate measurements, the system automatically performs self-calibration without requiring external reference sources or complex manual calibration procedures, thereby improving ease of manufacture and deployment.
3Measurement precision
If three time-interval detection gates are used with normalization, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The system applies partial action by using three detection gates with different durations and timing windows rather than continuous detection. The background gate, pulse energy gate, and ranging gate are each optimized for specific measurement purposes with minimal necessary duration, reducing total energy consumption while achieving the required measurement precision through selective sampling rather than continuous monitoring.
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 method and device provide accurate range measurements with reduced electronic complexity and lower costs, enabling the use of standard CCD/CMOS light sensing devices and broader selection of light sources, while improving signal-to-noise ratio and dynamic range.
Implementation Method 1
emitting a train of light pulses from the rangefinding device toward the object for reflection thereby
Implementation Method 2
detecting light received by the rangefinding device during three time intervals
Data Source
AI summary
A rangefinding device and a method for determining the range of an object from a rangefinding device are provided. A train of light pulses each having an emission time and a pulse duration is generated. The pulse duration is set to twice the round-trip time to a maximum range of the device. The light pulses are reflected back toward the device by the object and detected according to three time intervals, respectively determined by a background gate, a ranging gate and a pulse energy gate. The light energy received during each interval is integrated and the integrated light value corresponding to the ranging gate is normalized using the values from the other two intervals. The range of the object is determined from the normalized ranging measurement and calibration data.