Bidirectional Delay Line Time-of-Flight Sensor
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Solution Overview
Problem
Current distance measurement technologies using the time-of-flight principle face challenges in achieving high accuracy due to the complexity and cost of hardware required for precise time measurement, particularly at resolutions of a hundred picoseconds, which limits their applicability in demanding applications like safety technology.
Innovation Solution
A sensor utilizing a pulse-based transit time method with a delay line fed from both sides, where the transmission and reception pulses converge and superimpose, allowing for identification of the node position indicating the transit time, enabling simple and robust measurement without the need for complex active components, and can be integrated with a microcontroller for evaluation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional TDC methods with high clock frequencies are used to achieve high measurement precision, then measurement precision improves, but device complexity increases
Solution Approach 1:
Instead of measuring time by counting clock cycles from a single direction, the patent inverts the approach by feeding the delay line from both ends simultaneously and detecting where the pulses meet. This bidirectional approach simplifies the measurement mechanism while maintaining high precision, avoiding the need for complex high-frequency clocking infrastructure.
Solution Approach 2:
The patent extracts the time measurement function from complex digital TDC circuits and implements it using a simple analog delay line with bidirectional pulse propagation. This separates the time measurement capability from the complex digital infrastructure, achieving high precision through a fundamentally simpler mechanism.
2Device complexity
If analog timing methods with capacitors are used to simplify the measurement process, then device complexity decreases, but measurement precision deteriorates
Solution Approach 1:
The patent creates a physical copy of the pulse signal that travels through the delay line from the opposite direction. By having two identical pulses (transmit and receive) propagate through the same delay line structure from opposite ends, the system achieves precise time measurement through the spatial overlap of these copies, maintaining simplicity while ensuring accuracy.
3Measurement precision
If tapped delay lines with many delay elements are used to achieve high measurement precision, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent applies bidirectional pulse propagation through the delay line, allowing the system to measure time by detecting where pulses from opposite ends meet. This inverts the conventional unidirectional approach and reduces the required number of delay elements, achieving high precision with a simpler structure.
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
This approach allows for cost-effective and precise distance measurement with improved time resolution, enabling accurate detection of objects and potentially expanding the range of applications in safety and automation technologies.
Implementation Method 1
A time-of-flight measuring unit determines the transit time between the transmit pulse and the receive pulse
Implementation Method 2
the transmit and receive pulses superimpose. At the node corresponding to this position, the signal amplitude is therefore greater than both the transmit and receive pulses
Data Source
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AI summary
A sensor (10) for determining a distance using a pulse-based time-of-flight method is described, comprising a transmitter (12) for emitting a signal pulse (14) triggered by a transmit pulse, a receiver (22) for generating a receive pulse from the remitted signal pulse (20), and a time-of-flight measuring unit (24) for determining the time of flight from the transmit pulse and the receive pulse. The measuring unit (24) has a delay line (26) with a plurality of delay elements (28) connected in series and nodes (30) between the delay elements (28). The time-of-flight measuring unit (24) is configured to feed the transmit pulse into the delay line at one end (32a) and the receive pulse into the other end (32b) and to determine the time of flight from the at least one node (30) with an amplitude corresponding to a superposition of the transmit pulse and the receive pulse.