TOF Pulse Timing Control to Minimize Multi-Device Interference
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Solution Overview
Problem
In time-of-flight (TOF) based distance measuring techniques, cross interference occurs when multiple devices perform measurements simultaneously due to the reception of reflected light signals from other devices, necessitating improved methods to avoid synchronization issues.
Innovation Solution
A TOF based distance measuring method and system that intermittently transmits pulses with a non-fixed transmission period and performs continuous signal sampling, using a control circuit to vary the transmission period in real time, thereby reducing cross interference while maintaining consistent power levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple devices perform TOF based distance measurement simultaneously using pulse modulation, then distance measurement can be performed, but cross interference occurs between devices
Solution Approach 1:
The patent applies dynamics by making the transmission period variable rather than fixed. The control circuit dynamically adjusts the transmission period of light pulses based on timing information from previous pulses, creating a non-uniform pulse transmission pattern that prevents synchronization with other devices and eliminates cross interference
Solution Approach 2:
The patent changes the transmission period parameter from a fixed value to a variable value. By modifying the transmission period based on the time difference between adjacent pulses and adding a non-zero offset, the system transforms a static parameter into a dynamic one that adapts to prevent interference
2Object-affected harmful factors
If the transmission period is made variable to avoid cross interference, then cross interference is reduced, but the complexity of the control system increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating the transmission period for the next pulse based on the time difference from the previous pulse. The control circuit uses the timing information from received pulses to determine when to transmit the next pulse, preparing the transmission schedule in advance based on past timing data
Solution Approach 2:
The system applies self-service by using its own timing measurements to control its own pulse transmission. The distance measuring device uses the time difference information from its own pulse transmissions and receptions to automatically adjust its own transmission period, making the system self-regulating without external control
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 effectively minimizes cross interference between distance measuring systems without altering the average power or requiring additional calibration, facilitating mass production and reducing complexity and cost.
Implementation Method 1
time-of-flight (TOF) measures the distance of the target by the time difference between the transmission and reception of light pulses
Data Source
AI summary
A time-of-flight based distance measuring method and distance measuring system. The distance measuring method includes: intermittently transmitting a plurality of pulses from a pulse generation unit, wherein the plurality of pulses have a fixed pulse length but a non-fixed transmission period, and the plurality of pulses are reflected from a target to generate a plurality of reflected signals; controlling a TOF sensor to correspondingly perform a signal sampling for a predetermined time on the plurality of reflected signals respectively, based on a transmitting time of the plurality of pulses, to generate a sampling result according to a sampling time interval; detecting TOFs of the plurality of pulses from the pulse generation unit to the TOF sensor according to the sampling result; and determining a distance between the target and a reference position according to the TOFs.