TOF Distance Measurement Device Interference Avoidance
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Solution Overview
Problem
Existing distance measurement systems using Time of Flight (TOF) methods face interference issues when multiple devices are used simultaneously, leading to measurement errors and reduced measurement rates, as they struggle to avoid light interference without compromising the number of devices or measurement efficiency.
Innovation Solution
A distance measurement device and system that includes a controller to determine interference by calculating distance variations and setting optimal light emission and exposure periods for each device, allowing for reliable interference avoidance without reducing measurement rates, even with a large number of devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple distance measurement devices are used simultaneously in the same measurement space, then the quantity of devices increases and measurement coverage improves, but light interference occurs between devices causing measurement errors
Solution Approach 1:
The patent implements periodic action by assigning different light emission periods to multiple distance measurement devices. Each device emits light and performs exposure in synchronized cycles, with the controller coordinating the timing so that devices operate in alternating phases. This periodic coordination prevents simultaneous light emission and exposure across devices, eliminating cross-interference while maintaining high measurement rates and enabling accurate distance measurement with multiple devices operating in the same space.
2Reliability
If light emission and exposure durations are shifted between devices to avoid interference, then measurement accuracy improves, but the measurement rate decreases due to reduced operational time
Solution Approach 1:
The controller implements periodic action by establishing synchronized light emission and exposure cycles for multiple devices. Each device operates in coordinated phases where one device emits light while another performs exposure, then alternates in subsequent cycles. This periodic coordination ensures that light emission and exposure durations never overlap between devices, preventing interference while maintaining continuous operation and high measurement rates.
Solution Approach 2:
The system maintains continuity of useful action by ensuring that while one device is in light emission phase, another device is in exposure phase, and vice versa. This alternating pattern ensures that measurement operations continue without interruption across the device array, preventing idle time and maintaining high measurement throughput while eliminating interference through proper temporal separation.
3Reliability
If the interval of light emission and exposure durations is increased to avoid interference, then measurement accuracy improves, but the measurement rate is reduced
Solution Approach 1:
The controller implements periodic action by establishing synchronized light emission and exposure cycles for multiple devices. Each device operates in coordinated phases where one device emits light while another performs exposure, then alternates in subsequent cycles. This periodic coordination ensures that light emission and exposure durations never overlap between devices, preventing interference while maintaining continuous operation and high measurement rates.
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 system effectively identifies and avoids interference between devices, ensuring accurate distance measurements and maintaining high measurement rates, even when multiple devices are used, by dynamically adjusting light emission and exposure periods based on interference detection results.
Implementation Method 1
a distance measurement imaging device (hereinafter, distance measurement device) that uses a method (Time of Flight (TOF)) for measuring a distance by a time of flight until irradiation light is reflected by the object to return to the device
Implementation Method 2
measuring a distance by a time of flight until irradiation light is reflected by the object to return to the device
Implementation Method 3
a light receiving unit that exposes the pulsed light, which is reflected by the object, to an image sensor to convert the pulsed light into an electric signal
Data Source
AI summary
A distance measurement device includes a light emitting unit; a light receiving unit; a distance calculation unit that calculates a distance to an object; and a controller that controls the light emitting unit and the light receiving unit to determine whether or not there is interference from another distance measurement device, from a distance calculation result from the distance calculation unit. The controller includes a light emission and exposure period-setting unit that sets a light emission and exposure period of the light emitting unit and the light receiving unit, a distance variation measurement unit that measures a variation of distance values repeatedly obtained in a predetermined duration by the distance calculation unit, and an interference determination unit that compares a distance variation value to a threshold value which is determined in advance, to determine whether or not there is interference.