TDMA Spatial Sensor Synchronization Preventing ToF Cross-Talk
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Solution Overview
Problem
Time-of-Flight (ToF) sensors in autonomous robots experience false or corrupted measurements due to cross-talk when multiple robots operate in the same environment, as existing synchronization methods are not applicable for freely moving robots and require a wireless solution to prevent interference.
Innovation Solution
A spatial sensor synchronization system using a Time-Division Multiple Access (TDMA) communication system, where each spatial sensor is triggered sequentially within a determined active time period, utilizing electrical triggers to initiate measurements, ensuring no interference by aligning with a timing signal and delaying start times to avoid crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple ToF sensors measure at the same time, then measurement speed and productivity are improved, but cross-talk between sensors causes false or corrupted measurements
Solution Approach 1:
The patent implements periodic time-division multiplexing where each ToF sensor is assigned specific time slots for measurement. The synchronization system uses periodic triggering signals to activate sensors sequentially rather than simultaneously, ensuring that measurements occur in discrete periods without overlap. This resolves the contradiction by maintaining high measurement throughput through frequent time slots while preventing cross-talk through temporal separation.
Solution Approach 2:
The patent segments the measurement process by dividing time into distinct intervals assigned to different sensors. Each sensor operates in its designated time window, creating segmented measurement cycles. This segmentation allows multiple sensors to function concurrently without interference, as each sensor's active measurement period is separated from others, thus maintaining both productivity and reliability.
2Adaptability or versatility
If wireless synchronization is used for freely moving robots, then adaptability and ease of operation are improved, but synchronization precision and reliability become more difficult to maintain
Solution Approach 1:
The patent replaces cable-based mechanical synchronization with wireless electromagnetic signal transmission. The system uses wireless communication to transmit synchronization triggers and timing signals to moving robots, eliminating physical connections while maintaining synchronization capability. This substitution provides the needed adaptability for mobile robots while preserving reliability through robust wireless protocols and error correction mechanisms.
Solution Approach 2:
The patent implements feedback mechanisms where sensors report their status and timing information back to the synchronization system. This feedback loop allows the system to adjust and maintain synchronization accuracy despite the challenges of wireless communication and robot movement. The feedback ensures that timing deviations are detected and corrected, maintaining reliability while enabling wireless operation.
3Reliability
If sequential triggering is implemented to avoid cross-talk, then measurement reliability is improved, but measurement productivity decreases due to longer sequence periods
Solution Approach 1:
The patent applies partial action by having sensors remain in a low-power standby state between active measurement periods. Instead of continuous operation, each sensor is triggered only during its assigned time slot, reducing overall system activity while maintaining measurement capability. This allows the system to achieve reliable sequential measurements without the full productivity loss of traditional sequential systems, as sensors can quickly transition between states.
Solution Approach 2:
The patent uses preliminary action by pre-assigning time slots and triggers to each sensor in advance. The synchronization system prepares the measurement sequence beforehand, so when measurement time arrives, sensors are already positioned and ready to measure immediately. This preliminary preparation reduces the actual measurement time required, thereby maintaining higher productivity while still achieving reliable cross-talk-free measurements through the pre-planned sequential 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
The TDMA-based synchronization method effectively prevents false measurements by ensuring each ToF sensor completes its measurement without interference, even when multiple robots are operating in close proximity, thereby enhancing navigation and collision avoidance accuracy.
Implementation Method 1
Time of Flight (ToF) sensors
Implementation Method 2
c = 299 792 458 m/s
Data Source
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Figure 3~4
Figure 5
AI summary
A spatial sensor synchronization system using a Time-Division Multiple Access (TDMA) communication system, intended for a plurality of entities evolving inside the TDMA communication system, whereby each one of the plurality of entities is intended to comprise a spatial sensor and a tag enabled to communicate in the TDMA communication system, further whereby each spatial sensor is enabled to make a spatial measurement during a determined active time period, further whereby the tags from the plurality of entities are addressed in sequence by the TDMA communication system with a determined sequence period separating two subsequent addresses in the TDMA communication system. Each of the tags comprises electrical trigger output means configured to output an electrical trigger to the sensor of the corresponding entity at the time of being addressed by the TDMA communication system. Each of the sensors comprises electrical trigger input means connected to the electrical trigger output means, and configured to initiate a spatial sensor measurement for each received electrical trigger. A duration of the determined sequence period is equal or greater than a duration of the determined active time period.