Master-Slave Sensor Synchronization for High-Speed Detection
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Solution Overview
Problem
The existing object detection systems with multiple-optical-axis photoelectric sensors require inter-sensor and in-sensor communication in every detection process, making it difficult to shorten the cycle of detection processes and thereby limiting processing speed.
Innovation Solution
The system employs a master device with timers and definition information to synchronize detection processes across multiple sensors, eliminating the need for inter-sensor communication by determining and transmitting operation timings, allowing each device to execute detection processes independently based on stored definition information and corrected timers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If inter-sensor communication and in-sensor communication are performed in every detection process, then detection accuracy and coordination between sensors are maintained, but the detection process cycle cannot be shortened and processing speed is limited
Solution Approach 1:
The master device pre-calculates and transmits definition information (including waiting times and operation timings) to all devices before the detection process begins. This preliminary setup allows devices to execute detection processes independently without continuous communication, thereby maintaining detection accuracy while enabling high-speed parallel processing across multiple sensors
Solution Approach 2:
The master device creates copies of the detection process timing information and distributes them to all slave devices. Each device receives a copy of the definition information that specifies its operation timing, allowing independent execution without real-time communication, thus resolving the contradiction between maintaining coordination accuracy and achieving high processing speed
2Reliability
If continuous communication between sensors is maintained, then detection process coordination is ensured, but system complexity and communication overhead increase
Solution Approach 1:
The communication function is extracted from the continuous operation and concentrated into a single pre-process step where the master device transmits definition information to all slave devices. After this initial communication, devices operate independently using stored timing information, eliminating the need for continuous communication while maintaining coordination reliability and reducing system complexity
3Device complexity
If detection processes are executed sequentially across multiple sensors, then communication coordination is simplified, but the overall detection cycle time increases
Solution Approach 1:
The system implements periodic detection processes where each device executes detection at specifically assigned time intervals defined by the waiting time information. The master device coordinates the periodic execution by transmitting definition information that specifies when each slave device should perform detection, enabling parallel periodic operations that reduce total cycle time while maintaining simple communication coordination
Solution Approach 2:
The system dynamically assigns different waiting times to different devices based on their positions in the detection sequence. The master device calculates optimal waiting times for each slave device to achieve parallel execution without conflict, allowing the system to adapt the detection schedule dynamically rather than using fixed sequential timing, thereby reducing overall detection cycle time
Data Source
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AI summary
In an object detection system in which a projector or an optical receiver (optical receiver 2A) of a plurality of multiple-optical-axis photoelectric sensors (SA, SB, and SC) is defined as a master device and the other devices are defined as slave devices, a master device 2A produces pieces of definition information that determines timings of detection processes in the device including the master device and transmits the pieces of definition information to the slave device. The master device (2A) simultaneously transmits commands to request operations of internal timers to be synchronized with each other to the other slave devices in response to a lapse of a time corresponding to a period in which a circulating period of the detection processes of the sensors proceeds by a predetermined number of cycles. Each of the slave devices corrects the timer in response to the command, and determines a timing at which a detection process should be performed with reference to a time point for correction on the basis of the definition information matching the respective device to execute the detection process. The master device (2A) also determines a timing at which a detection process should be performed on the basis of the definition information matching the respective device to execute the detection process.