Ethernet Sensor Synchronization via Timestamped Packet Control
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Solution Overview
Problem
Existing Ethernet communication systems face challenges in controlling sensors with high time accuracy, particularly in networks with variable latency, such as those using Energy-Efficient Ethernet (EEE).
Innovation Solution
The proposed solution involves using a controller with a transceiver and processor to generate and transmit packets containing control data and timestamps. These timestamps, including trigger timestamps, transport timestamps, and presentation timestamps, ensure that control data is delivered and sensor data is presented at precise future times, accounting for network latency and energy efficiency protocols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If Energy-Efficient Ethernet (EEE) protocols are used to reduce power consumption, then energy efficiency is improved, but time accuracy for sensor control deteriorates due to variable latency
Solution Approach 1:
The system performs preliminary actions by generating trigger timestamps that indicate future delivery times before the actual data transmission occurs. The controller calculates these timestamps in advance, accounting for expected network latency, and buffers the control data until the precise delivery time is reached. This preliminary timing calculation enables deterministic sensor control even when using energy-efficient Ethernet protocols that introduce variable latency.
Solution Approach 2:
The patent introduces timestamps as an intermediary mechanism between the controller and sensor. These timestamps (trigger timestamps, presentation timestamps, and capture timestamps) serve as mediators that carry timing information through the variable-latency Ethernet network, allowing the sensor and controller to synchronize their operations despite the unpredictable network delays introduced by EEE protocols.
2Measurement precision
If packets are buffered until future delivery times to ensure time accuracy, then time accuracy is improved, but device complexity increases due to buffering and timestamp management
Solution Approach 1:
The timestamp mechanism serves multiple functions simultaneously: it acts as a timing reference, a scheduling indicator, and a synchronization signal. The same timestamp fields in the Ethernet packets are used by the controller to determine when to send data, by the network to prioritize traffic, and by the sensor to know when to process the data. This multi-functionality reduces the need for separate complex control mechanisms.
3Measurement precision
If deterministic latency is achieved through timestamp-based control, then time accuracy is improved, but network complexity increases due to additional timestamp fields and processing
Solution Approach 1:
The patent changes the parameter representation by using standardized Ethernet timestamp fields that can be processed by existing network infrastructure. Rather than introducing entirely new complex protocols, the solution modifies existing packet parameters to include timing information, allowing deterministic control to be achieved through parameter enrichment rather than structural complexity.
Data Source
AI summary
An apparatus for controlling sensors over a network includes a transceiver and a processor. The transceiver is configured to communicate over the network. The processor is configured to generate a first packet including a first timestamp destined to a first sensor, and generate a second packet including a second timestamp destined to a second sensor. The first and second timestamps are indicative of first and second future times that are set to synchronize operation of the first and second sensors. The processor is further configured to send the first and second packets to the network.