Processor Timebase Synchronization via Pulsed Signal Injection
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Solution Overview
Problem
In multi-processor sensing systems, such as those used in autonomous vehicles, the lack of synchronization between processors' reference clocks leads to skew errors in composite sensor data, resulting in incorrect object detection and navigation.
Innovation Solution
A mechanism is introduced where a synchronization pulse is simultaneously injected into multiple processors, allowing each processor to record a timestamp according to its reference clock. These timestamps are then used to compute time offsets, which are applied to synchronize the processors' reference clocks or correct sensor timestamps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple processors operate with independent reference clocks to enable parallel processing, then processing speed and system productivity are improved, but timing synchronization between processors deteriorates, leading to skew errors in composite sensor data
Solution Approach 1:
The system implements a feedback mechanism where a central controller distributes synchronization pulses to multiple processors, each processor records the arrival time of these pulses using its local reference clock, and the controller collects these timestamp records to calculate and distribute time offset corrections. This closed-loop feedback ensures that despite independent operation, all processors maintain synchronized timing references, resolving the contradiction between parallel processing independence and timestamp synchronization accuracy.
Solution Approach 2:
A central controller acts as an intermediary between the independent processors and the synchronization pulse source. The controller receives synchronization pulses, determines their arrival times at each processor using recorded timestamps, calculates time offsets, and distributes correction values to processors. This intermediary coordinates the timing across all processors without requiring them to share a common clock, enabling both parallel operation and synchronized timing.
2Reliability
If processors use independent reference clocks to maintain operational autonomy, then system reliability and ease of operation are improved, but timing consistency across processors deteriorates, causing errors in composite sensor data
Solution Approach 1:
The system performs preliminary synchronization by distributing synchronization pulses to processors before actual sensing operations begin. Each processor records the arrival time of these preliminary pulses and receives pre-calculated time offset corrections. This preliminary action ensures that processors are synchronized before generating sensor data, maintaining both operational autonomy and timing consistency throughout the sensing process.
Solution Approach 2:
The central controller continuously monitors timing consistency by collecting timestamp records from processors and calculating time offsets. This feedback loop allows the system to detect and correct timing drift while processors maintain independent operation, ensuring both reliability through operational autonomy and stability through consistent timing.
Data Source
AI summary
A method and system to provide timebase synchronization for multiple processors in a multi-processor sensor system, where each processor operates according to a respective reference clock, and where the processors' respective reference clocks are off sync from each other. An example method includes simultaneously injecting a synchronization pulse respectively into the multiple processors. Further, the method includes recording for each processor, according to the processor's respective reference clock, a respective synchronization-pulse timestamp of the simultaneously injected synchronization pulse, comparing the respective synchronization-pulse timestamps recorded for the processors, and, based on the comparing, computing for each processor a respective time offset. Additionally, the method includes using the per-processor computed time offsets as a basis to provide a synchronized timebase across the processors.