Propeller Synchrophasing Over Asynchronous Bus Clock Domains
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Solution Overview
Problem
Existing fly-by-wire systems in aircraft face challenges in achieving accurate synchrophasing of propellers at high frequencies using lower frequency asynchronous buses due to uncertainties in message timing and lack of clock synchronization.
Innovation Solution
A synchronization system using asynchronous buses, where flight control computers and actuator control modules exchange timestamps to adjust their local clocks, ensuring synchronization accuracy within 1 microsecond, allowing precise control of propeller phase angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an asynchronous bus is used for communication between control modules, then the system complexity is reduced and reliability is improved, but clock synchronization between modules deteriorates, resulting in significant phase angle offset errors
Solution Approach 1:
The patent applies preliminary action by having the transmitting control module prepend timestamp information to each data message before transmission. This allows the receiving module to calculate transmission duration and compensate for clock frequency differences in advance, rather than dealing with synchronization errors after they occur. The timestamp is embedded in the message structure itself, enabling proactive correction of phase angle offsets.
2Measurement precision
If a higher-speed synchronous bus is used to achieve accurate synchrophasing, then phase angle control precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical/synchronous bus approach with an asynchronous communication system that uses software-based timestamp tracking and calculation. Instead of relying on hardware-level clock synchronization and high-speed synchronous buses, the system uses asynchronous messages with embedded timestamps and software algorithms to achieve the same synchrophasing precision, thereby reducing hardware complexity and cost.
3Measurement precision
If timestamp-based synchronization is implemented over an asynchronous bus, then phase angle control precision is maintained at low cost, but communication overhead increases
Solution Approach 1:
The patent merges the synchronization function with the existing data communication function. Instead of implementing a separate high-speed synchronous communication channel for synchronization, the system combines clock timing information (timestamps) with the regular asynchronous data messages. This allows synchronization data to be transmitted along with control commands or status information, eliminating the need for dedicated synchronization communication channels and reducing overall communication overhead.
Data Source
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AI summary
Vehicle systems and methods are provided for synchronizing control modules over a communications bus for synchrophasing propellers. A vehicle electrical system includes a communications bus, a bus control module to transmit a first message over the communications bus, a vehicle control module coupled to the bus control module to identify a first timestamp associated with the first message being transmitted in a first clock domain associated with the vehicle control module and provide a subsequent message to the bus control module including the first timestamp, and an actuator control module coupled to the communications bus to identify a second timestamp associated with the first message being received over the communications bus and determine an adjustment to synchronize a second clock domain associated with the actuator control module with the first clock domain based at least in part on a relationship between the first timestamp and the second timestamp.