Synchronous Data Communication Packet Structure
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Solution Overview
Problem
Conventional communication systems, such as those used in robot-assisted surgery, face challenges with high bandwidth requirements, strict synchronization, and reliability, particularly due to the cumbersome setup and maintenance of multiple communication paths, and inadequate synchronization capabilities, which can lead to lag and potential patient injury.
Innovation Solution
A data packet structure with a synchronization field, acknowledgement field, response field, header field, sequence number field, data field, end of packet field, and error-checking field is implemented, allowing for precise synchronization, low latency, and error detection and recovery, enabling efficient data transmission over a single physical path with flow-control information and fault signal propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hundreds of communication paths are used to connect control console to robotic arms, then communication bandwidth and reliability are improved, but system complexity and setup maintenance difficulty increase substantially
Solution Approach 1:
The patent consolidates hundreds of communication paths into a single serial communication channel by implementing a time-division multiplexed packet switching system. Data packets from multiple sources are multiplexed onto one physical path, with each packet containing routing information to identify its destination. This merging approach maintains the reliability of multiple paths while eliminating their physical complexity.
Solution Approach 2:
The single communication path is designed to handle multiple functions simultaneously - transmitting data from multiple robotic arms, control signals, sensor feedback, and diagnostic information all through one universal channel. The packet structure includes universal fields for routing, synchronization, and error checking that work across all communication types.
2Reliability
If conventional IEEE-1394 interface standard is used for serial communication, then point-to-point communication is provided with guaranteed bandwidth, but synchronization precision is limited to approximately 125 microseconds
Solution Approach 1:
The patent incorporates a synchronization field at the beginning of each data packet containing a predetermined shift-invariant value. This preliminary synchronization marker allows the receiving end to align its timing before processing the actual data, achieving synchronization precision of 10 microseconds or better without compromising bandwidth guarantees.
Solution Approach 2:
The invention changes the synchronization parameter from IEEE-1394's 125 microsecond granularity to a continuous timing reference embedded in each packet. By including timestamp information and sequence numbers in the packet header, the system achieves much finer synchronization precision while maintaining the guaranteed bandwidth of serial communication.
3Productivity
If data transmission continues without waiting for acknowledgements, then productivity and data flow are improved, but data reliability and error recovery capability deteriorate
Solution Approach 1:
The patent implements an acknowledgement field in each data packet that provides feedback to the transmitting end. When the receiving end correctly receives a packet, it sends back an acknowledgement signal. This feedback mechanism allows the system to maintain high productivity by using selective repeat ARQ - only retransmitting packets that were not correctly received, rather than waiting for acknowledgements before continuing transmission.
Solution Approach 2:
The system maintains continuous data flow by allowing multiple packets to be in transit simultaneously without waiting for acknowledgements. The sliding window protocol enables the transmitter to send a sequence of packets before receiving acknowledgements, ensuring continuous useful action while maintaining reliability through the acknowledgement feedback mechanism.
Data Source
AI summary
A data packet is provided that includes a synchronization field and an acknowledgement field indicative of an acknowledgement of receipt of a prior data packet. The data packet also includes a response field that includes information indicative of a system fault, a header field, and a sequence number field that includes a number assigned to the data packet. The data packet further includes a data field, an end of packet field, and an error-checking field. Methods and computer program products are provided that, in some implementations, include retransmitting packets if the acknowledgement field in a received data packet is a no acknowledgement (NAK) and/or placing a node into a safe state in response to a fault signal that is included in the received data packet.