CAN Bus Frame Collision Rate Calculation Using Erlang B Formula
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Solution Overview
Problem
Existing CAN bus systems lack a method to calculate frame collision rates, leading to inefficient resource utilization and increased communication latency due to frame collisions, which cannot be optimized without specific algorithms.
Innovation Solution
A frame collision rate calculation method using the Erlang B formula in queuing theory to determine the minimum CAN bus resources required to maintain a frame collision rate below a specified threshold, optimizing resource allocation by iteratively adjusting the bus communication rate based on priority traffic loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frames are sent periodically or random waiting time is added to prevent frame collisions, then frame collision reliability is improved, but communication efficiency deteriorates and communication resources are wasted
Solution Approach 1:
The patent implements feedback by calculating the frame collision rate based on actual bus load conditions and using this information to dynamically adjust transmission strategies. The system continuously monitors collision rates and adjusts frame sending parameters accordingly, transforming the open-loop periodic transmission into a closed-loop adaptive system that optimizes both reliability and efficiency.
Solution Approach 2:
The patent changes transmission parameters dynamically based on calculated collision rates. Instead of using fixed periodic intervals or random waiting times, the system adjusts frame transmission parameters (such as timing and frequency) based on real-time bus conditions, thereby optimizing communication efficiency while maintaining reliability.
2Productivity
If bus load rate is increased to utilize more communication resources, then communication capacity is improved, but frame collision probability increases
Solution Approach 1:
The system uses feedback by continuously calculating the frame collision rate based on actual bus load conditions. This calculated collision rate feeds back into the transmission control mechanism, allowing the system to adjust its behavior dynamically. When collision rates rise due to increased bus load, the system can adjust parameters to maintain reliability while preserving high communication capacity.
Solution Approach 2:
The patent transforms the static bus load rate into a dynamic parameter that can be adjusted in real-time. By calculating collision rates based on actual traffic conditions and adjusting transmission parameters dynamically, the system achieves both high communication capacity and low collision probability, resolving the contradiction between productivity and reliability.
3Reliability
If multiple wire harnesses are used for different communication systems, then system reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies merging by enabling multiple communication systems to share a single CAN bus through priority-based arbitration and collision rate calculation. Instead of requiring separate wire harnesses for each system, the invention allows concurrent access to the shared bus with different priorities, reducing wiring complexity while maintaining system reliability through the calculated collision rate management.
Data Source
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AI summary
The present invention discloses a frame collision rate calculation method for a frame on a CAN bus, and a CAN bus resource minimization method. The CAN bus resource minimization method includes: S1, setting an initial CAN bus communication rate; S2, at the preset rate in step S1 and on the basis of an Erlang B formula in the queuing theory, calculating a frame collision rate of a frame of each priority, the running of which on a CAN bus is planned; S3, determining whether the frame collision rate of the frame of each priority calculated in step S2 exceeds a frame collision rate upper limit allowed by the frame of the priority; if so, increasing the CAN bus communication rate in step S1, and proceeding to step S2 to continue the cycle; and if not, decreasing the CAN bus communication rate in step S1, and proceeding to step S2 to continue the cycle; and S4, outputting a minimum communication rate corresponding to not exceeding the frame collision rate upper limit allowed by the frame of each priority, so as to complete optimization. In the present invention, an algorithm for frame collision rates is provided, and thus required minimum bus resources are calculated according to a frame collision rate upper limit of a frame of each priority, such that resources are optimized.