Smart CAN Termination via Dynamic Impedance Monitoring

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Solution Overview

Problem

Existing techniques for maintaining the performance of a Controller Area Network (CAN) bus are inadequate when terminating nodes are lost, leading to degraded signal quality and reduced electromagnetic compatibility, as re-routing or double termination methods are not optimal.

Innovation Solution

A computerized tool that monitors the CAN bus impedance, determines the loss of terminating nodes, and electronically converts non-terminating nodes to terminating nodes by adjusting switchable terminating resistors, ensuring the CAN bus remains properly terminated.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If re-routing or double termination methods are used to repair CAN bus performance, then the CAN bus can function when terminating nodes are lost, but the signal quality and electromagnetic compatibility are degraded

Engineering Contradiction:
ImproveCAN bus functionalityVSAvoidsignal quality and electromagnetic compatibility
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements dynamic termination by making terminating nodes selectable through switches. The system continuously monitors impedance to detect lost terminating nodes and dynamically reconfigures the network by activating backup terminating nodes. This dynamic adaptation maintains both functionality and signal quality without requiring static re-routing or permanent double termination, thereby resolving the contradiction between reliability and signal quality.

Inventive Principle:
Principle #15Dynamics

2Stability of the object's composition

If terminating nodes are lost, then the CAN bus structure remains intact, but performance is negatively affected

Engineering Contradiction:
ImproveCAN bus structureVSAvoidCAN bus performance
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The patent implements prior cushioning by providing backup terminating nodes that are pre-configured but initially inactive. When a terminating node is lost, the system detects the impedance change and activates the corresponding backup terminating node. This preparatory measure ensures that performance is automatically restored without manual intervention, maintaining both structural integrity and functional reliability.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Adaptability or versatility

If switchable terminating resistors are implemented at each node, then dynamic termination is enabled, but device complexity increases

Engineering Contradiction:
Improvedynamic termination capabilityVSAvoidnumber of switches and resistors
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the CAN bus into multiple segments, each with its own switchable terminating resistor. This modular approach allows the system to activate only the specific terminating nodes needed for each configuration scenario. Instead of requiring all nodes to have complex termination circuitry simultaneously active, the segmented architecture enables selective activation, reducing overall system complexity while maintaining adaptability.

Inventive Principle:
Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution dynamically maintains the CAN bus's termination state, restoring performance in real-time even when terminating nodes are lost, thereby improving signal quality and electromagnetic compatibility.

Implementation Method 1

measuring, by a device operatively coupled to a processor, an impedance of a controller area network (CAN) bus

Methodology Applied
Scientific EffectImpedance measurement: Electrical Resistance

Data Source

PatentEP4109825B1Smart controller area network termination
Publication Date: 2024.12.04 VOLVO CAR CORP
  • EP4109825B1 patent drawingFigure 1
  • EP4109825B1 patent drawingFigure 2
  • EP4109825B1 patent drawingFigure 3

AI summary

Systems and techniques that facilitate smart CAN termination are provided. In various embodiments, a system can comprise a sensor component that can measure an impedance of a controller area network (CAN) bus. In various aspects, the system can further comprise a termination component that can convert at least one node of the CAN bus from a non-terminating state to a terminating state, based on the impedance.