Daisy Chain Sensor Switching Fault Isolation
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Solution Overview
Problem
In daisy chain topologies used for sensor activation, a permanently closed switch in one sensor can cause the entire chain to malfunction, leading to unnecessary shutdown and loss of operational availability, as the defective sensor disrupts the power supply to downstream sensors.
Innovation Solution
A method is introduced where an upstream sensor monitors the initialization of a downstream sensor for faults such as excessive quiescent current, bus capacitance, or Manchester error rates, and if a fault is detected, a suppression signal is sent to prevent the upstream sensor from closing its switch, thereby isolating the defective sensor and allowing the rest of the chain to operate with maximum availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sensor with a permanently closed switch is included in the daisy chain, then the sensor can be initialized and contribute data, but the defective sensor disrupts power supply to downstream sensors causing complete chain shutdown
Solution Approach 1:
The patent divides the sensor chain into independent operational segments by introducing monitoring switches that can individually isolate defective sensors. Each sensor is equipped with a monitoring switch that can open to disconnect downstream sensors from power when a fault is detected, allowing upstream sensors to continue operating independently.
Solution Approach 2:
The patent introduces monitoring switches as intermediary components between sensors in the daisy chain. These switches act as mediators that can block the harmful effect of a permanently closed switch by opening the circuit downstream, while still allowing the defective sensor itself to remain initialized and functional.
2Object-affected harmful factors
If the entire daisy chain is shut off due to a defective sensor, then the harmful effect is eliminated, but all sensors including functional ones lose operational availability
Solution Approach 1:
The system segments the power distribution control by introducing individual monitoring switches for each sensor position. This allows selective isolation of only the defective sensor's downstream portion while maintaining power supply to upstream functional sensors, rather than shutting off the entire chain.
Solution Approach 2:
The patent applies local quality control by implementing fault isolation at the specific location of the defective sensor. The monitoring switch associated with each sensor can locally open the circuit only when that specific sensor is defective, preserving the operational status of other sensors with different local conditions.
3Reliability
If monitoring and suppression signals are added to detect and isolate defective sensors, then sensor chain availability is improved, but device complexity increases
Solution Approach 1:
The monitoring switches serve multiple functions: they act as normal power distribution switches during initialization, serve as fault detection indicators, and function as isolation mechanisms. This multi-functionality reduces the need for separate dedicated components for each function, thereby limiting the increase in overall device complexity.
Solution Approach 2:
Each sensor in the daisy chain is equipped with its own monitoring switch that can autonomously detect faults and isolate downstream sensors without requiring external intervention. The system self-manages fault detection and isolation, reducing the need for complex external control mechanisms.
Data Source
AI summary
A method for commissioning a sensor series circuit configured in a daisy chain topology. A second sensor being downstream from a first sensor. The method includes furnishing a first switch signal to the first sensor to close the first switch, the first switch signal being furnished in response to a successful initialization of the first sensor, monitoring a function of the second sensor during initialization of the second sensor to ascertain whether the second sensor exhibits a fault upon initialization or is initialized correctly, and to furnish a fault signal if it is ascertained that the second sensor exhibits a fault upon initialization; and outputting a suppression signal to the first sensor if the fault signal has been furnished, to prevent the first switch from being closed.