Wireless Sensor Node Power Reduction via Predictive Sleep Control
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Solution Overview
Problem
Wireless process control systems face challenges in balancing data transfer reliability and power consumption, particularly due to high traffic loads that shorten battery life and the need for frequent synchronization messages, which increase costs and material expenses.
Innovation Solution
A method that predicts when sensor measurement data is needed, allowing sensor nodes to enter a sleep mode and communicate only during dedicated time slots, reducing power consumption and extending battery life by minimizing unnecessary communication occasions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If equidistant sampling and periodical transmission are used to ensure data transfer reliability, then data transfer reliability is improved, but traffic load increases and battery life is shortened
Solution Approach 1:
The patent implements dynamic sampling where the sampling rate is adjusted based on process conditions. During steady-state operation, sampling is reduced to minimize traffic load and power consumption. During transient states or when quality indicators indicate poor data quality, sampling frequency increases to maintain reliability. This dynamic adaptation resolves the contradiction by making the system flexible rather than fixed.
Solution Approach 2:
The system changes key parameters including sampling rate, prediction horizon, and quality thresholds based on operating conditions. By dynamically adjusting these parameters, the system optimizes the balance between data transfer reliability and power consumption, allowing equidistant sampling to be replaced with adaptive sampling that maintains reliability while reducing energy use.
2Measurement precision
If frequent synchronization messages are sent to maintain accurate time stamps, then measurement precision is improved, but traffic load increases and power consumption increases
Solution Approach 1:
The system performs preliminary actions by establishing synchronization protocols and time stamping mechanisms in advance. Once synchronized, the system maintains timing accuracy without requiring frequent re-synchronization messages. The prediction mechanism is also prepared in advance, allowing the system to anticipate when data will be needed and reduce unnecessary communication.
Solution Approach 2:
The system uses feedback from quality indicators and process state monitoring to adjust synchronization frequency. When the system is stable and predictions are accurate, synchronization messages are reduced. When quality deteriorates or unexpected changes occur, synchronization frequency increases to maintain time stamp accuracy, thus optimizing power consumption while preserving measurement precision.
3Reliability
If equidistant sampling is used during steady state, then data transfer reliability is maintained, but traffic load is unnecessarily high when no control action is needed
Solution Approach 1:
The patent implements dynamic sampling that adapts to system state. During steady-state operation where no control action is needed, the sampling rate is automatically reduced based on prediction accuracy and quality indicators. When transient conditions occur or control actions are required, sampling rate increases to maintain reliability. This resolves the contradiction by making communication efficient rather than uniformly active.
Solution Approach 2:
The system extracts and removes unnecessary data transmissions during steady-state operation. By using prediction mechanisms to identify when data will not contribute to control decisions, the system eliminates redundant communications while maintaining reliability for meaningful data, thus improving communication efficiency without sacrificing essential data transfer reliability.
Data Source
AI summary
A method in a wireless process control system for reducing power consumption of a sensor node of the wireless process control system. The wireless process control system further includes a controller in wireless communication with the sensor node wherein the sensor node is in a sleep mode. The method includes the steps of: predicting based on an error signal, when sensor measurement data is needed from the sensor node and determining an instant of time for communication between the controller and the sensor node based thereon; and the sensor node re-entering the sleep mode. The invention also relates to computer program products and a controller.