Real-time room occupancy estimation with Bayesian machine learning using a single PIR sensor and microcontroller. Leech, C., Raykov, Y. P., Ozer, E., & Merrett, G. V. In 2017 IEEE Sensors Applications Symposium (SAS), pages 1–6, March, 2017.
Real-time room occupancy estimation with Bayesian machine learning using a single PIR sensor and microcontroller [link]Paper  doi  abstract   bibtex   
This paper presents the implementation and deployment of a compute/memory intensive non-parametric Bayesian machine learning algorithm on a microcontroller unit (MCU) to estimate room occupancy in a Smart Room using a single analogue PIR sensor. We envisage an IoT device consisting of a resource-constrained MCU, PIR sensor and a battery running the occupancy estimation algorithm and operating over days or months without recharging or replacing the battery. Both hardware-independent and hardware-dependent optimizations are performed to reduce memory footprint and yet provide acceptable real-time performance while consuming less energy. We show a significant reduction in the on-chip memory usage in the MCUs by the algorithm through optimisation of the machine learning models and of the static memory footprint and dynamic memory usage. We also show that a low-end MCU does not meet the real-time requirements of the application without causing high average power consumption. However, a moderately high-performance MCU with a higher clock frequency and hardware floating-point unit provides 19x improvement in the execution time of the algorithm, better meeting the real-time specification of the application and reducing power consumption. Further, we estimate the battery lifetime of the IoT device if it operates continuously in a Smart Room. With a typical size battery, an IoT device consisting of a Cortex-M4F MCU and PIR sensor can operate for more than a month without replacement or recharging of the battery while running the compute-intensive Bayesian machine learning algorithm.
@inproceedings{leech_real-time_2017,
	title = {Real-time room occupancy estimation with {Bayesian} machine learning using a single {PIR} sensor and microcontroller},
	url = {https://ieeexplore.ieee.org/document/7894091},
	doi = {10.1109/SAS.2017.7894091},
	abstract = {This paper presents the implementation and deployment of a compute/memory intensive non-parametric Bayesian machine learning algorithm on a microcontroller unit (MCU) to estimate room occupancy in a Smart Room using a single analogue PIR sensor. We envisage an IoT device consisting of a resource-constrained MCU, PIR sensor and a battery running the occupancy estimation algorithm and operating over days or months without recharging or replacing the battery. Both hardware-independent and hardware-dependent optimizations are performed to reduce memory footprint and yet provide acceptable real-time performance while consuming less energy. We show a significant reduction in the on-chip memory usage in the MCUs by the algorithm through optimisation of the machine learning models and of the static memory footprint and dynamic memory usage. We also show that a low-end MCU does not meet the real-time requirements of the application without causing high average power consumption. However, a moderately high-performance MCU with a higher clock frequency and hardware floating-point unit provides 19x improvement in the execution time of the algorithm, better meeting the real-time specification of the application and reducing power consumption. Further, we estimate the battery lifetime of the IoT device if it operates continuously in a Smart Room. With a typical size battery, an IoT device consisting of a Cortex-M4F MCU and PIR sensor can operate for more than a month without replacement or recharging of the battery while running the compute-intensive Bayesian machine learning algorithm.},
	urldate = {2024-05-06},
	booktitle = {2017 {IEEE} {Sensors} {Applications} {Symposium} ({SAS})},
	author = {Leech, Charles and Raykov, Yordan P. and Ozer, Emre and Merrett, Geoff V.},
	month = mar,
	year = {2017},
	keywords = {Batteries, Bayes methods, Estimation, Hidden Markov models, MATLAB, Optimization, Standards},
	pages = {1--6},
}

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