Presentation Information
[B-15-40]Power Saving of Sensor Nodes in Seat Occupancy Visualization System
〇Mio Kobayashi1 (1. Shinshu University)
Keywords:
vibration sensor,power saving,leak current,sensor nodes
[Objective] This study aims to reduce the power consumption of a seat occupancy visualization system designed for a library study space to achieve long-term deployment. While our previous system operated for 15 days using a 300-mAh Li-Po battery, further power optimization was required to reduce maintenance costs.
[Methods] The system comprises sensor nodes (ESP32-C3, MPU6050) and a gateway (GW). Nodes maintain an event-driven deep-sleep mode and transmit occupancy data via ESP-NOW only upon detecting vibration. To extend battery life, we analyzed the node's standby current using a high-precision current logger.
[Results] Waveform analysis revealed a sink-direction parasitic leak current flowing into the microcontroller's A0 pin from two 1-MΩ voltage-divider resistors used for battery monitoring. This leak increased the average standby current to 1.5 mA. To block this pathway, we software-disabled the A0 pin during sleep mode. Combined with intermittent operation of the vibration sensor, the standby current was successfully reduced to under 300 μA.
[Conclusion] This approach extended the calculated operation time from 15 to approximately 75 days. Future work includes full-seat deployment to evaluate long-term system stability.
[Methods] The system comprises sensor nodes (ESP32-C3, MPU6050) and a gateway (GW). Nodes maintain an event-driven deep-sleep mode and transmit occupancy data via ESP-NOW only upon detecting vibration. To extend battery life, we analyzed the node's standby current using a high-precision current logger.
[Results] Waveform analysis revealed a sink-direction parasitic leak current flowing into the microcontroller's A0 pin from two 1-MΩ voltage-divider resistors used for battery monitoring. This leak increased the average standby current to 1.5 mA. To block this pathway, we software-disabled the A0 pin during sleep mode. Combined with intermittent operation of the vibration sensor, the standby current was successfully reduced to under 300 μA.
[Conclusion] This approach extended the calculated operation time from 15 to approximately 75 days. Future work includes full-seat deployment to evaluate long-term system stability.