Smart-home proxy devices with long-polling
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Solution Overview
Problem
Existing thermostats face challenges in providing advanced functionalities like powerful microprocessors and wireless communications without requiring a 'common' wire or line power, while also ensuring easy installation and battery power management, especially in homes without a direct wire from the system transformer.
Innovation Solution
A rechargeable battery-powered thermostat with a battery charging circuit that harvests power from the HVAC system, allowing it to operate in low-power and high-power modes, and maintain wireless communications with a cloud-based management server, enabling efficient data transfer and control of HVAC systems without the need for a 'common' wire.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a thermostat uses a powerful microprocessor and wireless communications for advanced functionalities, then processing capability and connectivity are improved, but power consumption increases
Solution Approach 1:
The thermostat dynamically adjusts its operational state by switching between sleep mode and active mode based on communication needs. The microprocessor enters sleep mode to conserve power when not actively communicating, and transitions to active mode when data transfer is required, thereby balancing advanced processing capabilities with reduced power consumption.
Solution Approach 2:
The system employs periodic long-polling communications instead of continuous data transmission. The thermostat periodically wakes from sleep mode to exchange data with the server, maintaining connectivity while minimizing power consumption by keeping the microprocessor and wireless module dormant between polling intervals.
2Loss of time
If the thermostat maintains continuous wireless communication with the server, then data transfer timeliness is improved, but battery life decreases
Solution Approach 1:
The thermostat implements long-polling with extended intervals between communication sessions. Instead of continuous communication, the device periodically wakes from sleep mode to poll the server for updates and send data, thereby maintaining data transfer functionality while significantly reducing battery consumption compared to continuous communication protocols.
Solution Approach 2:
The system uses asymmetric communication where the server initiates most communications during active periods, and the thermostat primarily listens during sleep mode. This self-service approach allows the thermostat to maintain connectivity without frequently waking the microprocessor, thereby extending battery life while ensuring timely data transfer when needed.
3Adaptability or versatility
If the thermostat harvests power from the HVAC system, then external power requirements are reduced, but available power for advanced features is limited
Solution Approach 1:
The thermostat dynamically manages power by switching between power harvesting mode and battery power mode. When HVAC power is available, the system uses it to charge the battery and power operations. When HVAC power is insufficient or unavailable, the system seamlessly transitions to battery power, thereby maintaining installation flexibility while ensuring adequate power for advanced features.
Solution Approach 2:
The system changes operational parameters based on power availability. When harvesting power from the HVAC system, the thermostat adjusts its communication frequency and microprocessor activity to match the limited power budget. When battery power is available, the system can operate with higher power consumption, enabling more frequent communications and longer active periods for advanced features.
4Use of energy by moving object
If the thermostat operates in sleep mode to conserve power, then energy consumption is reduced, but communication responsiveness decreases
Solution Approach 1:
The thermostat uses periodic long-polling where the server initiates communications at predetermined intervals. During sleep mode, the thermostat misses some communication opportunities, but the periodic nature of polling ensures that data is eventually transferred without requiring continuous microprocessor operation. This approach accepts occasional delays in exchange for significant power savings.
Solution Approach 2:
The system introduces an intermediary mechanism where the server maintains a buffer of pending communications and retransmits data when the thermostat wakes from sleep mode. This intermediary approach allows the thermostat to remain in low-power mode longer while ensuring that communication responsiveness is maintained through queued data transfer upon wake-up.
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 provides a thermostat with advanced processing capabilities and wireless connectivity, ensuring extended battery life and timely data transfer, while avoiding the need for a 'common' wire and minimizing installation costs by using power harvesting and efficient power management.
Implementation Method 1
a battery charging circuit configured to charge the rechargeable battery at least in part by harvesting power from an HVAC system
Data Source
AI summary
Methods and systems facilitate network communications between a wireless network-connected thermostat and a cloud-based management server in a manner that promotes reduced power usage and extended service life of an energy-storage device of the thermostat, while at the same time accomplishing timely data transfer between the thermostat and the cloud-based management server for suitable and time-appropriate control of an HVAC system. The thermostat further comprises powering circuitry configured to: extract electrical power from one or more HVAC control wires in a manner that does not require a “common” wire; supply electrical power for thermostat operation; recharge the energy-storage device (if needed) using any surplus extracted power; and discharge the energy-storage device to assist in supplying electrical power for thermostat operation during intervals in which the extracted power alone is insufficient for thermostat operation.