Project
| # | Title | Team Members | TA | Documents | Sponsor |
|---|---|---|---|---|---|
| 41 | A smart cup holder for tracking and reminding you of your water intake. |
Lawrence Cheng Shengyuan Wang |
Zhuoer Zhang | ||
| Problem Many people do not drink enough water throughout the day because they forget to drink regularly or have difficulty tracking how much water they have consumed. Although smart water bottles are available, they require users to replace their existing cups or bottles and can be relatively expensive. Phone-based reminder applications can notify users at fixed intervals, but they generally cannot determine whether the user actually drank water or how much water was consumed. This motivates the development of a portable hydration-tracking device that can work with a user’s existing cup. The device should automatically estimate water consumption, provide reminders when the user has not consumed enough water, and minimize false records caused by simply lifting, carrying, or shaking the cup. Solution We propose an adjustable smart cup base that attaches to the bottom of an existing cup and remains attached while the cup is moved. Unlike a separate weighing coaster, the device travels together with the cup and can be used on any suitable horizontal surface. The cup rests on an internal weighing platform connected to a load cell. An ESP32 continuously samples the load-cell output through an HX711 converter. Measurements taken while the cup is lifted, carried, or shaken are unstable or unloaded and are therefore ignored. After the cup is returned to a horizontal surface, the system compares the new stable weight with the previous accepted weight. A stable decrease greater than a predefined threshold is recorded as estimated water consumption. An increase is classified as a refill, while small changes are ignored as measurement noise. Because water has a density of approximately 1 g/mL, a decrease of 20 grams can be estimated as 20 mL of water consumed. A display on the base shows the daily hydration goal and estimated intake. The user can select sound, vibration, or silent visual reminders. An optional Bluetooth application can display drinking history and allow the user to configure the daily goal and reminder interval. Solution Components Weight Measurement and Mechanical Subsystem The base will be printed by 3D printing materials to be secure at the bottom of the cup. The cup rests on an upper weighing platform, while the lower enclosure contacts the supporting surface. A load cell placed between these two structures measures the combined weight of the cup and its contents. The mechanical design must ensure that the cup’s vertical load passes through the load cell. 2 kg single-point load cell HX711 load-cell amplifier and ADC Internal Weighing Platform Protective base enclosure Processing and Intake-Detection Subsystem The ESP32-S3 continuously receives weight samples from the HX711. A recent measurement is used to determine whether the cup is present and the reading is stable. A new weight is accepted only when its variation remains below a defined limit for approximately one second. The firmware then compares it with the previous stable measurement. Small weight change: ignored as noise Stable weight decrease: recorded as estimated consumption Stable weight increase: classified as a refill Unstable or unloaded reading: ignored Abnormally large change: classified as cup removal or measurement error This logic prevents lifting and shaking from being recorded because the measurements during these actions are unstable, and lifting without drinking produces approximately the same weight after the cup is returned. MCU: ESP32 Load-cell interface: HX711 Stability-detection and weight-comparison algorithm Bluetooth Low Energy for optional application communication User Interface and Reminder Subsystem A small display mounted on the side of the base shows the user’s daily hydration goal, estimated consumption, and remaining amount. The ESP32 tracks the time since the most recent confirmed weight-loss event and the user’s progress toward the daily goal. If the user has not consumed water for a configured period or falls behind the expected progress, the system activates the selected reminder mode. LED display Buzzer Vibration motor and driver Status LED Control buttons or reminder-mode switch Power Subsystem The device is powered by a rechargeable battery. A USB-C charging circuit charges the battery, while a regulated 3.3 V supply powers the ESP32, HX711, and display. Rechargeable battery USB-C charging circuit 3.3 V voltage regulator Power switch Decoupling capacitors Vibration-motor driver Success requires: Detecting water reductions between 20 and 300 mL with an error no greater than ±10 mL or ±10%. Correctly rejecting at least 90% of lift-and-return trials in which no water is removed. Correctly rejecting at least 90% of shaking and moving trials. Recognizing added water as a refill instead of consumption. Updating the daily total and remaining goal on the display. Operating for at least one normal day before recharging. Because the device uses only weight measurements, it cannot distinguish drinking from intentionally pouring water out. Therefore, the system records a confirmed reduction in water as estimated consumption. |
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