Wearable Computer With Temperature Distance Sensors

A wrist-worn computer with temperature and contactless LIDAR distance sensors, so the user can measure temperature and distances anywhere.

Rechargeable battery supplies the circuit; a regulator gives the controller and sensors a steady 5 V. The Temperature sensor measures the temperature that the system monitors or controls. The Raspberry Pi 4 runs Linux and the main program, handles the camera, networking and heavier processing such as image recognition.

The Raspberry Pi is a full computer with an operating system, so it can run Python, OpenCV and a web server. An Arduino is a microcontroller that is better for simple real-time control but cannot process images or run multiple programs.

LM35 gives an analog output of 10 mV per °C, so 250 mV means 25 °C. The controller reads it with the ADC and converts the value to degrees.

Backup time (hours) ≈ battery capacity (Ah) × voltage × 0.8 efficiency ÷ load power (W). For example, 12 V 7 Ah at 20 W gives about 3.3 hours.

The input section senses the real-world quantity, the Raspberry Pi 4 processes it according to the program, and the output section displays the result and drives the actuators. The power supply section feeds every block.

A single-wire digital protocol for the temperature sensor and analog inputs read by the ADC for the analog sensors. Each protocol was chosen because the module supports it and it uses the fewest pins.

The controller and most sensors work at 5 V (ESP boards and some modules at 3.3 V). The battery powers the board, and a regulator steps it down. Motors and relays get their own supply line so they do not reset the controller.

Accuracy is how close a reading is to the true value. Precision is how close repeated readings are to each other. A sensor can be precise but inaccurate if it is not calibrated.