A conversation with a flat-earth believer inspired Bertrand Selva to create a device that measures the Earth’s rotation using two gyroscopes. This innovative apparatus offers a compact alternative to traditional methods, such as the Foucault pendulum, demonstrating the planet’s rotation in real-time.
The device is built around BMI160 MEMS gyroscopes, which feature a least significant bit for angular velocity of 0.0038 degrees per second. In comparison, the Earth rotates at approximately 0.00416 degrees per second. To accurately detect this subtle movement, the system takes measurements from the sensors positioned in four different orientations. This approach helps to minimize the sensor bias and the influence of gravitational effects.
Prior to conducting tests, Selva meticulously oriented the sensors toward true north. A stepper motor then cycled the sensors through the four positions, while a Raspberry Pi Pico recorded 128 measurements at each position. The cycle could run as many as 200 times, and as the number of cycles increased, the error margin tended to decrease.
To process the raw data effectively, Selva employed a Kalman filter, which successfully extracted the rotational signal. Remarkably, the measurements came within two percent of the true rotational velocity of the Earth. During his experiments, Selva discovered that the accuracy of the readings was significantly influenced by the system’s alignment with true north, to the extent that it could function as a compass.
Despite the impressive results, Selva’s demonstration did not sway his neighbor’s beliefs about the Earth being flat. Nonetheless, the project stands as a notable achievement in the realm of physics and engineering.
This gyroscope-based system represents a simpler method for measuring Earth’s rotation, but it is worth noting that for higher precision, various standards organizations have established more complex methods for conducting these measurements. Interestingly, it is also possible to measure Earth’s rotation using a gaming console, such as a PlayStation, showcasing the versatility of modern technology in scientific exploration.
