How IMUs Work

This page will be focused on explaining how each of the components on IMU works, disenchanting these delicate electronics.

Accelerometer:

Basic Idea

You can imagine the internal of an accelerometer to be two pieces of conductive metals attached to springs while leaving a dielectric gap between them.
The combination of two metallic plates leaves a dielectric gap that forms a classic capacitor100%

With the area A and permittivity ϵ known, capacitance C measured, we could calculate the distance between the plates d
Since the plates are attached to a spring, we can know the force F applied to the spring by formula F = k (Δd)
By Newton’s second law, F = ma, the acceleration of the object is calculated

In Reality

There are multiple metallic beams (shown in green), and a big moveable metal in all three directions (shown in red) that is attached to springs
This design allows the measurement of the capacitances on three axes to happen at once

this whole thing is smaller than the diameter of a human hair