SaM - Capacitive Accelerometer

• We take the primary sensor mass spring damper and we think of a fixed frame, as we have seen for strain gauges.
  • $M_s$ : sismic mass.
  • $K$ : spring coefficient.
  • $\lambda$ : damper coefficient.
  • $A(s)=\mathcal{L}[a(t)]$, where $a(t)$: acceleration
  • $R(s)=\mathcal{L}[r(t)]$l, where $r(t)$: displacemente between the resting position of the sismic mass and actual positon.
  • $r_{\infty }=\frac{M_S}{K}{a}_0$ : obtaing by using the final value theorem:${\lim }_{s\to 0}s\cdot F(s)={\lim }_{t\to \infty }f(t)$In this case we are ander the hypotesis of a constant acceleration ($a_0$)
  • ${\alpha }_r$ : sensitivity
• In this case, I have a sensor, which can turn an acceleration into a variation of a capacitance.
• The capacitance value of capacitive accelerometer can calculated as:$C=\frac{C_0}{1+\alpha a_0}$Where:
  • $C_0$ is the capacitance value at rest.
  • $a_0$ is the value of the constant accerelation.
  • $\alpha$ is the sensitivity.

---

Memory Card

---