Estimating Ground Inclination Using Strain Sensors with Fourier Series Representation

Figure 5

(a) RMSE for different Fourier series harmonics $n,$ where the estimator is tuned for slow, fast, and the combined slow + fast walking speeds. No significant improvement is made for $n>8$. For $n=8,$ the speed invariant estimator has RMSE $1.5^{°}$ compared to $1.2^{°}$ for the estimators specially tuned for slow or fast walking. (b) Measured strain signal $\mathbf{s}$ (black) and its Fourier series approximation $\widehat{\mathbf{s}}$ (red), using $n=8$ harmonics.

(a)

(b)