二维无迹卡尔曼滤波 python
时间: 2023-08-23 09:04:42 浏览: 94
无迹卡尔曼滤波
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以下是一个简单的二维无迹卡尔曼滤波的Python实现:
```python
import numpy as np
def unscented_kalman_filter(x, P, z, Q, R, h, f):
n = len(x)
m = len(z)
alpha = 0.001
kappa = 0
beta = 2
lamda = alpha**2 * (n + kappa) - n
# Generate sigma points
X = np.zeros((n, 2 * n + 1))
X[:,0] = x
S = np.linalg.cholesky((n + lamda) * P)
for i in range(n):
X[:,i+1] = x + S[:,i]
X[:,i+1+n] = x - S[:,i]
# Propagate sigma points through f
Y = np.zeros((m, 2 * n + 1))
for i in range(2 * n + 1):
Y[:,i] = h(X[:,i])
# Calculate predicted measurements and covariance
z_hat = np.sum(Y, axis=1) / (2 * n + 1)
Pzz = R
for i in range(2 * n + 1):
Pzz += beta * np.outer(Y[:,i] - z_hat, Y[:,i] - z_hat) / (2 * n + beta)
# Calculate cross-covariance
Pxz = np.zeros((n, m))
for i in range(2 * n + 1):
Pxz += beta * np.outer(X[:,i] - x, Y[:,i] - z_hat) / (2 * n + beta)
# Calculate Kalman gain
K = Pxz @ np.linalg.inv(Pzz)
# Update state and covariance
x = x + K @ (z - z_hat)
P = P - K @ Pzz @ K.T + Q
return x, P
```
其中,x和P是状态向量和协方差矩阵,z是测量向量,Q和R是过程噪声和测量噪声的协方差矩阵,h和f是非线性函数,用于计算测量向量和状态转移。该函数返回更新后的状态向量和协方差矩阵。
该实现中使用了默认参数值的标准设置,其中alpha、kappa、beta、lamda分别是无迹变换中的参数。这些参数的具体含义和如何选择可以参考文献。
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