预处理数据
R2026a删除均值、偏移量和线性趋势；重新构造缺失数据，更改数据采样率
System Identification Toolbox™ 和命令行函数允许您在将估计（和验证）数据用于模型估计之前对其进行预处理。预处理有助于优化数据，并更正或消除不准确之处。它用来确保数据处于适合模型估计的形式。
选择用于估计的数据后，请检查数据中是否存在类似下面这些不需要的特征：
缺失值或错误值（也称为 outliers）。例如，您可能会发现空缺数据（表明数据缺失）、与其余数据不符的值，或无信息的值。
信号电平的偏移与漂移（低频干扰）。
高于系统动态特性所关注频率区间的高频干扰。
根据数据的特征，您可以对缺失数据进行重建，调整数据采样率，或从数据中去除均值、常数偏移量或线性趋势。
有关分析时域或频域数据的方法，请参阅How to Analyze Data Using the advice Command。
函数
detrend | Subtract offset or trend from time-domain signals contained in
iddata objects |
retrend | 向存储在 iddata 对象中的时域数据信号添加偏移量或趋势 |
diff | Iddata 对象中的差异信号 |
idfilt | Filter data using user-defined passbands, general filters, or Butterworth filters |
misdata | Reconstruct missing input and output data |
nkshift | Shift data sequences |
idresamp | Resample time-domain data by decimation or interpolation |
idresampOptions | Option set for idresamp (自 R2023a 起) |
resample | （不建议）通过降采样或插值对存储在 iddata 对象中的时域数据进行重采样（需要 Signal Processing Toolbox 软件） |
getTrend | Create trend information object to store offset, mean, and trend information for
time-domain signals stored in iddata object |
chgFreqUnit | Change frequency units of frequency-response data model |
fdel | 从频率响应数据 (FRD) 模型中删除指定数据 |
TrendInfo | Offset and linear trend slope values for detrending data |
主题
数据的处理、重采样和滤波
- Handling Missing Data and Outliers
Handling missing or erroneous data values. - Handling Offsets and Trends in Data
Removing and restoring constant offsets and linear trends in data signals. - Resampling Data
Decimating and interpolating (resampling) data. - Filtering Data
Deciding whether to filter data before model estimation and how to prefilter data.
使用 App 对数据进行预处理
- 使用快速入门预处理数据
从数据中减去平均值，并指定估计数据和验证数据。 - How to Detrend Data Using the App
Before you can perform this task, you must have regularly-sampled, steady-state time-domain data imported into the System Identification app. - Resampling Data Using the App
Use the System Identification app to resample time-domain data. - How to Filter Data Using the App
The System Identification app lets you filter time-domain data using a fifth-order Butterworth filter by enhancing or selecting specific passbands.
使用命令行对数据进行预处理
- How to Detrend Data at the Command Line
Before you can perform this task, you must have time-domain data as aniddataobject. - Resampling Data at the Command Line
Decimate and interpolate time-domain data. - How to Filter Data at the Command Line
Useidfiltto apply passband and other custom filters to a time-domain or a frequency-domainiddataobject.
