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LinearDigitalFilter.h
1 /*----------------------------------------------------------------------------*/
2 /* Copyright (c) FIRST 2015-2016. All Rights Reserved. */
3 /* Open Source Software - may be modified and shared by FRC teams. The code */
4 /* must be accompanied by the FIRST BSD license file in the root directory of */
5 /* the project. */
6 /*----------------------------------------------------------------------------*/
7 
8 #pragma once
9 
10 #include <initializer_list>
11 #include <memory>
12 #include <vector>
13 #include "Filter.h"
14 #include "CircularBuffer.h"
15 
65 class LinearDigitalFilter : public Filter {
66  public:
67  LinearDigitalFilter(std::shared_ptr<PIDSource> source,
68  std::initializer_list<double> ffGains,
69  std::initializer_list<double> fbGains);
70  LinearDigitalFilter(std::shared_ptr<PIDSource> source,
71  std::initializer_list<double> ffGains,
72  const std::vector<double>& fbGains);
73  LinearDigitalFilter(std::shared_ptr<PIDSource> source,
74  const std::vector<double>& ffGains,
75  std::initializer_list<double> fbGains);
76  LinearDigitalFilter(std::shared_ptr<PIDSource> source,
77  const std::vector<double>& ffGains,
78  const std::vector<double>& fbGains);
79 
80  // Static methods to create commonly used filters
81  static LinearDigitalFilter SinglePoleIIR(std::shared_ptr<PIDSource> source,
82  double timeConstant, double period);
83  static LinearDigitalFilter HighPass(std::shared_ptr<PIDSource> source,
84  double timeConstant, double period);
85  static LinearDigitalFilter MovingAverage(std::shared_ptr<PIDSource> source,
86  unsigned int taps);
87 
88  // Filter interface
89  double Get() const override;
90  void Reset() override;
91 
92  // PIDSource interface
93  double PIDGet() override;
94 
95  private:
96  CircularBuffer<double> m_inputs;
97  CircularBuffer<double> m_outputs;
98  std::vector<double> m_inputGains;
99  std::vector<double> m_outputGains;
100 };
static LinearDigitalFilter SinglePoleIIR(std::shared_ptr< PIDSource > source, double timeConstant, double period)
Creates a one-pole IIR low-pass filter of the form: y[n] = (1-gain)*x[n] + gain*y[n-1] where gain = e...
Definition: LinearDigitalFilter.cpp:75
LinearDigitalFilter(std::shared_ptr< PIDSource > source, std::initializer_list< double > ffGains, std::initializer_list< double > fbGains)
Create a linear FIR or IIR filter.
Definition: LinearDigitalFilter.cpp:19
Interface for filters.
Definition: Filter.h:16
static LinearDigitalFilter MovingAverage(std::shared_ptr< PIDSource > source, unsigned int taps)
Creates a K-tap FIR moving average filter of the form: y[n] = 1/k * (x[k] + x[k-1] + ...
Definition: LinearDigitalFilter.cpp:110
double Get() const override
Returns the current filter estimate without also inserting new data as PIDGet() would do...
Definition: LinearDigitalFilter.cpp:121
void Reset() override
Reset the filter state.
Definition: LinearDigitalFilter.cpp:138
static LinearDigitalFilter HighPass(std::shared_ptr< PIDSource > source, double timeConstant, double period)
Creates a first-order high-pass filter of the form: y[n] = gain*x[n] + (-gain)*x[n-1] + gain*y[n-1] w...
Definition: LinearDigitalFilter.cpp:93
double PIDGet() override
Calculates the next value of the filter.
Definition: LinearDigitalFilter.cpp:148
This class implements a linear, digital filter.
Definition: LinearDigitalFilter.h:65