WPILibC++  unspecified
LinearDigitalFilter.h
1 /*----------------------------------------------------------------------------*/
2 /* Copyright (c) 2015-2018 FIRST. 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 <memory>
11 #include <vector>
12 
13 #include <llvm/ArrayRef.h>
14 
15 #include "Filter.h"
16 #include "circular_buffer.h"
17 
18 namespace frc {
19 
70 class LinearDigitalFilter : public Filter {
71  public:
73  llvm::ArrayRef<double> fbGains);
74  LinearDigitalFilter(std::shared_ptr<PIDSource> source,
75  llvm::ArrayRef<double> ffGains,
76  llvm::ArrayRef<double> fbGains);
77 
78  // Static methods to create commonly used filters
80  double timeConstant, double period);
81  static LinearDigitalFilter HighPass(PIDSource& source, double timeConstant,
82  double period);
83  static LinearDigitalFilter MovingAverage(PIDSource& source, int taps);
84  static LinearDigitalFilter SinglePoleIIR(std::shared_ptr<PIDSource> source,
85  double timeConstant, double period);
86  static LinearDigitalFilter HighPass(std::shared_ptr<PIDSource> source,
87  double timeConstant, double period);
88  static LinearDigitalFilter MovingAverage(std::shared_ptr<PIDSource> source,
89  int taps);
90 
91  // Filter interface
92  double Get() const override;
93  void Reset() override;
94 
95  // PIDSource interface
96  double PIDGet() override;
97 
98  private:
99  circular_buffer<double> m_inputs;
100  circular_buffer<double> m_outputs;
101  std::vector<double> m_inputGains;
102  std::vector<double> m_outputGains;
103 };
104 
105 } // namespace frc
Definition: RobotController.cpp:14
LinearDigitalFilter(PIDSource &source, llvm::ArrayRef< double > ffGains, llvm::ArrayRef< double > fbGains)
Create a linear FIR or IIR filter.
Definition: LinearDigitalFilter.cpp:22
PIDSource interface is a generic sensor source for the PID class.
Definition: PIDSource.h:20
static LinearDigitalFilter MovingAverage(PIDSource &source, int taps)
Creates a K-tap FIR moving average filter of the form: y[n] = 1/k * (x[k] + x[k-1] + … + x[0]) ...
Definition: LinearDigitalFilter.cpp:93
double PIDGet() override
Calculates the next value of the filter.
Definition: LinearDigitalFilter.cpp:177
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory)...
Definition: ArrayRef.h:32
static LinearDigitalFilter HighPass(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...
Definition: LinearDigitalFilter.cpp:76
void Reset() override
Reset the filter state.
Definition: LinearDigitalFilter.cpp:167
double Get() const override
Returns the current filter estimate without also inserting new data as PIDGet() would do...
Definition: LinearDigitalFilter.cpp:153
This class implements a linear, digital filter.
Definition: LinearDigitalFilter.h:70
Interface for filters.
Definition: Filter.h:19
static LinearDigitalFilter SinglePoleIIR(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 ...
Definition: LinearDigitalFilter.cpp:58