Package edu.wpi.first.math.controller
Class LinearPlantInversionFeedforward<States extends Num,Inputs extends Num,Outputs extends Num>
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- edu.wpi.first.math.controller.LinearPlantInversionFeedforward<States,Inputs,Outputs>
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public class LinearPlantInversionFeedforward<States extends Num,Inputs extends Num,Outputs extends Num> extends Object
Constructs a plant inversion model-based feedforward from aLinearSystem
.The feedforward is calculated as u_ff = B+ (r_k+1 - A r_k) , where B+ is the pseudoinverse of B.
For more on the underlying math, read https://file.tavsys.net/control/controls-engineering-in-frc.pdf.
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Constructor Summary
Constructors Constructor Description LinearPlantInversionFeedforward(Matrix<States,States> A, Matrix<States,Inputs> B, double dtSeconds)
Constructs a feedforward with the given coefficients.LinearPlantInversionFeedforward(LinearSystem<States,Inputs,Outputs> plant, double dtSeconds)
Constructs a feedforward with the given plant.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description Matrix<Inputs,N1>
calculate(Matrix<States,N1> nextR)
Calculate the feedforward with only the desired future reference.Matrix<Inputs,N1>
calculate(Matrix<States,N1> r, Matrix<States,N1> nextR)
Calculate the feedforward with current and future reference vectors.Matrix<States,N1>
getR()
Returns the current reference vector r.double
getR(int row)
Returns an element of the current reference vector r.Matrix<Inputs,N1>
getUff()
Returns the previously calculated feedforward as an input vector.double
getUff(int row)
Returns an element of the previously calculated feedforward.void
reset()
Resets the feedforward with a zero initial state vector.void
reset(Matrix<States,N1> initialState)
Resets the feedforward with a specified initial state vector.
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Constructor Detail
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LinearPlantInversionFeedforward
public LinearPlantInversionFeedforward(LinearSystem<States,Inputs,Outputs> plant, double dtSeconds)
Constructs a feedforward with the given plant.- Parameters:
plant
- The plant being controlled.dtSeconds
- Discretization timestep.
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LinearPlantInversionFeedforward
public LinearPlantInversionFeedforward(Matrix<States,States> A, Matrix<States,Inputs> B, double dtSeconds)
Constructs a feedforward with the given coefficients.- Parameters:
A
- Continuous system matrix of the plant being controlled.B
- Continuous input matrix of the plant being controlled.dtSeconds
- Discretization timestep.
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Method Detail
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getUff
public Matrix<Inputs,N1> getUff()
Returns the previously calculated feedforward as an input vector.- Returns:
- The calculated feedforward.
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getUff
public double getUff(int row)
Returns an element of the previously calculated feedforward.- Parameters:
row
- Row of uff.- Returns:
- The row of the calculated feedforward.
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getR
public Matrix<States,N1> getR()
Returns the current reference vector r.- Returns:
- The current reference vector.
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getR
public double getR(int row)
Returns an element of the current reference vector r.- Parameters:
row
- Row of r.- Returns:
- The row of the current reference vector.
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reset
public void reset(Matrix<States,N1> initialState)
Resets the feedforward with a specified initial state vector.- Parameters:
initialState
- The initial state vector.
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reset
public void reset()
Resets the feedforward with a zero initial state vector.
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calculate
public Matrix<Inputs,N1> calculate(Matrix<States,N1> nextR)
Calculate the feedforward with only the desired future reference. This uses the internally stored "current" reference.If this method is used the initial state of the system is the one set using
reset(Matrix)
. If the initial state is not set it defaults to a zero vector.- Parameters:
nextR
- The reference state of the future timestep (k + dt).- Returns:
- The calculated feedforward.
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calculate
public Matrix<Inputs,N1> calculate(Matrix<States,N1> r, Matrix<States,N1> nextR)
Calculate the feedforward with current and future reference vectors.- Parameters:
r
- The reference state of the current timestep (k).nextR
- The reference state of the future timestep (k + dt).- Returns:
- The calculated feedforward.
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