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[wpimath] Remove discretizeAQTaylor() (#5562)

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It gives incorrect results. Any replacement should just be an
implementation detail of discretizeAQ().

Closes #5339.
This commit is contained in:
Tyler Veness
2023-08-23 10:47:32 -07:00
committed by GitHub
parent 7c20fa1b18
commit 8f3d6a1d4b
4 changed files with 0 additions and 364 deletions
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96
wpimath/src/test/native/cpp/system/DiscretizationTest.cpp
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@@ -114,102 +114,6 @@ TEST(DiscretizationTest, DiscretizeFastModelAQ) {
<< discQIntegrated;
}
// Test that the Taylor series discretization produces nearly identical results.
TEST(DiscretizationTest, DiscretizeSlowModelAQTaylor) {
frc::Matrixd<2, 2> contA{{0, 1}, {0, 0}};
frc::Matrixd<2, 2> contQ{{1, 0}, {0, 1}};
constexpr auto dt = 1_s;
frc::Matrixd<2, 2> discQTaylor;
frc::Matrixd<2, 2> discA;
frc::Matrixd<2, 2> discATaylor;
// Continuous Q should be positive semidefinite
Eigen::SelfAdjointEigenSolver<Eigen::MatrixXd> esCont{contQ,
Eigen::EigenvaluesOnly};
for (int i = 0; i < contQ.rows(); ++i) {
EXPECT_GE(esCont.eigenvalues()[i], 0);
}
// T
// Q_d = ∫ e^(Aτ) Q e^(Aᵀτ) dτ
// 0
frc::Matrixd<2, 2> discQIntegrated = frc::RungeKuttaTimeVarying<
std::function<frc::Matrixd<2, 2>(units::second_t,
const frc::Matrixd<2, 2>&)>,
frc::Matrixd<2, 2>>(
[&](units::second_t t, const frc::Matrixd<2, 2>&) {
return frc::Matrixd<2, 2>((contA * t.value()).exp() * contQ *
(contA.transpose() * t.value()).exp());
},
0_s, frc::Matrixd<2, 2>::Zero(), dt);
frc::DiscretizeA<2>(contA, dt, &discA);
frc::DiscretizeAQTaylor<2>(contA, contQ, dt, &discATaylor, &discQTaylor);
EXPECT_LT((discQIntegrated - discQTaylor).norm(), 1e-10)
<< "Expected these to be nearly equal:\ndiscQTaylor:\n"
<< discQTaylor << "\ndiscQIntegrated:\n"
<< discQIntegrated;
EXPECT_LT((discA - discATaylor).norm(), 1e-10);
// Discrete Q should be positive semidefinite
Eigen::SelfAdjointEigenSolver<Eigen::MatrixXd> esDisc{discQTaylor,
Eigen::EigenvaluesOnly};
for (int i = 0; i < discQTaylor.rows(); ++i) {
EXPECT_GE(esDisc.eigenvalues()[i], 0);
}
}
// Test that the Taylor series discretization produces nearly identical results.
TEST(DiscretizationTest, DiscretizeFastModelAQTaylor) {
frc::Matrixd<2, 2> contA{{0, 1}, {0, -1500}};
frc::Matrixd<2, 2> contQ{{0.0025, 0}, {0, 1}};
constexpr auto dt = 5_ms;
frc::Matrixd<2, 2> discQTaylor;
frc::Matrixd<2, 2> discA;
frc::Matrixd<2, 2> discATaylor;
// Continuous Q should be positive semidefinite
Eigen::SelfAdjointEigenSolver<Eigen::MatrixXd> esCont{contQ,
Eigen::EigenvaluesOnly};
for (int i = 0; i < contQ.rows(); ++i) {
EXPECT_GE(esCont.eigenvalues()[i], 0);
}
// T
// Q_d = ∫ e^(Aτ) Q e^(Aᵀτ) dτ
// 0
frc::Matrixd<2, 2> discQIntegrated = frc::RungeKuttaTimeVarying<
std::function<frc::Matrixd<2, 2>(units::second_t,
const frc::Matrixd<2, 2>&)>,
frc::Matrixd<2, 2>>(
[&](units::second_t t, const frc::Matrixd<2, 2>&) {
return frc::Matrixd<2, 2>((contA * t.value()).exp() * contQ *
(contA.transpose() * t.value()).exp());
},
0_s, frc::Matrixd<2, 2>::Zero(), dt);
frc::DiscretizeA<2>(contA, dt, &discA);
frc::DiscretizeAQTaylor<2>(contA, contQ, dt, &discATaylor, &discQTaylor);
EXPECT_LT((discQIntegrated - discQTaylor).norm(), 1e-3)
<< "Expected these to be nearly equal:\ndiscQTaylor:\n"
<< discQTaylor << "\ndiscQIntegrated:\n"
<< discQIntegrated;
EXPECT_LT((discA - discATaylor).norm(), 1e-10);
// Discrete Q should be positive semidefinite
Eigen::SelfAdjointEigenSolver<Eigen::MatrixXd> esDisc{discQTaylor,
Eigen::EigenvaluesOnly};
for (int i = 0; i < discQTaylor.rows(); ++i) {
EXPECT_GE(esDisc.eigenvalues()[i], 0);
}
}
// Test that DiscretizeR() works
TEST(DiscretizationTest, DiscretizeR) {
frc::Matrixd<2, 2> contR{{2.0, 0.0}, {0.0, 1.0}};