diff --git a/wpilibNewCommands/src/main/native/cpp/frc2/command/MecanumControllerCommand.cpp b/wpilibNewCommands/src/main/native/cpp/frc2/command/MecanumControllerCommand.cpp
index 902c26b30e..6059db4ece 100644
--- a/wpilibNewCommands/src/main/native/cpp/frc2/command/MecanumControllerCommand.cpp
+++ b/wpilibNewCommands/src/main/native/cpp/frc2/command/MecanumControllerCommand.cpp
@@ -6,7 +6,12 @@
 
 #include <utility>
 
+#include <units/velocity.h>
+#include <units/voltage.h>
+
 using namespace frc2;
+using kv_unit = units::compound_unit<units::volts,
+                                     units::inverse<units::meters_per_second>>;
 
 MecanumControllerCommand::MecanumControllerCommand(
     frc::Trajectory trajectory, std::function<frc::Pose2d()> pose,
@@ -95,6 +100,7 @@ MecanumControllerCommand::MecanumControllerCommand(
     Requirements requirements)
     : m_trajectory(std::move(trajectory)),
       m_pose(std::move(pose)),
+      m_feedforward(0_V, units::unit_t<kv_unit>{0}),
       m_kinematics(kinematics),
       m_controller(xController, yController, thetaController),
       m_desiredRotation(std::move(desiredRotation)),
@@ -116,6 +122,7 @@ MecanumControllerCommand::MecanumControllerCommand(
     Requirements requirements)
     : m_trajectory(std::move(trajectory)),
       m_pose(std::move(pose)),
+      m_feedforward(0_V, units::unit_t<kv_unit>{0}),
       m_kinematics(kinematics),
       m_controller(xController, yController, thetaController),
       m_maxWheelVelocity(maxWheelVelocity),
diff --git a/wpilibNewCommands/src/main/native/cpp/frc2/command/RamseteCommand.cpp b/wpilibNewCommands/src/main/native/cpp/frc2/command/RamseteCommand.cpp
index 91459858dd..b78b6ad4c1 100644
--- a/wpilibNewCommands/src/main/native/cpp/frc2/command/RamseteCommand.cpp
+++ b/wpilibNewCommands/src/main/native/cpp/frc2/command/RamseteCommand.cpp
@@ -6,9 +6,13 @@
 
 #include <utility>
 
+#include <units/velocity.h>
+#include <units/voltage.h>
 #include <wpi/sendable/SendableBuilder.h>
 
 using namespace frc2;
+using kv_unit = units::compound_unit<units::volts,
+                                     units::inverse<units::meters_per_second>>;
 
 RamseteCommand::RamseteCommand(
     frc::Trajectory trajectory, std::function<frc::Pose2d()> pose,
@@ -42,6 +46,7 @@ RamseteCommand::RamseteCommand(
     : m_trajectory(std::move(trajectory)),
       m_pose(std::move(pose)),
       m_controller(controller),
+      m_feedforward(0_V, units::unit_t<kv_unit>{0}),
       m_kinematics(std::move(kinematics)),
       m_outputVel(std::move(output)),
       m_usePID(false) {
diff --git a/wpimath/src/main/java/edu/wpi/first/math/controller/ArmFeedforward.java b/wpimath/src/main/java/edu/wpi/first/math/controller/ArmFeedforward.java
index 8c53f61958..e7551a762b 100644
--- a/wpimath/src/main/java/edu/wpi/first/math/controller/ArmFeedforward.java
+++ b/wpimath/src/main/java/edu/wpi/first/math/controller/ArmFeedforward.java
@@ -28,12 +28,20 @@ public class ArmFeedforward {
    * @param kg The gravity gain.
    * @param kv The velocity gain.
    * @param ka The acceleration gain.
+   * @throws IllegalArgumentException for kv &lt; zero.
+   * @throws IllegalArgumentException for ka &lt; zero.
    */
   public ArmFeedforward(double ks, double kg, double kv, double ka) {
     this.ks = ks;
     this.kg = kg;
     this.kv = kv;
     this.ka = ka;
+    if (kv < 0.0) {
+      throw new IllegalArgumentException("kv must be a non-negative number, got " + kv + "!");
+    }
+    if (ka < 0.0) {
+      throw new IllegalArgumentException("ka must be a non-negative number, got " + kv + "!");
+    }
   }
 
   /**
diff --git a/wpimath/src/main/java/edu/wpi/first/math/controller/ElevatorFeedforward.java b/wpimath/src/main/java/edu/wpi/first/math/controller/ElevatorFeedforward.java
index b7986caedf..9ae8135858 100644
--- a/wpimath/src/main/java/edu/wpi/first/math/controller/ElevatorFeedforward.java
+++ b/wpimath/src/main/java/edu/wpi/first/math/controller/ElevatorFeedforward.java
@@ -31,12 +31,20 @@ public class ElevatorFeedforward {
    * @param kg The gravity gain.
    * @param kv The velocity gain.
    * @param ka The acceleration gain.
+   * @throws IllegalArgumentException for kv &lt; zero.
+   * @throws IllegalArgumentException for ka &lt; zero.
    */
   public ElevatorFeedforward(double ks, double kg, double kv, double ka) {
     this.ks = ks;
     this.kg = kg;
     this.kv = kv;
     this.ka = ka;
+    if (kv < 0.0) {
+      throw new IllegalArgumentException("kv must be a non-negative number, got " + kv + "!");
+    }
+    if (ka < 0.0) {
+      throw new IllegalArgumentException("ka must be a non-negative number, got " + kv + "!");
+    }
   }
 
   /**
diff --git a/wpimath/src/main/java/edu/wpi/first/math/controller/SimpleMotorFeedforward.java b/wpimath/src/main/java/edu/wpi/first/math/controller/SimpleMotorFeedforward.java
index 63ceb8fa8f..f19e836617 100644
--- a/wpimath/src/main/java/edu/wpi/first/math/controller/SimpleMotorFeedforward.java
+++ b/wpimath/src/main/java/edu/wpi/first/math/controller/SimpleMotorFeedforward.java
@@ -21,11 +21,19 @@ public class SimpleMotorFeedforward {
    * @param ks The static gain.
    * @param kv The velocity gain.
    * @param ka The acceleration gain.
+   * @throws IllegalArgumentException for kv &lt; zero.
+   * @throws IllegalArgumentException for ka &lt; zero.
    */
   public SimpleMotorFeedforward(double ks, double kv, double ka) {
     this.ks = ks;
     this.kv = kv;
     this.ka = ka;
+    if (kv < 0.0) {
+      throw new IllegalArgumentException("kv must be a non-negative number, got " + kv + "!");
+    }
+    if (ka < 0.0) {
+      throw new IllegalArgumentException("ka must be a non-negative number, got " + kv + "!");
+    }
   }
 
   /**
diff --git a/wpimath/src/main/native/include/frc/controller/ArmFeedforward.h b/wpimath/src/main/native/include/frc/controller/ArmFeedforward.h
index 39f4f90e59..933a4051d6 100644
--- a/wpimath/src/main/native/include/frc/controller/ArmFeedforward.h
+++ b/wpimath/src/main/native/include/frc/controller/ArmFeedforward.h
@@ -11,6 +11,7 @@
 #include "units/angular_velocity.h"
 #include "units/math.h"
 #include "units/voltage.h"
+#include "wpimath/MathShared.h"
 
 namespace frc {
 /**
@@ -29,8 +30,6 @@ class WPILIB_DLLEXPORT ArmFeedforward {
   using ka_unit =
       units::compound_unit<units::volts, units::inverse<Acceleration>>;
 
-  constexpr ArmFeedforward() = default;
-
   /**
    * Creates a new ArmFeedforward with the specified gains.
    *
@@ -42,7 +41,20 @@ class WPILIB_DLLEXPORT ArmFeedforward {
   constexpr ArmFeedforward(
       units::volt_t kS, units::volt_t kG, units::unit_t<kv_unit> kV,
       units::unit_t<ka_unit> kA = units::unit_t<ka_unit>(0))
-      : kS(kS), kG(kG), kV(kV), kA(kA) {}
+      : kS(kS), kG(kG), kV(kV), kA(kA) {
+    if (kV.value() < 0) {
+      wpi::math::MathSharedStore::ReportError(
+          "kV must be a non-negative number, got {}!", kV.value());
+      kV = units::unit_t<kv_unit>{0};
+      wpi::math::MathSharedStore::ReportWarning("kV defaulted to 0.");
+    }
+    if (kA.value() < 0) {
+      wpi::math::MathSharedStore::ReportError(
+          "kA must be a non-negative number, got {}!", kA.value());
+      kA = units::unit_t<ka_unit>{0};
+      wpi::math::MathSharedStore::ReportWarning("kA defaulted to 0;");
+    }
+  }
 
   /**
    * Calculates the feedforward from the gains and setpoints.
@@ -163,10 +175,10 @@ class WPILIB_DLLEXPORT ArmFeedforward {
     return MaxAchievableAcceleration(-maxVoltage, angle, velocity);
   }
 
-  units::volt_t kS{0};
-  units::volt_t kG{0};
-  units::unit_t<kv_unit> kV{0};
-  units::unit_t<ka_unit> kA{0};
+  const units::volt_t kS;
+  const units::volt_t kG;
+  const units::unit_t<kv_unit> kV;
+  const units::unit_t<ka_unit> kA;
 };
 }  // namespace frc
 
diff --git a/wpimath/src/main/native/include/frc/controller/ElevatorFeedforward.h b/wpimath/src/main/native/include/frc/controller/ElevatorFeedforward.h
index 4d308f4ec7..2d81a0ae33 100644
--- a/wpimath/src/main/native/include/frc/controller/ElevatorFeedforward.h
+++ b/wpimath/src/main/native/include/frc/controller/ElevatorFeedforward.h
@@ -12,6 +12,7 @@
 #include "units/length.h"
 #include "units/time.h"
 #include "units/voltage.h"
+#include "wpimath/MathShared.h"
 
 namespace frc {
 /**
@@ -29,8 +30,6 @@ class ElevatorFeedforward {
   using ka_unit =
       units::compound_unit<units::volts, units::inverse<Acceleration>>;
 
-  ElevatorFeedforward() = default;
-
   /**
    * Creates a new ElevatorFeedforward with the specified gains.
    *
@@ -42,7 +41,20 @@ class ElevatorFeedforward {
   constexpr ElevatorFeedforward(
       units::volt_t kS, units::volt_t kG, units::unit_t<kv_unit> kV,
       units::unit_t<ka_unit> kA = units::unit_t<ka_unit>(0))
-      : kS(kS), kG(kG), kV(kV), kA(kA) {}
+      : kS(kS), kG(kG), kV(kV), kA(kA) {
+    if (kV.value() < 0) {
+      wpi::math::MathSharedStore::ReportError(
+          "kV must be a non-negative number, got {}!", kV.value());
+      kV = units::unit_t<kv_unit>{0};
+      wpi::math::MathSharedStore::ReportWarning("kV defaulted to 0.");
+    }
+    if (kA.value() < 0) {
+      wpi::math::MathSharedStore::ReportError(
+          "kA must be a non-negative number, got {}!", kA.value());
+      kA = units::unit_t<ka_unit>{0};
+      wpi::math::MathSharedStore::ReportWarning("kA defaulted to 0;");
+    }
+  }
 
   /**
    * Calculates the feedforward from the gains and setpoints.
@@ -170,10 +182,10 @@ class ElevatorFeedforward {
     return MaxAchievableAcceleration(-maxVoltage, velocity);
   }
 
-  units::volt_t kS{0};
-  units::volt_t kG{0};
-  units::unit_t<kv_unit> kV{0};
-  units::unit_t<ka_unit> kA{0};
+  const units::volt_t kS;
+  const units::volt_t kG;
+  const units::unit_t<kv_unit> kV;
+  const units::unit_t<ka_unit> kA;
 };
 }  // namespace frc
 
diff --git a/wpimath/src/main/native/include/frc/controller/SimpleMotorFeedforward.h b/wpimath/src/main/native/include/frc/controller/SimpleMotorFeedforward.h
index 86b40eab06..767b05d4d6 100644
--- a/wpimath/src/main/native/include/frc/controller/SimpleMotorFeedforward.h
+++ b/wpimath/src/main/native/include/frc/controller/SimpleMotorFeedforward.h
@@ -11,6 +11,7 @@
 #include "frc/system/plant/LinearSystemId.h"
 #include "units/time.h"
 #include "units/voltage.h"
+#include "wpimath/MathShared.h"
 
 namespace frc {
 /**
@@ -28,8 +29,6 @@ class SimpleMotorFeedforward {
   using ka_unit =
       units::compound_unit<units::volts, units::inverse<Acceleration>>;
 
-  constexpr SimpleMotorFeedforward() = default;
-
   /**
    * Creates a new SimpleMotorFeedforward with the specified gains.
    *
@@ -40,7 +39,20 @@ class SimpleMotorFeedforward {
   constexpr SimpleMotorFeedforward(
       units::volt_t kS, units::unit_t<kv_unit> kV,
       units::unit_t<ka_unit> kA = units::unit_t<ka_unit>(0))
-      : kS(kS), kV(kV), kA(kA) {}
+      : kS(kS), kV(kV), kA(kA) {
+    if (kV.value() < 0) {
+      wpi::math::MathSharedStore::ReportError(
+          "kV must be a non-negative number, got {}!", kV.value());
+      kV = units::unit_t<kv_unit>{0};
+      wpi::math::MathSharedStore::ReportWarning("kV defaulted to 0.");
+    }
+    if (kA.value() < 0) {
+      wpi::math::MathSharedStore::ReportError(
+          "kA must be a non-negative number, got {}!", kA.value());
+      kA = units::unit_t<ka_unit>{0};
+      wpi::math::MathSharedStore::ReportWarning("kA defaulted to 0;");
+    }
+  }
 
   /**
    * Calculates the feedforward from the gains and setpoints.
@@ -148,8 +160,8 @@ class SimpleMotorFeedforward {
     return MaxAchievableAcceleration(-maxVoltage, velocity);
   }
 
-  units::volt_t kS{0};
-  units::unit_t<kv_unit> kV{0};
-  units::unit_t<ka_unit> kA{0};
+  const units::volt_t kS;
+  const units::unit_t<kv_unit> kV;
+  const units::unit_t<ka_unit> kA;
 };
 }  // namespace frc