diff --git a/gtsam/navigation/AHRSFactor.h b/gtsam/navigation/AHRSFactor.h
index 78dea0181..17531c8a4 100644
--- a/gtsam/navigation/AHRSFactor.h
+++ b/gtsam/navigation/AHRSFactor.h
@@ -28,16 +28,11 @@ public:
     double deltaTij;
     Matrix3 delRdelBiasOmega;
     Matrix PreintMeasCov;
-    bool use2ndOrderIntegration_;
 
     PreintegratedMeasurements(const imuBias::ConstantBias& bias,
-        const Matrix3& measurementAccCovariance,
-        const Matrix3& measuredOmegaCovariance,
-        const Matrix3& integrationErrorCovariance,
-        const bool use2ndOrderIntegration = false) :
+        const Matrix3& measuredOmegaCovariance) :
           biasHat(bias), measurementCovariance(3,3), delRdelBiasOmega(
-              Matrix3::Zero()), PreintMeasCov(3,3), use2ndOrderIntegration_(
-                  use2ndOrderIntegration) {
+              Matrix3::Zero()), PreintMeasCov(3,3) {
 //      measurementCovariance << integrationErrorCovariance, Matrix3::Zero(), Matrix3::Zero(), Matrix3::Zero(), measurementAccCovariance, Matrix3::Zero(), Matrix3::Zero(), Matrix3::Zero(), measuredOmegaCovariance;
       measurementCovariance <<measuredOmegaCovariance;
       PreintMeasCov = Matrix::Zero(3,3);
@@ -77,19 +72,15 @@ public:
       PreintMeasCov = Matrix::Zero(9, 9);
     }
 
-    void integrateMeasurement(const Vector3& measuredAcc,
+    void integrateMeasurement(
         const Vector3& measuredOmega, double deltaT,
         boost::optional<const Pose3&> body_P_sensor = boost::none) {
-      Vector3 correctedAcc = biasHat.correctAccelerometer(measuredAcc);
       Vector3 correctedOmega = biasHat.correctGyroscope(measuredOmega);
 
       if (body_P_sensor) {
         Matrix3 body_R_sensor = body_P_sensor->rotation().matrix();
         correctedOmega = body_R_sensor * correctedOmega;
         Matrix3 body_omega_body_cross = skewSymmetric(correctedOmega);
-        correctedAcc = body_R_sensor * correctedAcc
-            - body_omega_body_cross * body_omega_body_cross
-            * body_P_sensor->translation().vector();
       }
       const Vector3 theta_incr = correctedOmega * deltaT;
       const Rot3 Rincr = Rot3::Expmap(theta_incr);
@@ -156,7 +147,6 @@ private:
   Vector3 gravity_;
   Vector3 omegaCoriolis_;
   boost::optional<Pose3> body_P_sensor_;
-  bool use2ndOrderCoriolis_;
 
 public:
 
@@ -169,21 +159,17 @@ public:
 
   /** Default constructor - only use for serialization */
   AHRSFactor() :
-    preintegratedMeasurements_(imuBias::ConstantBias(), Matrix3::Zero(),
-        Matrix3::Zero(), Matrix3::Zero()) {
-  }
+    preintegratedMeasurements_(imuBias::ConstantBias(), Matrix3::Zero()) {}
 
   AHRSFactor(Key rot_i, Key rot_j, Key bias,
       const PreintegratedMeasurements& preintegratedMeasurements,
-      const Vector3& gravity, const Vector3& omegaCoriolis,
-      boost::optional<const Pose3&> body_P_sensor = boost::none,
-      const bool use2ndOrderCoriolis = false) :
+      const Vector3& omegaCoriolis,
+      boost::optional<const Pose3&> body_P_sensor = boost::none) :
         Base(
             noiseModel::Gaussian::Covariance(
                 preintegratedMeasurements.PreintMeasCov), rot_i, rot_j, bias), preintegratedMeasurements_(
-                    preintegratedMeasurements), gravity_(gravity), omegaCoriolis_(
-                        omegaCoriolis), body_P_sensor_(body_P_sensor), use2ndOrderCoriolis_(
-                            use2ndOrderCoriolis) {
+                    preintegratedMeasurements), omegaCoriolis_(
+                        omegaCoriolis), body_P_sensor_(body_P_sensor) {
   }
 
   virtual ~AHRSFactor() {}
@@ -203,7 +189,6 @@ public:
         << keyFormatter(this->key2()) << "," << keyFormatter(this->key3())
         << ",";
     preintegratedMeasurements_.print("  preintegrated measurements:");
-    std::cout << "  gravity: [ " << gravity_.transpose() << " ]" << std::endl;
     std::cout << "  omegaCoriolis: [ " << omegaCoriolis_.transpose() << " ]"
         << std::endl;
     this->noiseModel_->print("  noise model: ");
@@ -216,7 +201,6 @@ public:
     const This *e = dynamic_cast<const This*>(&expected);
     return e != NULL && Base::equals(*e, tol)
     && preintegratedMeasurements_.equals(e->preintegratedMeasurements_, tol)
-    && equal_with_abs_tol(gravity_, e->gravity_, tol)
     && equal_with_abs_tol(omegaCoriolis_, e->omegaCoriolis_, tol)
     && ((!body_P_sensor_ && !e->body_P_sensor_)
         || (body_P_sensor_ && e->body_P_sensor_
@@ -227,9 +211,6 @@ public:
     return preintegratedMeasurements_;
   }
 
-  const Vector3& gravity() const {
-    return gravity_;
-  }
 
   const Vector3& omegaCoriolis() const {
     return omegaCoriolis_;
@@ -321,9 +302,9 @@ public:
   static void Predict(const Rot3& rot_i, const Rot3& rot_j,
       const imuBias::ConstantBias& bias,
       const PreintegratedMeasurements preintegratedMeasurements,
-      const Vector3& gravity, const Vector3& omegaCoriolis,
-      boost::optional<const Pose3&> body_P_sensor = boost::none,
-      const bool use2ndOrderCoriolis = false) {
+      const Vector3& omegaCoriolis,
+      boost::optional<const Pose3&> body_P_sensor = boost::none
+      ) {
 
     const double& deltaTij = preintegratedMeasurements.deltaTij;
 //    const Vector3 biasAccIncr = bias.accelerometer()
@@ -360,7 +341,6 @@ private:
     & boost::serialization::make_nvp("NoiseModelFactor3",
         boost::serialization::base_object<Base>(*this));
     ar & BOOST_SERIALIZATION_NVP(preintegratedMeasurements_);
-    ar & BOOST_SERIALIZATION_NVP(gravity_);
     ar & BOOST_SERIALIZATION_NVP(omegaCoriolis_);
     ar & BOOST_SERIALIZATION_NVP(body_P_sensor_);
   }
diff --git a/gtsam/navigation/tests/testAHRSFactor.cpp b/gtsam/navigation/tests/testAHRSFactor.cpp
index 21a310864..7f6fa69a8 100644
--- a/gtsam/navigation/tests/testAHRSFactor.cpp
+++ b/gtsam/navigation/tests/testAHRSFactor.cpp
@@ -48,27 +48,27 @@ Rot3 evaluateRotationError(const AHRSFactor& factor, const Rot3 rot_i,
 }
 
 AHRSFactor::PreintegratedMeasurements evaluatePreintegratedMeasurements(
-    const imuBias::ConstantBias& bias, const list<Vector3>& measuredAccs,
-    const list<Vector3>& measuredOmegas, const list<double>& deltaTs,
+    const imuBias::ConstantBias& bias,
+    const list<Vector3>& measuredOmegas,
+    const list<double>& deltaTs,
     const Vector3& initialRotationRate = Vector3(0.0, 0.0, 0.0)) {
-  AHRSFactor::PreintegratedMeasurements result(bias, Matrix3::Identity(),
-      Matrix3::Identity(), Matrix3::Identity());
+  AHRSFactor::PreintegratedMeasurements result(bias, Matrix3::Identity());
 
-  list<Vector3>::const_iterator itAcc = measuredAccs.begin();
   list<Vector3>::const_iterator itOmega = measuredOmegas.begin();
   list<double>::const_iterator itDeltaT = deltaTs.begin();
-  for (; itAcc != measuredAccs.end(); ++itAcc, ++itOmega, ++itDeltaT) {
-    result.integrateMeasurement(*itAcc, *itOmega, *itDeltaT);
+  for (; itOmega != measuredOmegas.end(); ++itOmega, ++itDeltaT) {
+    result.integrateMeasurement(*itOmega, *itDeltaT);
   }
 
   return result;
 }
 
 Rot3 evaluatePreintegratedMeasurementsRotation(
-    const imuBias::ConstantBias& bias, const list<Vector3>& measuredAccs,
-    const list<Vector3>& measuredOmegas, const list<double>& deltaTs,
+    const imuBias::ConstantBias& bias,
+    const list<Vector3>& measuredOmegas,
+    const list<double>& deltaTs,
     const Vector3& initialRotationRate = Vector3(0.0, 0.0, 0.0)) {
-  return evaluatePreintegratedMeasurements(bias, measuredAccs, measuredOmegas,
+  return evaluatePreintegratedMeasurements(bias, measuredOmegas,
       deltaTs, initialRotationRate).deltaRij;
 }
 
@@ -88,7 +88,6 @@ TEST( AHRSFactor, PreintegratedMeasurements ) {
   imuBias::ConstantBias bias(Vector3(0, 0, 0), Vector3(0, 0, 0)); ///< Current estimate of acceleration and angular rate biases
 
   // Measurements
-  Vector3 measuredAcc(0.1, 0.0, 0.0);
   Vector3 measuredOmega(M_PI / 100.0, 0.0, 0.0);
   double deltaT = 0.5;
 
@@ -96,11 +95,9 @@ TEST( AHRSFactor, PreintegratedMeasurements ) {
   Rot3 expectedDeltaR1 = Rot3::RzRyRx(0.5 * M_PI / 100.0, 0.0, 0.0);
   double expectedDeltaT1(0.5);
 
-  bool use2ndOrderIntegration = true;
   // Actual preintegrated values
-  AHRSFactor::PreintegratedMeasurements actual1(bias, Matrix3::Zero(),
-      Matrix3::Zero(), Matrix3::Zero(), use2ndOrderIntegration);
-  actual1.integrateMeasurement(measuredAcc, measuredOmega, deltaT);
+  AHRSFactor::PreintegratedMeasurements actual1(bias, Matrix3::Zero());
+  actual1.integrateMeasurement(measuredOmega, deltaT);
 
   EXPECT(assert_equal(expectedDeltaR1, actual1.deltaRij, 1e-6));
   DOUBLES_EQUAL(expectedDeltaT1, actual1.deltaTij, 1e-6);
@@ -111,7 +108,7 @@ TEST( AHRSFactor, PreintegratedMeasurements ) {
 
   // Actual preintegrated values
   AHRSFactor::PreintegratedMeasurements actual2 = actual1;
-  actual2.integrateMeasurement(measuredAcc, measuredOmega, deltaT);
+  actual2.integrateMeasurement(measuredOmega, deltaT);
 
   EXPECT(assert_equal(expectedDeltaR2, actual2.deltaRij, 1e-6));
   DOUBLES_EQUAL(expectedDeltaT2, actual2.deltaTij, 1e-6);
@@ -131,15 +128,12 @@ TEST( ImuFactor, Error ) {
   omegaCoriolis << 0, 0, 0;
   Vector3 measuredOmega;
   measuredOmega << M_PI / 100, 0, 0;
-  Vector3 measuredAcc = x1.unrotate(-Point3(gravity)).vector();
   double deltaT = 1.0;
-  bool use2ndOrderIntegration = true;
-  AHRSFactor::PreintegratedMeasurements pre_int_data(bias, Matrix3::Zero(),
-      Matrix3::Zero(), Matrix3::Zero(), use2ndOrderIntegration);
-  pre_int_data.integrateMeasurement(measuredAcc, measuredOmega, deltaT);
+  AHRSFactor::PreintegratedMeasurements pre_int_data(bias, Matrix3::Zero());
+  pre_int_data.integrateMeasurement(measuredOmega, deltaT);
 
   // Create factor
-  AHRSFactor factor(X(1), X(2), B(1), pre_int_data, gravity, omegaCoriolis,
+  AHRSFactor factor(X(1), X(2), B(1), pre_int_data, omegaCoriolis,
       false);
 
   Vector errorActual = factor.evaluateError(x1, x2, bias);
@@ -192,26 +186,21 @@ TEST( ImuFactor, ErrorWithBiases ) {
   Rot3 x2(Rot3::Expmap(Vector3(0, 0, M_PI / 4.0 + M_PI / 10.0)));
 
   // Measurements
-  Vector3 gravity;
-  gravity << 0, 0, 9.81;
   Vector3 omegaCoriolis;
   omegaCoriolis << 0, 0.1, 0.1;
   Vector3 measuredOmega;
   measuredOmega << 0, 0, M_PI / 10.0 + 0.3;
-  Vector3 measuredAcc = x1.unrotate(-Point3(gravity)).vector()
-      + Vector3(0.2, 0.0, 0.0);
   double deltaT = 1.0;
 
   AHRSFactor::PreintegratedMeasurements pre_int_data(
-      imuBias::ConstantBias(Vector3(0.2, 0.0, 0.0), Vector3(0.0, 0.0, 0.0)),
-      Matrix3::Zero(), Matrix3::Zero(), Matrix3::Zero());
-  pre_int_data.integrateMeasurement(measuredAcc, measuredOmega, deltaT);
+      imuBias::ConstantBias(Vector3(0.2, 0.0, 0.0), Vector3(0.0, 0.0, 0.0)), Matrix3::Zero());
+  pre_int_data.integrateMeasurement(measuredOmega, deltaT);
 
 //  ImuFactor::PreintegratedMeasurements pre_int_data(bias.head(3), bias.tail(3));
 //    pre_int_data.integrateMeasurement(measuredAcc, measuredOmega, deltaT);
 
   // Create factor
-  AHRSFactor factor(X(1), X(2), B(1), pre_int_data, gravity, omegaCoriolis);
+  AHRSFactor factor(X(1), X(2), B(1), pre_int_data, omegaCoriolis);
 
   SETDEBUG("ImuFactor evaluateError", false);
   Vector errorActual = factor.evaluateError(x1, x2, bias);
@@ -344,16 +333,13 @@ TEST( AHRSFactor, FirstOrderPreIntegratedMeasurements ) {
   Pose3 body_P_sensor(Rot3::Expmap(Vector3(0, 0.1, 0.1)), Point3(1, 0, 1));
 
   // Measurements
-  list<Vector3> measuredAccs, measuredOmegas;
+  list<Vector3> measuredOmegas;
   list<double> deltaTs;
-  measuredAccs.push_back(Vector3(0.1, 0.0, 0.0));
   measuredOmegas.push_back(Vector3(M_PI / 100.0, 0.0, 0.0));
   deltaTs.push_back(0.01);
-  measuredAccs.push_back(Vector3(0.1, 0.0, 0.0));
   measuredOmegas.push_back(Vector3(M_PI / 100.0, 0.0, 0.0));
   deltaTs.push_back(0.01);
   for (int i = 1; i < 100; i++) {
-    measuredAccs.push_back(Vector3(0.05, 0.09, 0.01));
     measuredOmegas.push_back(
         Vector3(M_PI / 100.0, M_PI / 300.0, 2 * M_PI / 100.0));
     deltaTs.push_back(0.01);
@@ -361,14 +347,14 @@ TEST( AHRSFactor, FirstOrderPreIntegratedMeasurements ) {
 
   // Actual preintegrated values
   AHRSFactor::PreintegratedMeasurements preintegrated =
-      evaluatePreintegratedMeasurements(bias, measuredAccs, measuredOmegas,
+      evaluatePreintegratedMeasurements(bias, measuredOmegas,
           deltaTs, Vector3(M_PI / 100.0, 0.0, 0.0));
 
   // Compute numerical derivatives
   Matrix expectedDelRdelBias =
       numericalDerivative11<Rot3, imuBias::ConstantBias>(
           boost::bind(&evaluatePreintegratedMeasurementsRotation, _1,
-              measuredAccs, measuredOmegas, deltaTs,
+              measuredOmegas, deltaTs,
               Vector3(M_PI / 100.0, 0.0, 0.0)), bias);
   Matrix expectedDelRdelBiasAcc = expectedDelRdelBias.leftCols(3);
   Matrix expectedDelRdelBiasOmega = expectedDelRdelBias.rightCols(3);
@@ -397,8 +383,6 @@ TEST( AHRSFactor, ErrorWithBiasesAndSensorBodyDisplacement ) {
   omegaCoriolis << 0, 0.1, 0.1;
   Vector3 measuredOmega;
   measuredOmega << 0, 0, M_PI / 10.0 + 0.3;
-  Vector3 measuredAcc = x1.unrotate(-Point3(gravity)).vector()
-      + Vector3(0.2, 0.0, 0.0);
   double deltaT = 1.0;
 
   const Pose3 body_P_sensor(Rot3::Expmap(Vector3(0, 0.10, 0.10)),
@@ -409,12 +393,12 @@ TEST( AHRSFactor, ErrorWithBiasesAndSensorBodyDisplacement ) {
 
   AHRSFactor::PreintegratedMeasurements pre_int_data(
       imuBias::ConstantBias(Vector3(0.2, 0.0, 0.0), Vector3(0.0, 0.0, 0.0)),
-      Matrix3::Zero(), Matrix3::Zero(), Matrix3::Zero());
+      Matrix3::Zero());
 
-  pre_int_data.integrateMeasurement(measuredAcc, measuredOmega, deltaT);
+  pre_int_data.integrateMeasurement(measuredOmega, deltaT);
 
   // Create factor
-  AHRSFactor factor(X(1), X(2), B(1), pre_int_data, gravity, omegaCoriolis);
+  AHRSFactor factor(X(1), X(2), B(1), pre_int_data, omegaCoriolis);
 
   // Expected Jacobians
   Matrix H1e = numericalDerivative11<Rot3>(
@@ -458,7 +442,7 @@ TEST (AHRSFactor, graphTest) {
   Vector3 omegaCoriolis;
   omegaCoriolis << 0, 0, 0;
   AHRSFactor::PreintegratedMeasurements pre_int_data(biasHat,
-      Matrix3::Identity(), Matrix3::Identity(), Matrix3::Identity());
+      Matrix3::Identity());
 
   // Pre-integrate measurements
   Vector3 measuredAcc(0.0, 0.0, 0.0);
@@ -473,10 +457,10 @@ TEST (AHRSFactor, graphTest) {
   NonlinearFactorGraph graph;
   Values values;
   for(size_t i = 0; i < 5; ++i) {
-    pre_int_data.integrateMeasurement(measuredAcc, measuredOmega, deltaT);
+    pre_int_data.integrateMeasurement(measuredOmega, deltaT);
   }
 //  pre_int_data.print("Pre integrated measurementes");
-  AHRSFactor factor(X(1), X(2), B(1), pre_int_data, gravity, omegaCoriolis);
+  AHRSFactor factor(X(1), X(2), B(1), pre_int_data, omegaCoriolis);
   values.insert(X(1), x1);
   values.insert(X(2), x2);
   values.insert(B(1), bias);