diff --git a/libraries/AP_Quaternion/AP_Quaternion.cpp b/libraries/AP_Quaternion/AP_Quaternion.cpp
index 1b4346657f..6c9455714e 100644
--- a/libraries/AP_Quaternion/AP_Quaternion.cpp
+++ b/libraries/AP_Quaternion/AP_Quaternion.cpp
@@ -269,27 +269,30 @@ void AP_Quaternion::update(void)
 	gyro = _imu->get_gyro();
 	accel = _imu->get_accel();
 
-	// keep a smoothed gyro vector for centripetal and reporting
-	// to mainline code
-	_gyro_smoothed = (_gyro_smoothed * 0.95) + (gyro * 0.05);
-
-	// Quaternion code uses opposite x and y gyro sense
+	// Quaternion code uses opposite x and y gyro sense from the
+	// rest of APM
 	gyro.x = -gyro.x;
 	gyro.y = -gyro.y;
 
+	// Quaternion code uses opposite z accel as well
+	accel.z = -accel.z;
 
 	if (_centripetal && _gps && _gps->status() == GPS::GPS_OK) {
+		// compensate for linear acceleration, limited to 1g
+		float acceleration = _gps->acceleration();
+		acceleration = constrain(acceleration, 0, 9.8);
+		accel.x -= acceleration;
+
 		// compensate for centripetal acceleration
 		float veloc;
 		veloc = _gps->ground_speed / 100;
-		accel.x -= _gps->acceleration();
-		accel.y -= _gyro_smoothed.z * veloc;
-		accel.z += _gyro_smoothed.y * veloc;
+		// be careful of the signs in this calculation. the
+		// quaternion system uses different signs than the
+		// rest of APM
+		accel.y -= (gyro.z - gyro_bias.z) * veloc;
+		accel.z += (gyro.y - gyro_bias.y) * veloc;
 	}
 
-	// Quaternion code uses opposite z accel
-	accel.z = -accel.z;
-
 	if (_compass == NULL) {
 		update_IMU(deltat, gyro, accel);
 	} else {
@@ -298,6 +301,9 @@ void AP_Quaternion::update(void)
 		update_MARG(deltat, gyro, accel, mag);
 	}
 
+	// keep the corrected gyro for reporting
+	_gyro_corrected = gyro;
+
 	// compute the Eulers
 	float test = (SEq_1*SEq_3 - SEq_4*SEq_2);
 	const float singularity = 0.499; // 86.3 degrees?
diff --git a/libraries/AP_Quaternion/AP_Quaternion.h b/libraries/AP_Quaternion/AP_Quaternion.h
index 4550a62dd2..543c37f579 100644
--- a/libraries/AP_Quaternion/AP_Quaternion.h
+++ b/libraries/AP_Quaternion/AP_Quaternion.h
@@ -59,8 +59,14 @@ public:
 	// compatibility methods with DCM
 	void update_DCM(void) { update(); }
 	void update_DCM_fast(void) { update(); }
-	Vector3f get_gyro(void) { return _gyro_smoothed; }
-	Vector3f get_integrator(void) { return gyro_bias; }
+	Vector3f get_gyro(void) {
+		// notice the sign reversals here
+		return Vector3f(-_gyro_corrected.x, -_gyro_corrected.y, _gyro_corrected.z);
+	}
+	Vector3f get_integrator(void) {
+		// notice the sign reversals here
+		return Vector3f(-gyro_bias.x, -gyro_bias.y, gyro_bias.z);
+        }
 	float get_accel_weight(void) { return 0; }
 	float get_renorm_val(void) { return 0; }
 	float get_health(void) { return 0; }
@@ -91,10 +97,11 @@ private:
 	// true if we are doing centripetal acceleration correction
 	bool		_centripetal;
 
-	// maximum gyroscope measurement error in rad/s (set to 5 degrees/second)
-	static const float gyroMeasError = 5.0 * (M_PI/180.0);
+	// maximum gyroscope measurement error in rad/s (set to 10 degrees/second)
+	static const float gyroMeasError = 10.0 * (M_PI/180.0);
 
-	// maximum gyroscope drift rate in radians/s/s (set to 0.02 degrees/s/s)
+	// maximum gyroscope drift rate in radians/s/s (set to 0.02
+	// degrees/s/s, which is 1.2 degrees/s/minute)
 	static const float gyroMeasDrift = 0.02 * (PI/180.0);
 
 	float beta;
@@ -109,8 +116,8 @@ private:
 	// estimate gyroscope biases error
 	Vector3f gyro_bias;
 
-	// smoothed gyro estimate
-	Vector3f _gyro_smoothed;
+	// the current corrected gyro vector
+	Vector3f _gyro_corrected;
 
 	// estimate of error
 	float		_error_rp_sum;