From bef7325884223580a1a8a893ed8002876cdac3ef Mon Sep 17 00:00:00 2001
From: Paul Riseborough <p_riseborough@live.com.au>
Date: Thu, 6 Apr 2017 13:00:07 +1000
Subject: [PATCH] EKF: protect covariance prediction from delta time errors

Allow time step to vary by a factor of 2 to allow for jitter.
---
 EKF/covariance.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/EKF/covariance.cpp b/EKF/covariance.cpp
index 0e2591ff54..461199c068 100644
--- a/EKF/covariance.cpp
+++ b/EKF/covariance.cpp
@@ -143,7 +143,7 @@ void Ekf::predictCovariance()
 	float dvy_b = _state.accel_bias(1);
 	float dvz_b = _state.accel_bias(2);
 
-	float dt = _imu_sample_delayed.delta_ang_dt;
+	float dt = math::constrain(_imu_sample_delayed.delta_ang_dt, 0.0005f * FILTER_UPDATE_PERIOD_MS, 0.002f * FILTER_UPDATE_PERIOD_MS);
 
 	// compute noise variance for stationary processes
 	float process_noise[_k_num_states] = {};