diff --git a/sw/in_progress/inertial/scilab/README b/sw/in_progress/inertial/scilab/README
index 523201b831..1c0b16f2cf 100644
--- a/sw/in_progress/inertial/scilab/README
+++ b/sw/in_progress/inertial/scilab/README
@@ -1,4 +1,4 @@
-tilt :
+0/ tilt
 
 
 1/ ahrs_euler
@@ -9,3 +9,6 @@ ahrs_euler_ekf_compm:
 ahrs_euler_ekf_seqm:
 	euler angles + bias estimation using ekf filter and sequential measurements ( one of each euler angle every update)
 
+
+2/ ahrs_quat
+
diff --git a/sw/in_progress/inertial/scilab/ahrs_quat_ekf_seqm.sce b/sw/in_progress/inertial/scilab/ahrs_quat_ekf_seqm.sce
index b4c68e31ed..6ef600efa0 100644
--- a/sw/in_progress/inertial/scilab/ahrs_quat_ekf_seqm.sce
+++ b/sw/in_progress/inertial/scilab/ahrs_quat_ekf_seqm.sce
@@ -1,7 +1,7 @@
 clear();
 getf('rotations.sci');
 getf('imu.sci');
-getf('ahrs_utils.sci');
+getf('ahrs_quat_utils.sci');
 getf('ekf.sci');
 
 use_sim = 1;
diff --git a/sw/in_progress/inertial/scilab/ahrs_quat_utils.sci b/sw/in_progress/inertial/scilab/ahrs_quat_utils.sci
new file mode 100644
index 0000000000..68ebb9f02d
--- /dev/null
+++ b/sw/in_progress/inertial/scilab/ahrs_quat_utils.sci
@@ -0,0 +1,104 @@
+
+
+
+
+
+//
+//
+//
+// Initialisation
+//
+//
+//
+function [X0] = ahrs_quat_init(avg_len, accel, mag, gyro) 
+
+ [AE0] = ahrs_euler_init(avg_len, accel, mag, gyro);
+
+ [quat] = quat_of_euler(AE0(1:3));
+
+ X0 = [ quat AE0(4:6) ]';
+
+endfunction
+
+
+
+
+
+
+
+
+
+
+//
+//
+//
+// Derivative of measure wrt state 
+//
+//
+//
+function [H] = ahrs_quat_get_dphi_dX(X)
+
+DCM = dcm_of_quat(X(1:4));
+phi_err = 2 / (DCM(3,3)^2 + DCM(2,3)^2);
+q0 = X(1);
+q1 = X(2);
+q2 = X(3);
+q3 = X(4);
+H = [
+    (q1 * DCM(3,3))                     * phi_err
+    (q0 * DCM(3,3) + 2 * q1 * DCM(2,3)) * phi_err
+    (q3 * DCM(3,3) + 2 * q2 * DCM(2,3)) * phi_err
+    (q2 * DCM(3,3))                     * phi_err
+    0
+    0
+    0
+    ]';
+
+endfunction
+
+
+
+
+
+
+
+
+function  [H] = ahrs_quat_get_dtheta_dX(X)
+
+DCM = dcm_of_quat(X(1:4));
+theta_err = 2 / sqrt(1 - DCM(1,3)^2);
+q0 = X(1);
+q1 = X(2);
+q2 = X(3);
+q3 = X(4);
+H = [
+     q2 * theta_err
+    -q3 * theta_err
+     q0 * theta_err
+    -q1 * theta_err
+     0
+     0
+     0
+    ]';
+
+endfunction
+
+function  [H] = ahrs_quat_get_dpsi_dX(X)
+
+DCM = dcm_of_quat(X(1:4));
+psi_err = 2 / (DCM(1,1)^2 + DCM(1,2)^2);
+q0 = X(1);
+q1 = X(2);
+q2 = X(3);
+q3 = X(4);
+H = [
+    (q3 * DCM(1,1))                     * psi_err
+    (q2 * DCM(1,1))                     * psi_err
+    (q1 * DCM(1,1) + 2 * q2 * DCM(1,2)) * psi_err
+    (q0 * DCM(1,1) + 2 * q3 * DCM(1,2)) * psi_err
+    0
+    0
+    0
+    ]';
+
+endfunction
\ No newline at end of file