diff --git a/conf/modules/dw1000_arduino.xml b/conf/modules/dw1000_arduino.xml
index 7d036ee34b..4e5893bfc6 100644
--- a/conf/modules/dw1000_arduino.xml
+++ b/conf/modules/dw1000_arduino.xml
@@ -8,6 +8,8 @@
       Decawave DW1000 modules (http://www.decawave.com/products/dwm1000-module) are Ultra-Wide-Band devices that can be used for communication and ranging.
       Especially, using 3 modules as anchors can provide data for a localization system based on trilateration.
       The DW1000 is using a SPI connection, but an arduino-compatible board can be used with the library https://github.com/thotro/arduino-dw1000 to hyde the low level drivers and provide direct ranging informations.
+
+      See https://hal-enac.archives-ouvertes.fr/hal-01936955 for more information on the EKF filtering.
     </description>
     <configure name="DW1000_ARDUINO_UART" value="UARTX" description="UART on which arduino and its DW1000 module is connected"/>
     <configure name="DW1000_ARDUINO_BAUD" value="B115200" description="UART Baudrate, default to 115200"/>
diff --git a/conf/modules/shift_tracking.xml b/conf/modules/shift_tracking.xml
index 45b2effffd..dd362fce5e 100644
--- a/conf/modules/shift_tracking.xml
+++ b/conf/modules/shift_tracking.xml
@@ -10,6 +10,8 @@
       with precision or in a net.
 
       Data are coming from POSITION_ESTIMATE ABI message.
+
+      See https://hal-enac.archives-ouvertes.fr/hal-01936955 for more information on UAV landing in a net.
     </description>
     <section name="SHIFT_TRACKING" prefix="SHIFT_TRACKING_">
       <define name="ID" value="ABI_BROADCAST" description="ABI binding ID"/>
diff --git a/sw/airborne/filters/pid.h b/sw/airborne/filters/pid.h
index 0e97529ac8..3d72f28633 100644
--- a/sw/airborne/filters/pid.h
+++ b/sw/airborne/filters/pid.h
@@ -117,6 +117,27 @@ static inline void set_gains_pid_f(struct PID_f *pid, float Kp, float Kd, float
   pid->g[2] = Ki;
 }
 
+/** Set integral part, can be used to reset.
+ *  The new sum of errors is calculated from current gains and bounds.
+ *
+ * @param pid pointer to PID structure
+ * @param value integral part of the PID control, 0. will reset it
+ */
+static inline void set_integral_pid_f(struct PID_f *pid, float value)
+{
+  float integral = value;
+  if (integral < -pid->max_sum) {
+    integral = -pid->max_sum;
+  } else if (integral > pid->max_sum) {
+    integral = pid->max_sum;
+  }
+  if (fabsf(pid->g[2]) < 1e-6) {
+    pid->sum = 0.f; // integral gain is too low, prevent division by zero, just reset sum
+  } else {
+    pid->sum = integral / pid->g[2];
+  }
+}
+
 
 
 /** Distcrete time PID structure.