Fix docker sim build

Using EXTENDED_SYS_STATE message

.github/workflows/build.yml

@@ -46,7 +46,7 @@ jobs:
       run: python3 tools/check_c_cpp_properties.py
 
   build_simulator:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
     - name: Install Arduino CLI
       uses: arduino/setup-arduino-cli@v1.1.1
@@ -63,6 +63,26 @@ jobs:
         path: gazebo/build/*.so
         retention-days: 1
 
+  build_simulator_docker:
+    runs-on: ubuntu-latest
+    container:
+      image: ubuntu:20.04
+    steps:
+    - name: Install Arduino CLI
+      uses: arduino/setup-arduino-cli@v1.1.1
+    - uses: actions/checkout@v4
+    - name: Install Gazebo
+      run: curl -sSL http://get.gazebosim.org | sh
+    - name: Install SDL2
+      run: apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install build-essential libsdl2-dev -y
+    - name: Build simulator
+      run: make build_simulator
+    - uses: actions/upload-artifact@v4
+      with:
+        name: gazebo-plugin-binary
+        path: gazebo/build/*.so
+        retention-days: 1
+
   build_simulator_macos:
     runs-on: macos-latest
     if: github.event_name == 'workflow_dispatch'

.vscode/extensions.json

@@ -2,7 +2,6 @@
 	// See https://go.microsoft.com/fwlink/?LinkId=827846 to learn about workspace recommendations.
 	"recommendations": [
 		"ms-vscode.cpptools",
-		"twxs.cmake",
 		"ms-vscode.cmake-tools",
 		"ms-python.python"
 	],

Makefile

@@ -16,7 +16,7 @@ dependencies .dependencies:
 	arduino-cli core install esp32:esp32@3.1.0 --config-file arduino-cli.yaml
 	arduino-cli lib update-index
 	arduino-cli lib install "FlixPeriph"
-	arduino-cli lib install "MAVLink"@2.0.12
+	arduino-cli lib install "MAVLink"@2.0.16
 	touch .dependencies
 
 gazebo/build cmake: gazebo/CMakeLists.txt

README.md

@@ -32,17 +32,17 @@
 
 ## It actually flies
 
-See detailed demo video (for version 0): https://youtu.be/8GzzIQ3C6DQ.
+See detailed demo video: https://youtu.be/hT46CZ1CgC4.
+
+<a href="https://youtu.be/hT46CZ1CgC4"><img width=500 src="https://i3.ytimg.com/vi/hT46CZ1CgC4/maxresdefault.jpg"></a>
+
+Version 0 demo video: https://youtu.be/8GzzIQ3C6DQ.
 
 <a href="https://youtu.be/8GzzIQ3C6DQ"><img width=500 src="https://i3.ytimg.com/vi/8GzzIQ3C6DQ/maxresdefault.jpg"></a>
 
-Version 1 test flight: https://t.me/opensourcequadcopter/42.
-
-<a href="https://t.me/opensourcequadcopter/42"><img width=500 src="docs/img/flight-video.jpg"></a>
-
 See the [user builds gallery](docs/user.md).
 
-<img src="docs/img/user/user.jpg" width=400>
+<a href="docs/user.md"><img src="docs/img/user/user.jpg" width=400></a>
 
 ## Simulation
 
@@ -57,7 +57,7 @@ See [instructions on running the simulation](docs/build.md).
 |Type|Part|Image|Quantity|
 |-|-|:-:|:-:|
 |Microcontroller board|ESP32 Mini|<img src="docs/img/esp32.jpg" width=100>|1|
-|IMU (and barometer²) board|GY‑91 (or other MPU‑9250/MPU‑6500 board), ICM‑20948³|<img src="docs/img/gy-91.jpg" width=90 align=center><img src="docs/img/icm-20948.jpg" width=100>|1|
+|IMU (and barometer²) board|GY‑91, MPU-9265 (or other MPU‑9250/MPU‑6500 board), ICM‑20948³|<img src="docs/img/gy-91.jpg" width=90 align=center><img src="docs/img/icm-20948.jpg" width=100>|1|
 |Motor|8520 3.7V brushed motor (shaft 0.8mm).<br>Motor with exact 3.7V voltage is needed, not ranged working voltage (3.7V — 6V).|<img src="docs/img/motor.jpeg" width=100>|4|
 |Propeller|Hubsan 55 mm|<img src="docs/img/prop.jpg" width=100>|4|
 |MOSFET (transistor)|100N03A or [analog](https://t.me/opensourcequadcopter/33)|<img src="docs/img/100n03a.jpg" width=100>|4|
@@ -70,7 +70,7 @@ See [instructions on running the simulation](docs/build.md).
 |Frame bottom part|3D printed⁴:<br>[`flix-frame-1.1.stl`](docs/assets/flix-frame-1.1.stl) [`flix-frame-1.1.step`](docs/assets/flix-frame-1.1.step)|<img src="docs/img/frame1.jpg" width=100>|1|
 |Frame top part|3D printed:<br>[`esp32-holder.stl`](docs/assets/esp32-holder.stl) [`esp32-holder.step`](docs/assets/esp32-holder.step)|<img src="docs/img/esp32-holder.jpg" width=100>|1|
 |Washer for IMU board mounting|3D printed:<br>[`washer-m3.stl`](docs/assets/washer-m3.stl) [`washer-m3.step`](docs/assets/washer-m3.step)|<img src="docs/img/washer-m3.jpg" width=100>|2|
-|*RC transmitter (optional)*|*KINGKONG TINY X8 or other⁵*|<img src="docs/img/tx.jpg" width=100>|1|
+|*RC transmitter (optional)*|*KINGKONG TINY X8 (warning: lacks USB support) or other⁵*|<img src="docs/img/tx.jpg" width=100>|1|
 |*RC receiver (optional)*|*DF500 or other⁵*|<img src="docs/img/rx.jpg" width=100>|1|
 |Wires|28 AWG recommended|<img src="docs/img/wire-28awg.jpg" width=100>||
 |Tape, double-sided tape||||

docs/build.md

@@ -109,7 +109,7 @@ The latest version of Ubuntu supported by Gazebo 11 simulator is 20.04. If you h
 3. Install ESP32 core, version 3.1.0 (version 2.x is not supported). See the [official Espressif's instructions](https://docs.espressif.com/projects/arduino-esp32/en/latest/installing.html#installing-using-arduino-ide) on installing ESP32 Core in Arduino IDE.
 4. Install the following libraries using [Library Manager](https://docs.arduino.cc/software/ide-v2/tutorials/ide-v2-installing-a-library):
    * `FlixPeriph`, the latest version.
-   * `MAVLink`, version 2.0.12.
+   * `MAVLink`, version 2.0.16.
 5. Clone the project using git or [download the source code as a ZIP archive](https://codeload.github.com/okalachev/flix/zip/refs/heads/master).
 6. Open the downloaded Arduino sketch `flix/flix.ino` in Arduino IDE.
 7. Connect your ESP32 board to the computer and choose correct board type in Arduino IDE (*WEMOS D1 MINI ESP32* for ESP32 Mini) and the port.
@@ -160,7 +160,7 @@ Before flight you need to calibrate the accelerometer:
 
 1. Install [QGroundControl mobile app](https://docs.qgroundcontrol.com/master/en/qgc-user-guide/getting_started/download_and_install.html#android) on your smartphone.
 2. Power the drone using the battery.
-3. Connect your smartphone to the appeared `flix` Wi-Fi network.
+3. Connect your smartphone to the appeared `flix` Wi-Fi network (password: `flixwifi`).
 4. Open QGroundControl app. It should connect and begin showing the drone's telemetry automatically.
 5. Go to the settings and enable *Virtual Joystick*. *Auto-Center Throttle* setting **should be disabled**.
 6. Use the virtual joystick to fly the drone!
@@ -180,7 +180,7 @@ If your drone doesn't have RC receiver installed, you can use USB remote control
 1. Install [QGroundControl](https://docs.qgroundcontrol.com/master/en/qgc-user-guide/getting_started/download_and_install.html) app on your computer.
 2. Connect your USB remote control to the computer.
 3. Power up the drone.
-4. Connect your computer to the appeared `flix` Wi-Fi network.
+4. Connect your computer to the appeared `flix` Wi-Fi network (password: `flixwifi`).
 5. Launch QGroundControl app. It should connect and begin showing the drone's telemetry automatically.
 6. Go the the QGroundControl menu ⇒ *Vehicle Setup* ⇒ *Joystick*. Calibrate you USB remote control there.
 7. Use the USB remote control to fly the drone!

docs/troubleshooting.md

@@ -16,7 +16,6 @@ Do the following:
 * **Make sure correct IMU model is chosen**. If using ICM-20948 board, change `MPU9250` to `ICM20948` everywhere in the `imu.ino` file.
 * **Check if the CLI is working**. Perform `help` command in Serial Monitor. You should see the list of available commands. You can also access the CLI using QGroundControl (*Vehicle Setup* ⇒ *Analyze Tools* ⇒ *MAVLink Console*).
 * **Configure QGroundControl correctly before connecting to the drone** if you use it to control the drone. Go to the settings and enable *Virtual Joystick*. *Auto-Center Throttle* setting **should be disabled**.
-* **Make sure you're not moving the drone several seconds after the power on**. The drone calibrates its gyroscope on the start so it should stay still for a while.
 * **Check the IMU is working**. Perform `imu` command and check its output:
   * The `status` field should be `OK`.
   * The `rate` field should be about 1000 (Hz).

docs/user.md

@@ -4,6 +4,17 @@ This page contains user-built drones based on the Flix project. Publish your pro
 
 ---
 
+Author: [@cryptokobans](https://t.me/cryptokobans).<br>
+Features: ESP32-C3 SuperMini board, INA226 power monitor, IRLZ44N MOSFETs, MPU-6500 IMU.
+
+**Flight video:**
+
+<a href="https://drive.google.com/file/d/1-4ciDsj8slTEaxxRl1-QAkx0cUDkb8iy/view?usp=sharing"><img height=300 src="img/user/cryptokobans/video.jpg"></a>
+
+<img src="img/user/cryptokobans/1.jpg" height=150> <img src="img/user/cryptokobans/2.jpg" height=150>
+
+---
+
 Author: [@jeka_chex](https://t.me/jeka_chex).<br>
 Features: custom frame, FPV camera, 3-blade 31 mm propellers.<br>
 Motor drivers: AON7410 MOSFET + capacitors.<br>
@@ -17,27 +28,14 @@ Custom frame files: https://drive.google.com/drive/folders/1QCIc-_YYFxJN4cMhVLjL
 
 <a href="https://drive.google.com/file/d/1RSU6VWs9omsge4hGloH5NQqnxvLyhMKB/view?usp=sharing"><img height=300 src="img/user/jeka_chex/video-fpv.jpg"></a>
 
-<table>
-	<tr>
-		<td><img src="img/user/jeka_chex/1.jpg" height=150></td>
-		<td><img src="img/user/jeka_chex/2.jpg" height=150></td>
-		<td><img src="img/user/jeka_chex/3.jpg" height=150></td>
-		<td><img src="img/user/jeka_chex/4.jpg" height=150></td>
-		<td><img src="img/user/jeka_chex/5.jpg" height=150></td>
-	</tr>
-</table>
+<img src="img/user/jeka_chex/1.jpg" height=150> <img src="img/user/jeka_chex/2.jpg" height=150> <img src="img/user/jeka_chex/3.jpg" height=150> <img src="img/user/jeka_chex/4.jpg" height=150> <img src="img/user/jeka_chex/5.jpg" height=150>
 
 ---
 
 Author: [@fisheyeu](https://t.me/fisheyeu).<br>
 [Video](https://drive.google.com/file/d/1IT4eMmWPZpmaZR_qsIRmNJ52hYkFB_0q/view?usp=share_link).
 
-<table>
-	<tr>
-		<td><img src="img/user/fisheyeu/1.jpg" height=300></td>
-		<td><img src="img/user/fisheyeu/2.jpg" height=300></td>
-	</tr>
-</table>
+<img src="img/user/fisheyeu/1.jpg" height=300> <img src="img/user/fisheyeu/2.jpg" height=300>
 
 ---
 
@@ -46,13 +44,7 @@ Custom propellers guard 3D-model: https://drive.google.com/file/d/1TKnzwvrZYzYuR
 Features: ESP32-C3 microcontroller is used.<br>
 [Video](https://drive.google.com/file/d/1B0NMcsk0fgwUgNr9XuLOdR2yYCuaj008/view?usp=share_link).
 
-<table>
-	<tr>
-		<td><img src="img/user/p_kabakov/1.jpg" width=150></td>
-		<td><img src="img/user/p_kabakov/2.jpg" width=150></td>
-		<td><img src="img/user/p_kabakov/3.jpg" width=150></td>
-	</tr>
-</table>
+<img src="img/user/p_kabakov/1.jpg" width=150> <img src="img/user/p_kabakov/2.jpg" width=150> <img src="img/user/p_kabakov/3.jpg" width=150>
 
 **Custom Wi-Fi RC control:**
 
@@ -65,12 +57,7 @@ See source and description (in Russian): https://github.com/pavelkabakov/flix/tr
 Author: [@yi_lun](https://t.me/yi_lun).<br>
 [Video](https://drive.google.com/file/d/1TkSuvHQ_0qQPFUpY5XjJzmhnpX_07cTg/view?usp=share_link).
 
-<table>
-	<tr>
-		<td><img src="img/user/yi_lun/1.jpg" width=300></td>
-		<td><img src="img/user/yi_lun/2.jpg" width=300></td>
-	</tr>
-</table>
+<img src="img/user/yi_lun/1.jpg" width=300> <img src="img/user/yi_lun/2.jpg" width=300>
 
 ---
 
@@ -81,12 +68,7 @@ Schematics: https://miro.com/app/board/uXjVN-dTjoo=/?moveToWidget=34587646121795
 
 <a href="https://www.youtube.com/watch?v=wi4w_hOmKcQ"><img width=500 src="img/user/peter_ukhov-2/video.jpg"></a>
 
-<table>
-	<tr>
-		<td><img src="img/user/peter_ukhov-2/1.jpg" width=300></td>
-		<td><img src="img/user/peter_ukhov-2/2.jpg" width=300></td>
-	</tr>
-</table>
+<img src="img/user/peter_ukhov-2/1.jpg" width=300> <img src="img/user/peter_ukhov-2/2.jpg" width=300>
 
 ---
 
@@ -95,15 +77,7 @@ Files for 3D printing of the custom frame: https://drive.google.com/file/d/1tkNm
 
 <a href="https://t.me/opensourcequadcopter/61"><img width=500 src="img/user/alexey_karakash/video.jpg"></a>
 
-<table>
-	<tr>
-		<td><img src="img/user/alexey_karakash/1.jpg" height=150></td>
-		<td><img src="img/user/alexey_karakash/2.jpg" height=150></td>
-		<td><img src="img/user/alexey_karakash/3.jpg" height=150></td>
-		<td><img src="img/user/alexey_karakash/4.jpg" height=150></td>
-		<td><img src="img/user/alexey_karakash/5.jpg" height=150></td>
-	</tr>
-</table>
+<img src="img/user/alexey_karakash/1.jpg" height=150> <img src="img/user/alexey_karakash/2.jpg" height=150> <img src="img/user/alexey_karakash/3.jpg" height=150> <img src="img/user/alexey_karakash/4.jpg" height=150> <img src="img/user/alexey_karakash/5.jpg" height=150>
 
 ---
 
@@ -111,13 +85,7 @@ Author: [@rudpa](https://t.me/rudpa).<br>
 
 <a href="https://t.me/opensourcequadcopter/46"><img width=500 src="img/user/rudpa/video.jpg"></a>
 
-<table>
-	<tr>
-		<td><img src="img/user/rudpa/1.jpg" height=150></td>
-		<td><img src="img/user/rudpa/2.jpg" height=150></td>
-		<td><img src="img/user/rudpa/3.jpg" height=150></td>
-	</tr>
-</table>
+<img src="img/user/rudpa/1.jpg" height=150> <img src="img/user/rudpa/2.jpg" height=150> <img src="img/user/rudpa/3.jpg" height=150>
 
 ---
 
@@ -126,10 +94,4 @@ Schematics: https://miro.com/app/board/uXjVN-dTjoo=/?moveToWidget=34587646123382
 
 <a href="https://t.me/opensourcequadcopter/24"><img width=500 src="img/user/peter_ukhov/video.jpg"></a>
 
-<table>
-	<tr>
-		<td><img src="img/user/peter_ukhov/1.jpg" height=150></td>
-		<td><img src="img/user/peter_ukhov/2.jpg" height=150></td>
-		<td><img src="img/user/peter_ukhov/3.jpg" height=150></td>
-	</tr>
-</table>
+<img src="img/user/peter_ukhov/1.jpg" height=150> <img src="img/user/peter_ukhov/2.jpg" height=150> <img src="img/user/peter_ukhov/3.jpg" height=150>

flix/cli.ino

@@ -34,7 +34,6 @@ const char* motd =
 "mot - show motor output\n"
 "log - dump in-RAM log\n"
 "cr - calibrate RC\n"
-"cg - calibrate gyro\n"
 "ca - calibrate accel\n"
 "mfr, mfl, mrr, mrl - test motor (remove props)\n"
 "reset - reset drone's state\n"
@@ -109,6 +108,7 @@ void doCommand(String str, bool echo = false) {
 		print("acc: %f %f %f\n", acc.x, acc.y, acc.z);
 		printIMUCal();
 		print("rate: %f\n", loopRate);
+		print("landed: %d\n", landed);
 	} else if (command == "rc") {
 		print("Raw: throttle %d yaw %d pitch %d roll %d armed %d mode %d\n",
 			channels[throttleChannel], channels[yawChannel], channels[pitchChannel],
@@ -124,8 +124,6 @@ void doCommand(String str, bool echo = false) {
 		dumpLog();
 	} else if (command == "cr") {
 		calibrateRC();
-	} else if (command == "cg") {
-		calibrateGyro();
 	} else if (command == "ca") {
 		calibrateAccel();
 	} else if (command == "mfr") {

flix/estimate.ino

@@ -29,7 +29,7 @@ void applyGyro() {
 void applyAcc() {
 	// test should we apply accelerometer gravity correction
 	float accNorm = acc.norm();
-	bool landed = !motorsActive() && abs(accNorm - ONE_G) < ONE_G * 0.1f;
+	landed = !motorsActive() && abs(accNorm - ONE_G) < ONE_G * 0.1f;
 
 	if (!landed) return;
 

flix/flix.ino

@@ -18,6 +18,7 @@ Vector gyro; // gyroscope data
 Vector acc; // accelerometer data, m/s/s
 Vector rates; // filtered angular rates, rad/s
 Quaternion attitude; // estimated attitude
+bool landed; // are we landed and stationary
 float motors[4]; // normalized motors thrust in range [-1..1]
 
 void setup() {

flix/imu.ino

@@ -5,6 +5,7 @@
 
 #include <SPI.h>
 #include <MPU9250.h>
+#include "lpf.h"
 #include "util.h"
 
 MPU9250 IMU(SPI);
@@ -17,8 +18,6 @@ void setupIMU() {
 	print("Setup IMU\n");
 	IMU.begin();
 	configureIMU();
-	delay(500); // wait a bit before calibrating
-	calibrateGyro();
 }
 
 void configureIMU() {
@@ -32,6 +31,7 @@ void readIMU() {
 	IMU.waitForData();
 	IMU.getGyro(gyro.x, gyro.y, gyro.z);
 	IMU.getAccel(acc.x, acc.y, acc.z);
+	calibrateGyroOnce();
 	// apply scale and bias
 	acc = (acc - accBias) / accScale;
 	gyro = gyro - gyroBias;
@@ -47,21 +47,13 @@ void rotateIMU(Vector& data) {
 	// Axes orientation for various boards: https://github.com/okalachev/flixperiph#imu-axes-orientation
 }
 
-void calibrateGyro() {
-	const int samples = 1000;
-	print("Calibrating gyro, stand still\n");
-	IMU.setGyroRange(IMU.GYRO_RANGE_250DPS); // the most sensitive mode
+void calibrateGyroOnce() {
+	static float landedTime = 0;
+	landedTime = landed ? landedTime + dt : 0;
+	if (landedTime < 2) return; // calibrate only if definitely stationary
 
-	gyroBias = Vector(0, 0, 0);
-	for (int i = 0; i < samples; i++) {
-		IMU.waitForData();
-		IMU.getGyro(gyro.x, gyro.y, gyro.z);
-		gyroBias = gyroBias + gyro;
-	}
-	gyroBias = gyroBias / samples;
-
-	printIMUCal();
-	configureIMU();
+	static LowPassFilter<Vector> gyroCalibrationFilter(0.001);
+	gyroBias = gyroCalibrationFilter.update(gyro);
 }
 
 void calibrateAccel() {
@@ -88,6 +80,7 @@ void calibrateAccel() {
 	calibrateAccelOnce();
 
 	printIMUCal();
+	print("✓ Calibration done!\n");
 	configureIMU();
 }
 
@@ -113,9 +106,6 @@ void calibrateAccelOnce() {
 	if (acc.x < accMin.x) accMin.x = acc.x;
 	if (acc.y < accMin.y) accMin.y = acc.y;
 	if (acc.z < accMin.z) accMin.z = acc.z;
-	print("acc %f %f %f\n", acc.x, acc.y, acc.z);
-	print("max %f %f %f\n", accMax.x, accMax.y, accMax.z);
-	print("min %f %f %f\n", accMin.x, accMin.y, accMin.z);
 	// Compute scale and bias
 	accScale = (accMax - accMin) / 2 / ONE_G;
 	accBias = (accMax + accMin) / 2;

flix/mavlink.ino

@@ -33,19 +33,23 @@ void sendMavlink() {
 	if (t - lastSlow >= PERIOD_SLOW) {
 		lastSlow = t;
 
-		mavlink_msg_heartbeat_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg, MAV_TYPE_QUADROTOR,
-			MAV_AUTOPILOT_GENERIC, MAV_MODE_FLAG_MANUAL_INPUT_ENABLED | (armed ? MAV_MODE_FLAG_SAFETY_ARMED : 0),
+		mavlink_msg_heartbeat_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg, MAV_TYPE_QUADROTOR, MAV_AUTOPILOT_GENERIC,
+			MAV_MODE_FLAG_MANUAL_INPUT_ENABLED | (armed * MAV_MODE_FLAG_SAFETY_ARMED) | ((mode == STAB) * MAV_MODE_FLAG_STABILIZE_ENABLED),
 			0, MAV_STATE_STANDBY);
 		sendMessage(&msg);
+
+		mavlink_msg_extended_sys_state_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg,
+			MAV_VTOL_STATE_UNDEFINED, landed ? MAV_LANDED_STATE_ON_GROUND : MAV_LANDED_STATE_IN_AIR);
+		sendMessage(&msg);
 	}
 
 	if (t - lastFast >= PERIOD_FAST) {
 		lastFast = t;
 
 		const float zeroQuat[] = {0, 0, 0, 0};
-		Quaternion attitudeFRD = fluToFrd(attitude); // MAVLink uses FRD coordinate system
+		Quaternion att = fluToFrd(attitude); // MAVLink uses FRD coordinate system
 		mavlink_msg_attitude_quaternion_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg,
-			time, attitudeFRD.w, attitudeFRD.x, attitudeFRD.y, attitudeFRD.z, rates.x, rates.y, rates.z, zeroQuat);
+			time, att.w, att.x, att.y, att.z, rates.x, rates.y, rates.z, zeroQuat);
 		sendMessage(&msg);
 
 		mavlink_msg_rc_channels_scaled_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg, controlsTime * 1000, 0,

flix/parameters.ino

@@ -48,9 +48,6 @@ Parameter parameters[] = {
 	{"ACC_SCALE_X", &accScale.x},
 	{"ACC_SCALE_Y", &accScale.y},
 	{"ACC_SCALE_Z", &accScale.z},
-	{"GYRO_BIAS_X", &gyroBias.x},
-	{"GYRO_BIAS_Y", &gyroBias.y},
-	{"GYRO_BIAS_Z", &gyroBias.z},
 	// rc
 	{"RC_NEUTRAL_0", &channelNeutral[0]},
 	{"RC_NEUTRAL_1", &channelNeutral[1]},

gazebo/flix.h

@@ -21,6 +21,7 @@ Vector acc;
 Vector gyro;
 Vector rates;
 Quaternion attitude;
+bool landed;
 
 // declarations
 void step();

gazebo/models/flix/flix.sdf

@@ -1,6 +1,7 @@
 <?xml version="1.0"?>
 <sdf version="1.5">
 	<model name="flix">
+		<plugin name="flix" filename="libflix.so"/>
 		<link name="body">
 			<inertial>
 				<mass>0.065</mass>
@@ -23,38 +24,14 @@
 				<update_rate>1000</update_rate>
 				<imu>
 					<angular_velocity>
-						<x>
-							<noise type="gaussian">
-								<stddev>0.00174533</stddev><!-- 0.1 degrees per second -->
-							</noise>
-						</x>
-						<y>
-							<noise type="gaussian">
-								<stddev>0.00174533</stddev>
-							</noise>
-						</y>
-						<z>
-							<noise type="gaussian">
-								<stddev>0.00174533</stddev>
-							</noise>
-						</z>
+						<x><noise type="gaussian"><stddev>0.00174533</stddev></noise></x><!-- 0.1 degrees per second -->
+						<y><noise type="gaussian"><stddev>0.00174533</stddev></noise></y>
+						<z><noise type="gaussian"><stddev>0.00174533</stddev></noise></z>
 					</angular_velocity>
 					<linear_acceleration>
-						<x>
-							<noise type="gaussian">
-								<stddev>0.0784</stddev><!-- 8 mg -->
-							</noise>
-						</x>
-						<y>
-							<noise type="gaussian">
-								<stddev>0.0784</stddev>
-							</noise>
-						</y>
-						<z>
-							<noise type="gaussian">
-								<stddev>0.0784</stddev>
-							</noise>
-						</z>
+						<x><noise type="gaussian"><stddev>0.0784</stddev></noise></x><!-- 8 mg -->
+						<y><noise type="gaussian"><stddev>0.0784</stddev></noise></y>
+						<z><noise type="gaussian"><stddev>0.0784</stddev></noise></z>
 					</linear_acceleration>
 				</imu>
 			</sensor>
@@ -90,6 +67,5 @@
 				<material><ambient>1 1 1 0.5</ambient><diffuse>1 1 1 0.5</diffuse></material>
 			</visual>
 		</link>
-		<plugin name="flix" filename="libflix.so"/>
 	</model>
 </sdf>