Octanis Rover / Balloon: Mission Operations Manual

This documentation is being written and may change rapidly. Be sure to check back regularly! For information specific to the Octanis 1 mission see: mission_overview

Preface: This document (ORB MOM) contains information about each Rover / Balloon system and every phase of a generic Rover / Balloon mission. The Rover is a Balloon payload, but can be operated separately without regard to the Balloon mission.

• Rover: four-wheeled, solar-powered robot, capable of autonomous navigation, remote control and telemetry transmission.
• Balloon: assembly consisting of a weather balloon capable of carrying payloads of up to 2kg and a parachute for safe descent.
• Launch: the act of releasing the Balloon to flight.
• Deployment: the act of powering on the rover, uploading command data and letting it navigate to a destination.
• ★: a star indicates features to be implemented before the first mission.

The design has been substantially influenced by NASA's MUSES-CN nanorover whose goal was to send small, lightweight rovers to asteroids to explore. Due to the low gravitational field of asteroids, a conventional rover would easily flip over onto its back and be immobile.

The nanorover's design permits a high freedom of motion and so we apply the same to our rover. If the rover tips over, it can rotate itself to an upright position using its dynamic wheel struts. It can also use the struts to lift a wheel over a small obstacle to keep the body level. The body dimensions are 31cm x 31cm x 15cm.

Materials for wheels, struts and gearbox were chosen to withstand temperatures going down to -20°C and to resist solar UV radiation. The material of choice for external parts is ABS and PET. Insulating materials were chosen according to NASAs MLI guidelines, specifically our use of metalised polymer film as the outermost layer as radiation barriers. The rovers body is made of a shell of Styrofoam filled with an impact resistant Polyurethane core.

Custom mechanical parts are created on the lab 3d printer “Prusa i3 Hephestos”. This printer allows the use of ABS and PLA. The time required to print the largest part (wheel) currently is at 12 hours. Other parts like the metal gears are COTS or made from materials that have to be manually manipulated (Styrofoam/PU body, shafts, baseplate are cut manually.

The rover has four wheels, each containing a 12V DC motor with a reduction gearbox. Each wheel can turn with up to 7.9 RPM. A current sensor is used to measure the exact power consumption of each wheel and is used to notice motor stalls, which can imply that an obstacle was hit but not otherwise detected.

The wheels are replaceable and different wheels can be attached just by removing 4 screws. The diameter of a custom wheel should not exceed 20cm to stay within the motors limits. The maximum theoretical inclination achievable is measured to be 20° on snow with a total rover weight of 5 kg.

Each wheel is attached to a strut (4). Each strut can move in a circle around the common center axis of the rovers body (for this mission they are fixed). The center axis is a double shaft. One inside shaft inside the other shaft. The motion of the strut is achieved by driving the center shafts using a custom gearbox. The large herringbone gears (1) are 3D printed and attached to the shafts. They are driven by a gear set on a steel shaft (2) consisting of the herringbone pinion and a COTS worm drive. The worm drive locks the strut. The strut only moves when the motor (3) is powered. The motors powering the struts are attached to optical encoders allowing to locate the struts position.

The rover has a thick layer of insulation surrounding its internal electronics and payload. The insulation consists of layers of BoPET film, styrofoam and PU foam for rigidity. The outer BoPET film layer prevents convection and thus loss of heat. The insulation consists of top (1) and bottom (2) insulation boxes. These boxes are integral to the design as they are also carrying the solar panels and outdoor bay. The lid of the box can be easily opened to access the internals of the rover for maintenance and payload retrieval. Velcro strips are used to reattach the lid after maintenance.

The electronics modules, internal payload and strut gearboxes are all attached to a common base frame made from extruded aluminium profiles. Slots have been cut out of the insulation such that the base frame can fit inside. Thus the insulation boxes attach firmly onto the base frame.

The mass of the rover is 5kg including all payload systems. The struts and wheels motion strongly depend on the rovers mass. If a higher mass is required, higher power motors must be implemented and higher power demands must be satisfied by the rovers electrical systems.

The mainboard is the central computing unit that interfaces all peripherals of the rover, such as communication modules, sensors and actuators. The microcontroller of the mainboard is a TI MSP432, assuring low power consumption.

<fc #ff0000>Estimated</fc> autonomy while only driving continuously: 8h for a fully charged battery. Motors are assumeed to be operated in full speed (except when turning). Note that this estimation doesn't account for the consumption of other subsystems.

The mainboard can perform basic go-to-goal behaviour. It knows its current position thanks to (d)GPS, as well as its magnetic orientation, thanks to the BNO055 inertial measurement unit (IMU) or calculated GPS heading. It can store up to 20 target GPS locations which are being reached one by one. The rover will orient itself in an angle that points towards the current target location - errors on this angle are corrected with a PID motor control - and drives straight ahead until the goal is within a threshold of 0.5 meters (if dGPS is used).

<fc #c0c0c0>The BNO055 IMU needs to be calibrated after each power-up cycle, which means to perform a rotational movement in an “8”-shape while tilting and pivoting the rover body. A bad calibration status can lead to faulty direction information of the integrated compass (not needed for this mission).</fc>

<fc #c0c0c0>For a standard precision localization, a u-blox NEO-6M module can be used. A position accuracy of 2.5 m CEP (circular error probable - 50% of the measurements are within this radius away from the true location) can be expected at a 5 Hz update rate. Cold starts need 26 s to get a GPS fix. (not used in this mission)</fc>

Differential GPS (dGPS) is realized with the NEO-M8P module from u-blox. This requires a fixed basestation of which the exact coordinates are known, either by manually entering them or with “Survey-in” (an automatic position acquisition that takes in GPS data during ca. 0.5 - 1 hour). The base station then needs to communicate in permanence in order to perform the RTK (real time kinematic algorithm). The required communication channel is established with module like the HM-TRP Wireless Transceiver 868MhzHM-TRP Wireless Transceiver as already mounted on the u-blox M8P evaluation kit. ★

The dGPS system allows a position accuracy of 0.025 m + 1 ppm CEP when used in RTK mode (i.e. with basestation) at up to 5 Hz rate. It also calculates the heading information, which in this case is the direction of movement and can only be calculated while the rover is driving. Heading will be assumed unchanged while resting and is “North” at startup.

Regular data transmission is a mission critical feature of the rover. It is achieved by using the Iridium Short Burst Data (SBD) service with the help of the RockBLOCK Iridium 9602 modem. This modem allows the transmission of data packets of up to 340 bytes outwards (100 bytes message size is implemented) and 270 bytes inwards (currently not supported) approximately every 20 seconds. The key to this modem and network is that is available everywhere on Earth at any time, something that cannot be said of the GSM network or even amateur radio. Information sent through the Iridium network is automatically sent to a server and uploaded to the ground base station. For short-range communication from the rover to the field base station, a RN2483 LoRa tranceiver module with a theoretical range of 15km is used. For short-range debugging communications there is a Bluetooth Low Energy (BLE) module or a wired connection to UART0.

An external sensor module is connected to the mainboard via I2C. It will be used to collect accurate weather data. The weather module includes a temperature, pressure and humidity sensor, a UV irradiance sensor and a AS3935 lightning detection circuit which is able to estimate the distance to storms up to 40km away.

Mission items (or waypoints) are always stored on a non-volatile flash memory. In case of a reset of the mainboard, these can be retrieved and the rover can continue on its mission. However, the Operator has to re-arm the rover to continue (can be done over wireless LoRa link).

<fc #c0c0c0> Up to 8 HC-SR04 ultrasonic sensors can be mounted externally to the rover in order to perform obstacle avoidance. Obstacles as far as 4 m away from the rover can be taken into account, if needed. Detailed description here. These sensors are optional and are not used in Antarctic terrain. </fc>

A ARM Cortex A7 dual CPU, dual GPU single board computer (Olimex A20) is used for processes with higher computational power requirements like image processing. This board is easier to program (e.g. with Python) but requires orders of magnitude more power. It will be off when not needed.

The default power supply of the A20-OLinuXino-MICRO board was modified to be supplied from 5V. Connect the header called “5V_PWR” to the 5V_1 EPS output.

The mainboard uses the efficient MAVLink protocol to communicate with the base stations and with the SBC ROS instance. Any remote control software that supports MAVLink can be used for mission planning and display (e.g. QGroundControl).

MAVLink is also used over LoRa, Iridium and GSM. Application UART (UART0) can be switched between MAVLink and a shell.

The SBC ROS instance takes in mainboard sensor data (via mainboard application uart) and stereoscopy data (via USB cameras) and plans an appropriate path. The path is communicated to the mainboard using MAVLink (MAVROS).

Two cameras mounted on top of the rover are connected to the SBC in order to perform stereo vision for mapping and obstacle avoidance. More information can be found here.

An XV-11 LIDAR is mounted on the rover, pointing with a 45° angle to ground ahead of it. It scans the profile of the ground while the rover is moving forward. The data is processed in ROS and fused with IMU orientation data as well as dGPS information.

The angular resolution of the XV-11 LIDAR is one distance point per 1° rotation, at a refresh rate of 5 Hz. If a linear resolution on the ground of at least 5 cm is required, the maximum usable scanning width of the LIDAR is 247 cm, measured perpendicularly to the driving direction - corresponding to 120° or one third of all distance datapoints measured by the LIDAR. Detailed calculations are available here.

Using ROS (Robot Operating System) running on the SBC, 3D mapping of the ground will be performed and stored internally. The pose of the robot measured by the IMU will be taken into account by ROS and compensated for automatically.

Sending waypoints and receiving data can be done by using an Ethernet connection. Setup of the network card on the SBC and on the operators computer is required as follows. This must be done only once.:

• Rover configuration (Rover is delivered pre-configured)
  • auto eth0
  • iface eth0 inet static
  • address 192.168.2.19
  • netmask 255.255.255.0
  • gateway 192.168.2.1

• Operator Computer configuration (Depending on operator computer, the operator must set these settings themselves)
  • Static IP Address
  • IPv4 address: 192.168.2.1
  • Subnet mask: 255.255.255.0
  • Gateway: 192.168.2.1

The goal of the EPS is to provide two to three stabilized 3.3 V supplies, a 5 V supply and a 11V supply, as well as to control the inside temperature of the rover. Solar cells are used as power source. They are connected to the BQ24650 solar battery charger. Various (buck-)boost DC-DC regulators convert the battery voltage to the 3 system voltages if needed. Those can be requested to be switched on by sending the appropriate commands via I2C.

The MSP430FR5969 microcontroller on the EPS also has the ability to switch off different parts of the rover in case of emergency or to save energy. This includes the power for the mainboard to prevent deep unloading of the batteries (cut-off voltage of the battery is at 2.7 V) during a long phase of low incoming solar power. The EPS is designed to provide 3 separate regulated 3.3V voltage outputs at 2A output current each. The EPS provides 3 standard HexfetFETs that can turn on heaters if a higher temperature is required by certain modules.

The battery used is a MP176065XC Li-ion pack for extreme cold applications from SAFT with a nominal voltage of 3.65 V and nominal capacity of 6.5 Ah. It provides proper discharge for temperature as low as -50°C and charge temperature as low as -30°C. A backup temperature control of the battery is provided by the EPS heaters.

The solar panels have a rated output voltage of 3.6V per module and use cells with efficiency above 20%. Always two of them have to be connected in series in order to provide the solar battery charger with the required voltage. The maximum power point tracking of the BQ24650 is therefore adjusted to 7.2 V.

A periodic (~every second) interrupt signal is sent from the EPS to the mainboard controller, after which the latter needs to confirm the poll by sending a confirmation message via I2C. Failing to do so will result in a power cycle for the main 3.3V bus, which includes the mainboard and all its connected sensors. It is therefore crucial that the I2C connection and the interrupt pins between EPS and mainboard are properly connected.

This watchdog behaviour essentially detects and resolves problems like

• Crash of TI-RTOS
• unresponsiveness of the mainboard to incoming interrupts
• blocked I2C bus due to a failing slave device

Ground and field base stations can receive telemetry and send commands.

The field base station (FBS) is a physical device in proximity of the rover for wireless LoRa reception (868 MHz) or direct ethernet connection with the rover - both through the Communication Gateway. It can display received telemetry on the Operator's Laptop with installed APM planner. While in the field, the operator must connect the field base station to their personal computer (how to configure) via Ethernet cable and can then send MAVLink commands to the rover (done within APM Planner).

The base station of the differential GPS (dGPS) is also included in the FBS, as well as a power supply and control system, shutting down the base computer if necesary.

Schematic of the field base station.

The field base station comes with two parallel SAFT batteries (2x type: 1s2p INT 176065 xc; nominal Voltage: 3.65 V, capacity: 2 x 12.8 = 25.6 Ah). Requiring about 1 A (3.6 W), this is enough to operate the field base station for 20 h (as only 80% of the capacity is used) without external power source.

A 10 Wp solar pannel is provided to be connected to the solar input of the FBS to extend this operation time. Alternatively, a DC supply of 18 V can be connected to the solar input to recharge the batteries from an AC power supply.

Five LEDs indicate the system state of the FBS and a power button is there to manually shut down and boot the Communication Gateway and the dGPS base.

• <fc #00ff00>Battery full:</fc> If on, batteries are fully charged and external AC supply can be removed if FBS not operational. Blinks while batteries are charging.
• <fc #ffff00>Battery good:</fc> Indicates sufficient charge level of battery. If off, the Communication Gateway and dGPS base station cannot be turned on.
• <fc #ff0000>Supply on:</fc> Always on if minimally charged battery connected. If off even with battery, try plugging in the solar pannel or external AC supply to recharge. If still off, go to troubleshooting guide.
• <fc #ff0000>LoRa on:</fc> On if Communication Gateway is fully booted. Off if Communication Gateway is off. Blinking while booting/shutdown.
• <fc #ff0000>dGPS on:</fc> On if dGPS base station is running.
• Button: Press 3 sec (until you hear 1 beep) to TURN ON or OFF the Communication Gateway in order to connect a Laptop with APM planner running to receive and send messages to rover.

Press >6 sec (until you hear 2 beeps) to TURN OFF all systems.

After the batteries are plugged in, all systems will boot by default (GPS LED on, Comm GW LED starts blinking). It is not possible to turn off the systems during booting. Only after the LoRa LED is steadily on, the button can again be pressed for 3 sec to shut down the Communication Gateway in order to perform a survey in of the dGPS base. Turing off the Communication Gateway during dGPS survey-in and when not used by the operator is highly recommended to save power.

In order to charge the batteries ONLY, press the button long enough to turn off all systems, or hold the button while plugging in the batteries.

In order to determine the exact location of the FBS, the dGPS base needs to “survey-in”, which usually takes 30 minutes to one hour.

<fc #c0c0c0>The ground base station (GBS) is a piece of software running on a virtual server accessible from the internet. It receives messages that are forwarded from the Iridium network or direct connections from the GSM modem.</fc>

<fc #c0c0c0> Not yet relevant.

High Altitude Balloons or more commonly known, weather balloons, can be used to bring the rover over its target destination. Helium-filled, they typically float up to an altitude of 30km and a trajectory of hundreds of kilometers can be achieved solely by floating with the winds. This is the cheapest method to deploy the rover to Antarctica as it is only required to travel to lower South America, to which commercial flights exist, to launch the rover attached to the balloon. With this benefit comes a higher risk of deployment failure.

Once the balloon-rover-configuration have reached their target destination, the rover is separated from the balloon and parachutes to the ground. The balloon continues on uncontrolled and will eventually burst or float to the ground after the helium diffuses out.</fc>

<fc #c0c0c0> Not yet relevant.

Parachutes are essential for deploying the rover safely from high altitudes. We have devised a method to easily manufacture a correctly functioning parachute according to the model described in White et al . We use the fabric from 3 low cost umbrellas. These already have the desired shape, so we only add cords and cut a calculated hole in the center. The amount of parachutes, cords and size of the hole is topic of research.

</fc>

The rover ships with the following spares:

• 4 replacement wheels with flat profile.

Tools supplied:

• Screwdrivers for the eventual need to open the base station or to replace the wheels
• Kapton tape to perform small reparations
• Multimeter to measure certain electrical voltages
• JTAG programming interface (“Launchpad”) to flash new firmware to rover

The rover is packed together with the Field Base Station in a (L x B X H): 80 x 60 x 41 cm Zarges Eurobox (aluminum). The rover's camera head has to be removed from its body in order to fit it into the box. Also, the GPS communication antenna needs to be unscrewed.

The empty box gets filled step-by-step in the following way:

The empty box

Place the Field Base Solar Panel

Insert two spare wheels to the side wall(optional)

Place the box with the spare parts on top of the solar panel

Cover this box with the intermediate foam layer

Place two additional spare wheels to the side (optional)

Gently place the rover on top of the intermediate foam layer, with the laser pointing to the right. Remove the camera head of the rover and let it hang towards the front. Stabilize it with packing material and avoid it from touching the solar panels

Insert the base station holder to the left of the rover

Put the base station into its place. Remove both its antennas and stick them to the top lid of the base station using the velcro tape.

Fill in the space above the wheels with the Ethernet cables and the space next to the base station with AC power supply adapters (if needed).

Place the Tools/Foam layer on top of the base station.

Place the Operator's laptop onto this foam layer.

Cover everything with an additional layer of foam/styrofoam. Be very careful with the solar panels

Close the lid of the box.

This packing list does not contain the tripod of the field base station nor its battery pack, which must both be carried to the mission location separately

(Estimated) power autonomy assuming no incoming solar energy and ambient temperature > -40 °C

(Estimated) power autonomy assuming no incoming solar energy and ambient temperature > -40 °C

The normal operation procedures of the rover involve setting up the rover and base station hardware for a field mission and ensuring correct communications. Several checklists are referenced which are at the bottom of this page. The general schema of normal operations is the following:

CONSTELLATION ROVER DRIVING CHECKLIST

⁃place field station on tripod
⁃connect antennas and tilt antennas by 45° on field station.
⁃connect battery to field station
⁃connect solar panel to field station
⁃connect ethernet couplings to ethernet cables on field station
⁃turn on / verify power-up of field station via LEDs
⁃connect operator PC with ethernet cable to field station
⁃open APM planner (octanis version) and verify MAV024 is visible under “unmanned systems”
⁃WAIT for survey-in to occur
⁃verify survey-in occured by looking at MAVLink inspector -> MAV024 -> GPS_RAW_INT -> fix_type = 4 (survey in occured) 

⁃verify rover battery is inserted and connected
⁃connect both rover antennas and orient them vertically
⁃connect rover to field station via ethernet cable
⁃connect rovers own solar panel
⁃turn on rover via mechanical switch (followed by 3 short beeps)
⁃wait for another short beep, meaning the internal computer has booted
⁃verify LIDAR is spinning (after ~1 min.)
⁃open APM planner (octanis version) and verify MAV025 is visible under “unmanned sytems”
⁃toggle switch to “Net”
⁃Click on “Web Monitor” in the navbar. A browser will open a website served from the rover. Verify the camera images and that the rover is represented in the scene.
⁃Go back to APM planner: In “unmanned systems”, right click on MAV025 and select “control this system”
⁃Draw waypoints on the map
⁃Send waypoints by click “Write…” button under the waypoints list. Verify that “operation completed” is displayed
⁃In the Flight plan view, click on the “Activate Engines”/“ARM” button (BE PREPARED: the rover will drive when you hit the button)
⁃GENTLY unplug the Ethernet cable from the rover
⁃the rover will now drive all the waypoints and stop at the last one


CONSTELLATION ROVER WRAP-UP CHECKLIST

⁃turn off rover via mechanical switch and wait at least 3min or until you hear a short beep
⁃if rover needs charging: plugin rover battery charger OR use plugin rover solar panels if sun is available
⁃unplug battery if rover is going to storage for more than 2 days
⁃disconnect all ethernet cables and store them
⁃turn off field station by longpressing the button until you hear 2 beeps. If 2 of 3 red LEDs are off, disconnect battery if not needed for charging.

These steps have to be performed after the rover arrived in Antarctica and is taken out of the box for the first time.

• Open box and carefully take out the rover. Put it on a dry, stable surface.
• Verify the main switch is on “off”.
• Open the top of the rover at the front side velcro lid.
• Gently insert battery at the designated place and plug in its connector. You should hear one short beep.
• Close the lid again and seal the velcro strip.
• Connect the Rover power supply and let the battery charge for >3 hours.

Plug in the rover and the field base station to their respective power supply (Field Base Station Batteries must be connected with both plugs to the base station in order to be charged). To shorten charging time, press the button on the Base Station for ca. 10 seconds (until 2 beeps) to turn off the internal systems (only one red LED should remain on). Also make sure the rover main switch is on the “off” position.

• On the Operator's Laptop, open APM planner. Make sure to have an active internet connection.
• Zoom in to the location where the test mission should take place. Alternatively, click the Lat/Lon button on the bottom left corner of the map and enter the center coordinates manually.
• Shift + Left Mouseclick + drag a rectangle on the map to select the relevant test area. A grey selection box will be drawn.
• Click on “Cache” on the bottom left side of the map. In the pop-up window, check “Auto Multilayer Cache” and enter 21 layers.
• Click okay and wait for the download to complete.

APM Planner in disconnected state with a waypoint list example.

(This step may be done at a later stage on spot as well, but it is recommended to prepare it in advance)

• In APM planner, double click on the map to draw waypoints. Plan a mission path with long straight segments and let the rover make curves with a minimum radius of 3 meters. Draw an intermediate waypoint every 90° of the curve.
• A maximum of 20 waypoints only can be stored on the rover per mission.
• Remember the limitations of the rover: average speed is 200 meters per hour, a fully charged battery lasts for ca. 3 hours of driving (if no solar energy available), maximum slope 20°.
• Save the waypoints to a file as backup.

The following items are required to perform a test mission.

• Rover with connected battery inside and its two antennas
• Field Base Station with its two antennas.
• Field Base Station Battery Pack
• Field Base Station Solar Panel
• Field Base Station Tripod
• Operator's Laptop with built-in Ethernet connection or USB-to-Ethernet adapter.
• 2 Ethernet Cables

• Place the field base station in the vicinity of the test field. Mount it on its tripod that has to be stable and secured with some weight.
• Connect the two antennas before connecting the batteries into their respective positions. Orient the antennas in a 45° vertical angle in perpendicular directions from each other as in the picture.

Orientation of the base station antennas

• Connect the dedicated batteries (both connectors must be plugged in, the main battery plug and the “headphone” plug). You will hear 2 beeps, which indicates that all systems are turning on. Another short beep will indicate that the system has booted
• Connect the solar panel to the base station and orient it towards the sun. The green LED should start to blink.
• Press the button for 4 seconds (until 1st beep) to turn off the Communication Gateway. Like this, only the GPS base station is running and will perform a survey-in.
• Let the survey-in run for about one hour.

• After one hour, press the button again for 4 seconds (until 1st beep) to turn on the Communication Gateway. Connect the Operator's Laptop via Ethernet to the base station.
• Open APM planner. If not done yet, open Tool Widgets –> Mavlink Inspector. It should receive messages from “MAV 24”.

• In the mavlink inspector, expand the GPS_RAW_INT message and verify the field “Fix Type”. It should display at least the number 4 to indicate that survey-in is complete. If this is not the case, turn off the Communication Gateway again (click button for 4sec until 1st beep) and come back later again to repeat these steps.

• Take out the rover of its box and put it on a stable surface. Mount the camera head into its slot. Mount both antennas to their correct place and orient them vertically.
• Make sure the on-board solar panels are plugged in.
• Turn on the rover at its main switch. You should hear 3 beeps. Wait until you hear another beep to indicate that it has finished booted. The laser scanner should start to turn soon after.
• With a second ethernet cable, connect the rover to the Field Base Station, while keeping the Operator's laptop connected and the Communication Gateway on (3 red LEDs on the Field Base Station must be on). APM planner should now receive messages from “MAV 25” (=the rover). This may only start to happen after a few minutes.
• Wait to receive correct GPS messages (i.e. check the rover position on the map).
• Click on the “Web Monitor” button to check that the following systems are up and running:
  • Cameras (live images should be displayed)
  • Attitude information (3D graph of rover should show its orientation)
• If all systems are running normally, continue with the next steps.

• In APM planner, click the Flight Plan Tab.
• Load the prepared waypoints from the file to APM planner (or follow the steps to draw new waypoints).
• In the “Unmanned Systems” widget, right-click on System 25 (Rover) and click “Control this System”
• In the Mission Plan Widget, click “Write” to send the waypoints to the rover. Monitor the process and wait for completion (“done” is displayed in the bottom right corner). If “Operation timed out” is displayed, repeat the Write process.

• In APM planner, click on the Flight Data Tab to change the view.
• Make sure that the menu Tool Widgets → Control is activated.
• Click on “Activate Engine” or “ARM” in the Control widget

Note that the rover will then start to drive to the first waypoint immediately. You may now unplug the Ethernet cable from the rover and continue the control wirelessly.

1. Collect the rover from last waypoint. Turn off the rover with its main switch. Wait to hear a beep before continuing
2. Check FBS battery and Rover battery. If under 20%, leave in sunlight to recharge or use supplied AC wall adapter once returned to the base. Charging takes typically about 5 hours for the rover and max. 10 hours for the base station.
3. Stow rover and base station in the transport box as described above.

Balloon only

Work in progress.

Type of failure	Description of failure	Common Cause	Currently implemented workaround	Actions needed by operator	Status
SOFTWARE	I2C bus hangs up and blocks all tasks depending on it	because of BNO055 (IMU) readout. has been deactivated.	EPS detects that I2C communication is down and power cycles the mainboard including all I2C slaves	Predeployment procedure needs to be repeated	Critical:
HARDWARE	LIDAR no longer delivers any data	LIDAR is not spinning fast enough. This could be due to a frozen O-ring or dead motor.
SOFTWARE	Rover stops driving and gets disarmed automatically before reaching end of waypoint list	Reset may have occured.	Waypoints are backed up on flash memory. Operator needs to arm rover again to continue the route.
SOFTWARE	In the above described situation, rover does not continue going home after reaching the last waypoint in list, but drives back to the last waypoint of the list instead again	This is expected behaviour and can not be avoided atm	none.
SOFT/HARDWARE	Rover stops operating normally, occasionaly beeps repeatedly during 2 seconds.	Mainboard hangs up and EPS resets are unsuccessful. Should have been mitigated by complete shutdown of all systems, but does not seem to work properly		Turn off the rover with the main switch. Wait till hearing a long beep again. Then turn on the rover again with main switch. If this procedure does not help, turn it off again with the switch, wait till beep, and unplug the battery and any external power source such as solar cells and AC power supply. Wait for 2 minutes. Plug in batteries again and turn on system normally

Archived document for Risk management here