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Betaflight GPS Rescue mode is much like “Return to Dwelling” on a DJI drone. This characteristic is designed to fly your FPV drone again to its launch level and land it mechanically in a failsafe or when your video feed will get sketchy. On this tutorial, I’m going to stroll you thru establishing GPS Rescue Mode, testing it, and I’ll additionally share some recommendations on enhancing its efficiency and troubleshooting widespread points.
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Why GPS Rescue is a Recreation-Changer
Betaflight’s default failsafe motion is dropping the quad to the bottom. Now, with the most recent GPS Rescue Mode, your drone can return near its launch level and land by itself! That is extremely helpful for long-range flights. Actually, I’ve misplaced rely of what number of occasions GPS Rescue has saved my drones.
How you can Select the Finest GPS?
Listed here are the concerns when choosing a great GPS for Rescue mode:
- M10 GPS is the perfect.
- It Ought to Help UBLOX protocol, keep away from NMEA protocol because it solely helps 1Hz replace fee and that’s too sluggish.
- Get the most important GPS you possibly can comfortably slot in your drone – larger GPS comes with larger antenna and it’s higher for sign.
- In case your GPS doesn’t reliably provide you with greater than 10 satellites out of doors, it’s dangerous to make use of.
GPS Suggestions
See my GPS testing right here: https://oscarliang.com/gps-review/
Prime Performer: GEPRC M1025Q
Prime Performer: HGLRC M100 5883
Smallest Price Having: GOKU GM10 Nano V3
Smallest Price Having: FlyFishRC M10 Mini
Smallest Price Having: HGLRC M100 Mini
Choosing a smaller GPS module helps save weight, nevertheless it does imply you’ll sacrifice a little bit of sensitivity that comes with fashions with a big antenna.
Technology of GPS Chip
Most GPS modules for FPV drones use both an M8, M9 or M10 chip. M10 chips are the most recent and provide the perfect efficiency, able to connecting concurrently to 4 International GNSS programs (GPS, Galileo, Glonass, and Beidou). This leads to sooner lock-ons and connections to extra satellites. Regardless of their superior efficiency, the worth of M10 GPS is much like M8, making them a cheap improve.
Antenna Scratches
Observed scratches in your GPS antenna’s metallic patch? Don’t fear; this isn’t essentially an indication of defect or injury. It’s usually the results of manufacturing facility tuning to make sure optimum frequency. A lot of these antenna have a nominal tuned frequency, however are sometimes impacted by development, parts location and soldering. Inserting small nicks within the centre of the lengthy edges, or corners, can advantageous tune its frequency.
Is a Barometer Wanted?
A barometer measures altitude utilizing air strain, and whereas many flight controllers include one built-in, e.g. the BMP280 (such because the Speedybee F405 V4 and RushFPV F722 V2). Barometer isn’t mandatory for Rescue mode, however it may well enhance altitude estimations accuracy, leads to higher altitude management and extra dependable landings. Simply bear in mind, if you happen to’re making use of conformal coating for water resistance, keep away from coating the barometer.
Some GPS modules provide a built-in barometer for an additional value. In case your flight controller doesn’t have one, including a module with a barometer could possibly be useful.
Is a Compass Crucial?
A compass (as generally known as magnetometer in Betaflight) is for figuring out which course the drone is heading.
Betaflight GPS Rescue Mode DOES NOT require a compass to work, however utilizing one can enhance Rescue mode efficiency, particularly in conditions with crosswinds or throughout place maintain, as a result of it offers correct heading data no matter motion course. With out a compass, Betaflight estimates heading from GPS knowledge, which could be inaccurate when the drone is drifting (like in a crosswind), inflicting inefficient corrections.
Nonetheless, whereas a compass can improve efficiency, it provides complexity. It requires cautious setup in Betaflight, further wiring, correct mounting orientation, and calibration. It’s additionally delicate to electrical noise, which might result in inaccurate readings. For most individuals, a compass isn’t mandatory until you may have particular necessities.
Some GPS modules have built-in compass: GPS with out compass have 4 wires, whereas these with a compass usually have 6 wires. The 2 further wires are to connect with the i2c port on the flight controller (SCL and SDA).
Connecting GPS to Flight Controller
Wiring a GPS module to the flight controller is kind of simple. Merely join it on to any accessible UART on the FC, (TX to RX, RX to TX), and energy it with 5V.
- GPS RX – FC TX
- GPS TX – FC RX
- GPS 5V – FC 5V
- GPS GND – FC GND
- GPS SDA – FC SDA (if GPS has a compass)
- GPS SCL – FC SCL (if GPS has a compass)
Keep away from utilizing Softserial on your GPS connection, because it’s restricted to a 19200 baud fee. At 9600 baud, GPS reliability for Rescue Mode is compromised. A {hardware} serial port is your best choice for a steady and dependable connection.
Some flight controllers, just like the Speedybee F405, characteristic 4V5 pads. These are primarily the identical as 5V pads however have the additional benefit of drawing energy from USB. That is significantly useful for these occasions when the GPS is taking some time looking for satellites. Through the use of the USB for energy, you keep away from the chance of your VTX overheating whereas ready on the bottom with a LiPo battery plugged in. It additionally helps the GPS lock sooner for the reason that VTX isn’t transmitting and inflicting interference. Word that some FCs would possibly provide 5V pads powered by USB however below completely different labels; examine with a multimeter if not sure.
How you can Setup GPS in Betaflight
GPS Rescue mode in Betaflight is repeatedly evolving, so it’s essential to make use of the most recent firmware model for brand new options and bug fixes. I like to recommend upgrading to Betaflight v4.5 for this course of: https://oscarliang.com/betaflight-4-5/
First, within the Configuration tab of the Betaflight Configurator, activate GPS for navigation and telemetry below the Different Options part. If GPS all the time deactivates after a reboot, it could be as a result of not choosing GPS within the Cloud Construct choices throughout firmware flashing.
Subsequent, within the Ports tab, assign GPS to the suitable UART below “Sensor Enter.” Betaflight helps varied baud charges: 9600, 19200, 38400, 57600, 115200. If you’re not sure what baudrate your GPS module helps, choosing AUTO normally works.
The beneficial baud fee for 10Hz GPS knowledge fee is 38400 or 57600. There may be little to be gained by utilizing 115200 with 10hz, however utilizing decrease baud charges cut back the CPU load and are extra proof against electrical noise.
| GPS Knowledge Fee | Baud Fee | CPU Load | Feedback |
| 20Hz | 115200 | Highest | M10 solely; check fastidiously! |
| 10Hz | 38400 or larger | Medium | 10Hz and 57600 is beneficial for GPS Rescue |
| 5Hz | 19200 or larger | Medium | Okay settings for common use |
| 1Hz-2Hz | 9600 or larger | Least | Too sluggish for clean GPS rescue, OK for easy place/velocity data |
Within the GPS tab, do the next:
- Choose UBLOX because the Protocol, which is the usual for many GPS.
- Allow Auto Config.
- Allow Use Galileo – it improves positioning accuracy.
- Allow Set Dwelling Level As soon as to stop resetting the house location with every arm/disarm cycle till you unplug the battery.
- Select Auto-detect for Floor Help Kind to boost positioning accuracy.
- Save and Reboot.
After establishing, the GPS indicator on the high of the configurator ought to gentle up, indicating communication with the FC. A purple icon means GPS is speaking to the FC however with no lock, and a yellow icon signifies a profitable GPS lock.
If the GPS indicator stays off, examine for
- GPS isn’t powered? Attempt plugging in battery?
- Incorrect parameters, for example, unsuitable baud fee or protocol.
- Incorrect wiring, strive swapping TX and RX.
How you can examine if GPS is working?
Questioning in case your GPS module is speaking to the flight controller? The ‘gpspassthrough’ command within the CLI can reveal any ongoing knowledge trade. Seeing a stream of binary knowledge means communication is going on.
Run the ‘gpspassthrough‘ command within the CLI can reveal any ongoing knowledge trade between the FC and GPS.
Seeing a stream of hieroglyphic binary knowledge characters means communication is going on. If you happen to see nothing, there could also be a difficulty with energy, UART connection, or your setup.
Ready for GPS Lock
Getting a GPS lock, or “3D repair,” requires locking onto at the very least 4 satellites and might take a couple of minutes.
Once you energy up the GPS module for the primary time in a brand new location, it all the time takes longer to seek for satellites, generally known as a “chilly begin”. Subsequent begins are usually faster because the module remembers satellite tv for pc positions (for instance while you change battery).
It’s tougher to get a lock indoor. If you need to check this inside the home, attempt to get near the home windows with the antenna pointing to the sky.
You will note GPS associated data below the GPS tab, the place it reveals the standing of your lock, your GPS coordinates and site on a map, verifying the accuracy of your GPS lock.
LED Indicators
On most GPS such because the BN220, BN180 and BN880, there are two LED indicators, labelled “TX” (normally blue) and “PPS” (normally purple).
Flashing blue (TX) signifies UART connection. Whether it is off, then the GPS isn’t sending knowledge out. That is additionally an indicator of the refresh fee, in 1Hz it ought to flash as soon as per second, whereas in 5Hz it would flash 5 occasions a second.
Flashing purple (PPS) signifies the 2D/3D repair standing of the GPS. If “PPS” is off then you definitely don’t have a repair but.
When it will get a 3D repair, the purple LED on the BN-220 module ought to blink (along with the blue LED).
OSD
You may show GPS data within the OSD. Try this tutorial about Betaflight OSD in case you are not accustomed to it. You may show GPS coordinates, distance and course to residence and extra.
To know what number of satellite tv for pc have been acquired, place the gps sats factor in your OSD. 6-8 is the minimal for rescue mode to work, the extra the higher. Your GPS coordinates will even get extra correct while you purchase extra satellites.
You can too show HDOP subsequent to the variety of satellites. HDOP is a measurement of the well being of the GPS locks. A HDOP worth of 1 or beneath is good, which might provide you with an accuracy of about 2.5 meters or much less. It could be oversimplying, however simply consider it as how a lot the drone can be drifting horizontally in meters.
To do that, go to the CLI, and enter:
set osd_gps_sats_show_hdop = on
save
Radio Telemetry
After getting GPS setup and acquired a lock, go to the radio’s telemetry web page, choose “Uncover new sensors”. Some GPS associated new sensors ought to seem together with GPS coordinates. This solely works in case your radio system helps Telemetry – corresponding to ExpressLRS and Crossfire.
This lets you log GPS coordinates in your radio, it permits you to maintain monitor of the final recognized place of your plane. This may be useful for looking for the misplaced quadcopter if you happen to can’t see the coordinates in your DVR.
Testing Angle Mode
Betaflight’s GPS Rescue mode depends on Angle mode (a self-leveling flight mode) to stabilize the drone. Subsequently, it’s important to make sure Angle mode is functioning accurately.
First, confirm that the Accelerometer is enabled within the Configuration tab.
Subsequent, proceed to the Setup tab and calibrate the Accelerometer on a degree floor. Failure to take action would possibly end result within the drone drifting whereas in Angle mode.
To check Angle mode, strive hovering the drone to see if it’s self-levelling as anticipated. Bear in mind, Angle mode makes use of solely the Accelerometer and Gyro, so it received’t maintain the drone completely stationary like a DJI drone would. A slight drift as a result of weight distribution and wind is regular, so long as the drone stays steady. If drifting is noticeable, you possibly can trim the accelerometer within the Configuration tab to reduce it utilizing stick instructions on the bottom (however unlikely to fully get rid of it so don’t fear).
Additionally, pay attention to the throttle place throughout hover (with a half discharged battery). This worth shall be helpful when establishing Rescue mode later.
Disabling Magnetometer
As beneficial by Betaflight Builders, until you’re completely certain that your Magnetometer (aka compass) has been correctly calibrated and is working accurately, in any other case you must disable it (within the Configuration tab, below Accelerometer and Barometer). Betaflight Rescue Mode doesn’t rely on Magnetometer so it’s advantageous to disable it.
To examine in case your magnetometer is working, examine the compass worth in your telephone (set to indicate True North, not Magnetic North), with the heading on Configurator’s predominant opening display, the GPS tab in Configurator, or the Sensors tab debug line 5 in debug mode GPS_RESCUE_HEADING, and examine that each are inside 10 levels of one another. If the heading all the time begins at North, and follows quick actions shortly however then jumps to another worth, the Magazine isn’t proper.
Keep away from Utilizing 8K/8K
As per builders suggestions, keep away from 8K PID Loop Frequency, use 4K or decrease. That is because of the CPU intensive nature of Rescue Mode, particularly with excessive baud fee corresponding to 56700 or larger. Decreasing PID looptime will go away extra CPU headroom for Rescue mode to work extra reliably.
Enabling GPS Rescue Mode in Failsafe
Navigate to the Failsafe tab within the Betaflight Configurator. If you happen to can’t discover this tab, ensure you’ve enabled the “Knowledgeable Mode” possibility on the high of the display (subsequent to the Replace Firmware button).
Beneath Stage 2, choose GPS Rescue. Now, in case your drone enters failsafe, it would set off GPS Rescue Mode.
So, what precisely is failsafe, and what are stage 1 and stage 2? Right here’s a fast rundown: Your drone enters failsafe upon dropping radio sign. By default, it could simply drop to the bottom, however with Rescue Mode, it would try to return residence.
Throughout a failsafe, your drone will first enter Stage 1, pausing briefly (guard time) to see if the sign returns. If not, it progresses to Stage 2, activating Rescue mode to deliver the quad again.
Whereas setting GPS Rescue as your failsafe methodology is useful, it’s not fitted to all environments. As an illustration, it’s not advisable in bando, forests, stadiums, or indoors. Dropping management below a tree or inside a constructing might end result within the drone crashing into obstacles when Rescue mode engages.
When you have no GPS lock when it failsafes, the quad will (ought to) simply drop to the bottom.
What Occurs after Rescue Mode is Activated?
Watch GPS Rescue Mode in motion right here:
Rescue mode entails 5 phases:
- Self Stage: The drone permits Angle Mode and self degree.
- Ascend: The drone climbs to a user-configured altitude.
- Rotate: It turns in the direction of the house course.
- Fly Dwelling: The drone begins its journey again to the launch level. The flight may not be a clean cruise, because the drone would possibly pitch forth and again making an attempt to regulate its velocity.
- Descend: As soon as close to the launch level, it begins descending slowly. The descent could be uneven, with the motors making pulsating sounds because the drone tries to decelerate.
- Land: Upon touching the bottom, the drone mechanically disarms, with motors terminating based mostly on influence, not based mostly on altitude.
How you can Cease Rescue Mode
If Rescue mode was activated by way of a swap, regaining full management is so simple as disengaging that swap.
If activated by failsafe:
- If it’s an actual failsafe triggered by a loss radio hyperlink, the pilot should transfer the sticks greater than 30% to regain management after radio hyperlink comes again.
- If the failsafe was triggered manually by way of a swap, merely disengage the failsafe swap — no have to wiggle the sticks.
GPS Rescue Settings Defined
Settings for GPS Rescue mode can be found within the Failsafe tab.
You must tweak the GPS Rescue settings in Betaflight to your particular setup and atmosphere. I extremely advocate visiting the Betaflight wiki to understand a full understanding of what every parameter entails: https://github.com/betaflight/betaflight/pull/11579. The default settings provide a stable place to begin, particularly for five″ freestyle drones.
Right here, I’ll stroll you thru the settings, sharing the values I take advantage of on my 5″ freestyle drone and the reasoning behind every alternative.
Accessing all settings is simple by way of CLI—simply enter get gps_rescue for a complete listing of GPS-related parameters. Nonetheless, adjusting them within the GUI (Failsafe tab) tends to be extra user-friendly.
Altitude Mode: It determines the altitude at which the quad returns residence.
- Most altitude is the very best altitude your quad is flown throughout that flight
- Mounted altitude is only a predefined worth
- Present altitude is no matter peak that the quad is at when GPS rescue mode is activated
The only option varies with every flight’s context and atmosphere. Most altitude generally is a secure possibility, nevertheless it’s not all the time the appropriate possibility. As an illustration, if you happen to was diving a mountain in that flight, you might be losing power climbing again to the max altitude when Rescue mode is activated. When flying over ocean the place there’s no obstructions, fastened altitude could possibly be a great possibility. Use widespread sense, be adaptive to the completely different atmosphere and missions.
Preliminary Climb (meters): The space the quad will climb to this peak above the present altitude, when a rescue is initiated and the altitude mode is ready to Present Altitude. Additionally added when in Max Altitude Mode.
Return Altitude (meters): Solely applies in Mounted Altitude mode. This determines the drone’s return altitude relative to its takeoff level. It needs to be excessive sufficient to clear any obstacles like bushes and buildings however not so excessive that it excessively consumes battery throughout ascent. For my flying spots, which options tall bushes and small hills, I’ve bumped this as much as 50 meters.
Ascend/Descend Fee (meters/second): These charges rely in your atmosphere, climate, and quad’s energy. For my 5″ setup, the defaults ought to work effectively. If utilizing Li-ion packs or low C-rating LiPo, take into account a decrease ascend fee.
Return floor velocity (meters/second): That is the velocity at which the quad travels throughout Rescue. The default 5m/s is 18km/h which I discover approach too sluggish for many drones, I usually double that to 12m/s (43km/h) for micro drones, or 17m/s (60km/h) for five″ and seven″ drones. The quad’s journey course can be extra correct and replace sooner in larger velocity (within the absence of a compass). Don’t set it to decrease than 2m/s or orientation received’t work. Word when getting into this worth in GUI, the unit is completely different than CLI (which is cm/s).
Most Pitch Angle: This setting caps the drone’s tilt angle. The next angle results in extra aggressive returns and better velocity. Possibly helpful for heavier, excessive drag and low authority drones. In windy situations, a better angle could be mandatory for sustaining velocity, particularly for smaller quads. Nonetheless, with an excessively steep angle the drone might lose altitude and crash. Uncertain of what to set? Beginning with the default worth of 40 levels is a secure guess—it’s labored effectively for my 4inch and 5inch setup.
Descend Distance (meters): That is the distance from residence our drone begins to descend. I keep on with the default right here.
Throttle minimal, Throttle most, Throttle hover – these are the min, max and hover throttle values you need to use throughout Rescue mode. Set most so the quad isn’t too quick/jerky (it needs to be above your hover level), set min to maintain the props spinning at an affordable fee (it needs to be decrease than your hover level). I left Throttle Min/Max at default.
To set Throttle Hover, you’ll want to decide an correct worth. Take a look at fly your quad and see at what throttle it hovers (simply sufficient throttle to maintain the quad afloat). Use the “Throttle %” OSD factor to get the precise worth as a substitute of simply guessing. Ideas, the perfect worth ought to trigger the quad to climb a bit whereas in degree mode, if the hover worth is ready too low, the quad will drop early within the rescue – presumably into the water! And the hover throttle worth goes to be barely completely different relies on battery voltage, so that you would possibly marvel, what throttle worth ought to I take advantage of? Nicely you bought to ask your self, at what battery voltage you’re almost certainly going to get a failsafe? It’s acquired to be when the drone is the fartherest from you proper? And you’re most likely simply earlier than half approach via the battery, round 3.8V to three.9V. So use the hover throttle worth at this voltage.
Minimal Distance to Dwelling (meters): If Rescue begins too near residence (inside this minimal distance), the drone will fly away on its present heading till this distance from residence, and begin the traditional Rescue behaviour. I go away this on the default 15 meters.
Minimal Satellites: A minimal of 8 satellites ensures dependable Rescue mode operation. If you happen to take off earlier than the GPS attain the minimal quantity of satellites, it received’t know the precise residence location. Extra satellites imply higher accuracy. I go away this on the default, 8.
Permit Arming With out Repair: This feature offers flexibility by permitting arming with no GPS lock. I allow this for the comfort of check flights, however make sure you get a GPS lock for while you intend to make use of GPS Rescue Mode.
Beware that GPS Rescue WILL NOT work for that flight if you happen to arm earlier than getting a satellite tv for pc lock (as a result of it doesn’t know the house place).
When you have bother getting these many sats (or it takes a very long time), try my tutorial on how one can increase your GPS receiver efficiency. Get a brand new GPS if you happen to should, they solely value $15, an incredible funding for safeguarding your $300 quad!
Sanity Checks: When set to “ON”, it screens GPS Rescue mode situations, for instance:
- Is the GPS nonetheless related to the FC?
- Are we getting a great variety of satellite tv for pc locks?
- Are we at the very least 20 meters away from residence?
- Are we getting nearer to the house, and we didn’t hit an impediment?
If any of those situations usually are not met, it would abort rescue mode and your quad will simply disarm and drop to the bottom. So yea, it’s not perfect in case you are flying over unrecoverable locations like ocean or mountains, however usually, it needs to be on for security causes.
The Betaflight wiki additionally recommends setting Sanity Checks to “Failsafe Solely” in case you are having bother with the choice “On” throughout testing. It turns Sanity Checks off when Rescue mode is activated by a swap however solely turns it on when it’s in failsafe. That is additionally my most popular possibility.
It’s dangerous to show off Sanity Examine solely, you would possibly get an indefinite flyaway. In Betaflight 4.4, there may be now a restrict of 20s of sanity failure even when all sanity checks are off. It’s a security factor. By no means fly with all sanity checks off.
How you can Manually Activate GPS Rescue?
In addition to failsafe, you may have the choice to manually set off GPS Rescue by flipping a swap in your radio transmitter. This characteristic is useful throughout emergencies, corresponding to dropping your approach or encountering points along with your FPV system, permitting your drone to autonomously return residence.
Go to the Modes tab in Betaflight Configurator and assign an AUX channel particularly for GPS Rescue Mode. If you happen to’re new to configuring modes, try my tutorial right here: https://oscarliang.com/betaflight-modes/
Throttle Channel Fallback
Throughout Stage 1 of a failsafe, your drone goes into channel fallback, which means every radio channel is ready to predefined values. It’s sensible to overview these values to make sure security.
By default, the Channel Fallback for Throttle is ready to “Auto,” which reduces the throttle to zero, leads to the motors stopping momentarily in the course of the guard time. This interruption might destabilize the drone earlier than GPS Rescue kicks in, probably failing a sanity examine and inflicting the drone to drop to the bottom.
One answer is to regulate the Throttle Channel Fallback from “Auto” to “Maintain,” sustaining the final throttle worth all through the guard time, stopping motor stalling.
Nonetheless, I personally want setting the throttle to the hover worth, in addition to centering all roll/pitch/yaw channels (set them to 1500 or auto), and prompts the swap for Angle mode. This fashion, the quad ranges itself out when failsafe occurs, earlier than GPS Rescue engages.
Bear in mind, by no means set throttle to zero throughout Stage 1 of failsafe!
How you can Take a look at GPS Rescue
Testing GPS Rescue is a vital step earlier than counting on it in real-world eventualities. Right here’s my method to making sure it really works as anticipated.
The Setup
First, assign a swap in your radio to GPS Rescue to substantiate it may well certainly deliver your drone residence. Ought to something not go in line with plan, flicking the swap off ought to instantly return management to you.
Subsequent, allocate one other swap to Failsafe within the Modes tab. This simulates a full failsafe occasion, identical to dropping RC sign, however in a a lot safer method since you possibly can exit the mode at any time when mandatory utilizing the swap. It’s vital to notice that this setup is strictly for testing functions. When you’re completed, bear in mind to take away Failsafe within the Modes tab.
With the propellers eliminated, head to the Modes tab and make sure that activating the Failsafe swap certainly triggers Rescue mode, throughout which your radio sticks shall be momentarily locked out. Confirm if you happen to can exit failsafe mode and regain management easily.
Whereas bench testing with a USB connection, the Rescue mode indicator may not illuminate as different flight modes do. Nonetheless, so long as the small yellow bar bar strikes into the activation zone, it’s working accurately.
Incorporating GPS-related data into your OSD is useful, offering insights into the drone’s standing. The Flight Mode indicator is especially useful, displaying “RESC” when in Rescue mode, “Air” in fee mode, and “Angle” in angle mode.
Area Testing
For an precise check, select an open space free from obstacles and other people, with mushy grass. Guarantee you may have a legitimate residence level earlier than taking off – ideally the OSD ought to present at the very least 8 satellites or extra.
Take off and fly 50-100 meters away, near the bottom, then set off Failsafe mode utilizing the swap. The quad ought to promptly swap to GPS Rescue mode, indicated by flight mode within the OSD because it adjustments from AIR to RSC.
Take note of the house arrow within the OSD; when it’s pointing up, means you’re heading residence, when pointing down means you’re flying away. Initially, the arrow would possibly level within the unsuitable course in case you are not utilizing a magnetometer, which is regular because it takes 5 to 10 seconds for Betaflight to work out which course it’s heading—simply make sure the drone isn’t flying the exact opposite course after 10 seconds.
You may give up failsafe mode at any time by flipping the swap, regaining full management instantly.
If you happen to select to not disengage, the drone will proceed flying again to the launch level. Upon arrival, it would hover briefly earlier than beginning a sluggish descent, throughout which the motors might pulsate, till it safely lands and disarms mechanically.
You might need to repeat this course of just a few occasions, till you’re assured within the system’s reliability. After thorough testing, don’t overlook to take away Failsafe from the Modes tab.
Ideas and Troubleshooting
Finest Locations to Mount GPS Module
Ensuring your GPS module’s ceramic patch antenna has an unobstructed view of the sky is essential for fast and dependable satellite tv for pc lock-on. Something overlaying it, significantly conductive supplies like carbon fiber, electrical wires, or steel, can considerably weaken the GPS sign.
Avoiding EMI
Electromagnetic interference (EMI) from different electrical parts in your quad may also have an effect on GPS efficiency. Notable sources of RF interference embody HD cameras and video transmitters. To mitigate this, mount your GPS as far-off from these units as doable.
Correct Mounting Orientation
A typical error is mounting the GPS the other way up. The receiver antenna, identifiable by its flat sq. form with a small steel round half within the heart, ought to all the time face upwards. Guarantee no parts impede this aspect. Within the following picture for instance, the ceramic antenna is going through up.
The place to Mount GPS
Listed here are the concerns when mounting your GPS on a quad:
- Tthere’s nothing blocking the GPS unit
- The ceramic antenna is pointing to the sky
- Excellent mounting spots embody the highest of your quad, far-off from VTX and RX antennas
- Stay away from potential radiation sources like HD cameras that may lack correct EMI shielding
Listed here are just a few mounting concepts:
On high of your GoPro/HD digicam.
On high of the body if utilizing an under-slung battery setup.
On a mast to raise the GPS away from the quad. Nonetheless, be cautious of proximity to VTX antennas.
One among my favorite methods is to put in the GPS on the battery strap.
Getting a GPS Lock Sooner
Most GPS modules characteristic a small battery to retailer satellite tv for pc knowledge and time, aiding sooner lock-on. As soon as the GPS has locked onto satellites, it retains their positions for fast reconnection after battery adjustments. In case your GPS persistently takes lengthy to lock, examine if its battery is depleted utilizing a multimeter. Reduce interference as a lot as doable—for example, by relocating a strong VTX, particularly if you happen to’re on a 1.3GHz FPV setup. Climate situations like cloudy days may also influence GPS sign high quality.
For extra recommendations on optimizing BN220 for elevated satellite tv for pc locks, try my devoted tutorial: https://oscarliang.com/gps-settings-u-center/
Recommendations immediately from Betaflight Builders
I like to recommend 10 satellites. [And] Anticipate 30s after [you have] 10 satellites for altitude to stabilise [before taking off].
At all times affirm regular GPS Rescue behaviour firstly of a essential flight by testing with the failsafe swap. Set the swap to right away enter Stage 2. You may enter and go away GPS Rescue by way of the swap with speedy on and off impact. Examine that the quad rotates and flies in the direction of residence and does the appropriate issues earlier than you’re so far-off {that a} true failsafe might happen.
ALWAYS CHECK that the Dwelling Arrow factors immediately again in the direction of residence after takeoff! Typically, if you happen to take off and spin round throughout arming or instantly on takeoff, the quad’s perspective data can turn into corrupted, and the Dwelling Arrow can level the unsuitable approach. It’s finest to arm cleanly and fly away from Dwelling in a straight line at an affordable velocity instantly after takeoff. Watch the Dwelling Arrow fastidiously to make sure it shortly factors again to Dwelling. If the Dwelling Arrow factors the unsuitable approach when a failsafe happens, the GPS Rescue will initially fly off within the unsuitable course, and in some instances, you might lose the quad.
Improper Path in Rescue Mode?
With out a compass, rescue mode ought to nonetheless work because the quads calculate course via GPS knowledge comparability.
At first, your quad could be wandering round and even flying in the direction of the unsuitable course however ultimately it ought to self-correct. With weak GPS connection, it may well take longer to right.
If you’re utilizing a compass and it’s flying the unsuitable course, then possibly there’s one thing unsuitable with the compass, or possibly it’s not calibrated correctly. On this case strive turning off magnetometer in Betaflight and check out once more. If it really works now, it proves your compass is the supply of the issue.
In case your yaw is jerky throughout Rescue mode, your GPS could be updating too slowly (e.g. 1Hz), attempt to enhance it to 5Hz and even 10Hz following this information (solely works on sure GPS modules).
Checking GPS Accuracy (HDOP/PDOP)
HDOP and PDOP are measurements of how correct your GPS is. Decrease values imply higher accuracy. In INAV they use HDOP and in Betaflight 4.5, they use PDOP.
HDOP (Horizontal Dilution of Precision) and PDOP (Place Dilution of Precision) are each measures of GPS accuracy, however they deal with completely different facets. HDOP primarily displays the accuracy of horizontal place (longitude and latitude), whereas PDOP considers the accuracy of each horizontal and vertical positioning (latitude, longitude, and altitude).
You may show PDOP in Betaflight OSD by getting into set osd_gps_sats_show_hdop = ON within the CLI. Here’s what the worth means:
- 1.0 to 1.5: Glorious accuracy, very steady GPS lock.
- 1.5 to 2.0: Acceptable, minor drifting would possibly happen.
- 2.0 to three.0+: Poor accuracy, vital place drift is widespread.
Extra satellites usually decrease your PDOP/HDOP, enhancing GPS accuracy. Digital interference, particularly from units like GoPro cameras or Wi-Fi, can negatively have an effect on PDOP/HDOP and trigger instability in GPS maintain mode.
Keep away from Softserial
Keep away from utilizing Softserial for GPS Rescue because it’s too sluggish. You might use it to show GPS associated data on the OSD, nevertheless it’s merely not dependable sufficient for GPS Rescue. It’s finest to make use of a {hardware} serial port (any TX and RX pins on the FC), and set baudrate to at the very least 57600.
Not Getting GPS Lock
Interference out of your quad’s electronics, such because the VTX, telemetry-equipped radio receivers, and even wires carrying vital present, can hinder your GPS’s capacity to lock onto satellites. If you happen to’re going through difficulties reaching a GPS lock, take into account the next steps:
- Energy the Flight Controller (FC) by way of USB to examine if it powers the GPS module. If not, transfer the GPS module’s energy connection to a unique pad on the FC that will get energy from the USB port.
- Isolate the FC’s Energy Provide: Powering solely the FC with out the VTX can assist you get a faster GPS lock. However, it’s advisable to mount your GPS so far as doable from each the VTX and RX antennas to reduce potential interference.
- Shielding Electrical Wires: shielding wires that conduct vital present can mitigate interference. These wires can act like antennas, probably disrupting GPS indicators.
GPS satellites function on two frequencies, L1 1575.42MHz and L2 1227.60MHz. Consequently, a 1.3GHz FPV setup would possibly intervene along with your GPS. Nearly all of pilots use 5.8GHz, which usually avoids this downside. Nonetheless, given the weak GPS sign—originating from satellites in house—even robust close by indicators may cause interference. Thus, positioning the GPS module away from any transmission sources is essential.
Working GPS wires below the VTX may cause points, significantly if the VTX lacks ample RF shielding. This RF noise can compromise GPS performance. For instance, the Avatar VTX V1 was recognized to trigger GPS issues when wires are routed beneath it. A possible repair entails grounding the VTX’s shielding. Alternatively, shielding the wires between the GPS and FC—and making certain they’re grounded—would possibly provide an answer.
I attempted to defend wires with foil in certainly one of my builds, then related the foil to a floor pad on the FC. After wrapping it with fabric tape to stop short-circuiting the body, I observed minimal enchancment. Whereas some have reported constructive outcomes with this modification, it’s price exploring if different simple options are unavailable.
Didn’t Activate GPS After Updating Betaflight
If you happen to’re unable to allow GPS after flashing the most recent Betaflight model, it’s doable that some options together with GPS had been excluded from the compiled firmware – a brand new characteristic referred to as Cloud Construct System.
To confirm if that is the issue, enter the next command within the CLI:
characteristic gps
Ought to the CLI reply with “gps not accessible,” it signifies that the GPS performance was not included in your FC’s Betaflight firmware. To resolve this, you’ll have to reflash your FC. This time, make sure that the GPS possibility is chosen within the Cloud Construct system throughout compilation: https://oscarliang.com/flash-update-betaflight/#Cloud-Construct-System
Understanding GPS Coordinates Precision
When displaying GPS coordinates within the OSD, you’re supplied with choices to decide on the variety of decimal locations proven—at present, solely 4 and seven decimal choices can be found. This choice immediately influences how precisely you possibly can pinpoint a location on a map based mostly on the GPS knowledge.
The “Decimal Levels” Wikipedia web page offers an in depth desk evaluating diploma precision to bodily distance:
decimal locations levels distance ------- ------- -------- 0 1 111 km 1 0.1 11.1 km 2 0.01 1.11 km 3 0.001 111 m 4 0.0001 11.1 m 5 0.00001 1.11 m 6 0.000001 11.1 cm 7 0.0000001 1.11 cm 8 0.00000001 1.11 mm
It’s essential to distinguish between accuracy and precision on this context. The GPS might show a excessive diploma of precision (variety of digits), however not all decimal locations might mirror true accuracy. Which means whereas your GPS can report coordinates to a really advantageous decision, the precise accuracy—how shut these coordinates are to the true location—might differ.
Edit Historical past
- Oct 2018: Tutorial creation.
- Aug 2020: Updates for GUI and CLI parameter adjustments, addition of throttle settings.
- Feb 2023: BF4.4 replace with auto-landing characteristic.
- Mar 2024: BF4.5 replace.
- Apr 2025: up to date
