How you can Setup GPS Rescue in Betaflight (FPV Drone Return to House)

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Betaflight GPS Rescue mode is just like “Return to House” on a DJI drone. This function is designed to fly your FPV drone again to its launch level and land it routinely 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 tips about enhancing its efficiency and troubleshooting frequent points.

Why GPS Rescue is a Sport-Changer

Betaflight’s default failsafe motion is dropping the quad to the bottom. Now, with the newest 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 depend of what number of instances GPS Rescue has saved my drones.

How you can Select the Greatest GPS?

Listed here are the issues when choosing a great GPS for Rescue mode:

• M10 GPS is the very best.
• 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 largest GPS you’ll be able to comfortably slot in your drone – greater GPS comes with greater antenna and it’s higher for sign.
• In case your GPS doesn’t reliably provide you with greater than 10 satellites outside, 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 Value Having: GOKU GM10 Nano V3

Smallest Value Having: FlyFishRC M10 Mini

Smallest Value 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.

Era of GPS Chip

Most GPS modules for FPV drones use both an M8, M9 or M10 chip. M10 chips are the latest and provide the very best efficiency, able to connecting concurrently to 4 International GNSS techniques (GPS, Galileo, Glonass, and Beidou). This ends in sooner lock-ons and connections to extra satellites. Regardless of their superior efficiency, the worth of M10 GPS is just 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 unit tuning to make sure optimum frequency. Some of these antenna have a nominal tuned frequency, however are sometimes impacted by building, elements location and soldering. Putting 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 stress, and whereas many flight controllers include one built-in, e.g. the BMP280 (such because the Speedybee F405 V4 and RushFPV F722 V2). Barometer shouldn’t be crucial for Rescue mode, however it may well enhance altitude estimations accuracy, ends in higher altitude management and extra dependable landings. Simply bear in mind, for those who’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 price. In case your flight controller doesn’t have one, including a module with a barometer could possibly be useful.

Is a Compass Obligatory?

A compass (as often called magnetometer in Betaflight) is for figuring out instructions.

Some GPS modules provide built-in compass, which may be related to the FC through the i2c port (SCL and SDA). Nevertheless, Betaflight Rescue Mode doesn’t require a compass to work, it may well work out its route from GPS information.

In truth, an improperly calibrated compass would possibly trigger extra points than it solves. In my assessments, Rescue mode labored completely advantageous with no compass.

How you can inform if a GPS module has built-in compass? If it has 6 wires or solder pads, it means it has a compass – 5V and GND for energy,  TX and RX is for the GPS, and SCL and SDA (i2c port) are for the compass. If it doesn’t have a compass, then there ought to solely be 4 wires/pads – 5V, GND, TX and RX.

Connecting GPS to Flight Controller

Wiring a GPS module to the flight controller is sort 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/barometer)
• GPS SCL – FC SCL (if GPS has a compass/barometer)

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 only option for a steady and dependable connection.

Some flight controllers, just like the Speedybee F405, function 4V5 pads. These are primarily the identical as 5V pads however have the additional benefit of drawing energy from USB. That is notably useful for these instances when the GPS is taking some time trying to find satellites. By utilizing the USB for energy, you keep away from the danger of your VTX overheating whereas ready on the bottom with a LiPo battery plugged in. It additionally helps the GPS lock sooner because the VTX isn’t transmitting and inflicting interference. Observe that some FCs would possibly provide 5V pads powered by USB however beneath completely different labels; examine with a multimeter if not sure.

How you can Setup GPS in Betaflight

GPS Rescue mode in Betaflight is constantly evolving, so it’s essential to make use of the newest 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 beneath the Different Options part. If GPS all the time deactivates after a reboot, it could be resulting from not deciding on GPS within the Cloud Construct choices throughout firmware flashing.

Subsequent, within the Ports tab, assign GPS to the suitable UART beneath “Sensor Enter.” Betaflight helps numerous baud charges: 9600, 19200, 38400, 57600, 115200. If you’re not sure what baudrate your GPS module helps, deciding on AUTO normally works.

The really helpful baud fee for 10Hz GPS information fee is 38400 or 57600. There may be little to be gained through the use of 115200 with 10hz, however utilizing decrease baud charges scale back the CPU load and are extra immune to electrical noise.

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 House 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 Sort 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 crimson 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

1. GPS shouldn’t be powered? Strive plugging in battery?
2. Incorrect parameters, as an example, fallacious baud fee or protocol.
3. 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 information trade. Seeing a stream of binary information means communication is occurring.

Run the ‘gpspassthrough‘ command within the CLI can reveal any ongoing information trade between the FC and GPS.

Seeing a stream of hieroglyphic binary information characters means communication is occurring. In the event you 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 a minimum of 4 satellites and may 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, often called a “chilly begin”. Subsequent begins are typically faster because the module remembers satellite tv for pc positions (for instance if you change battery).

It’s tougher to get a lock indoor. If you need to take a look at this inside the home, attempt to get near the home windows with the antenna pointing to the sky.

You will note GPS associated info beneath the GPS tab, the place it exhibits 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 crimson).

Flashing blue (TX) signifies UART connection. Whether it is off, then the GPS shouldn’t be sending information 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 instances a second.

Flashing crimson (PPS) signifies the 2D/3D repair standing of the GPS. If “PPS” is off then you definately don’t have a repair but.

When it will get a 3D repair, the crimson LED on the BN-220 module ought to blink (along with the blue LED).

OSD

You’ll be able to show GPS information within the OSD. Try this tutorial about Betaflight OSD in case you are not accustomed to it. You’ll be able to show GPS coordinates, distance and route to dwelling and extra.

To know what number of satellite tv for pc have been acquired, place the gps sats ingredient in your OSD. 6-8 is the minimal for rescue mode to work, the extra the higher. Your GPS coordinates may also get extra correct if you purchase extra satellites.

You may as well 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

Upon getting GPS setup and obtained 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 – reminiscent of ExpressLRS and Crossfire.

This lets you log GPS coordinates in your radio, it means that you can hold monitor of the final identified place of your plane. This may be useful for trying to find the misplaced quadcopter for those who 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 stage floor. Failure to take action would possibly consequence 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 hold the drone completely stationary like a DJI drone would. A slight drift resulting from weight distribution and wind is regular, so long as the drone stays steady. If drifting is noticeable, you’ll be able to trim the accelerometer within the Configuration tab to reduce it utilizing stick instructions on the bottom (however unlikely to utterly get rid of it so don’t fear).

Additionally, be aware of the throttle place throughout hover (with a half discharged battery). This worth will likely be helpful when establishing Rescue mode later.

Disabling Magnetometer

As really helpful by Betaflight Builders, except you might be completely certain that your Magnetometer (aka compass) has been correctly calibrated and is working accurately, in any other case it is best to disable it (within the Configuration tab, beneath Accelerometer and Barometer). Betaflight Rescue Mode doesn’t depend upon Magnetometer so it’s advantageous to disable it.

To examine in case your magnetometer is working, evaluate the compass worth in your telephone (set to point out True North, not Magnetic North), with the heading on Configurator’s most important opening display screen, 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 shouldn’t be 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 reminiscent of 56700 or increased. Reducing PID looptime will depart 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. In the event you can’t discover this tab, ensure you’ve enabled the “Skilled Mode” possibility on the high of the display screen (subsequent to the Replace Firmware button).

Below 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 shedding radio sign. By default, it could simply drop to the bottom, however with Rescue Mode, it would try to return dwelling.

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 technique is useful, it’s not fitted to all environments. As an illustration, it’s not advisable in bando, forests, stadiums, or indoors. Shedding management beneath a tree or inside a constructing might consequence within the drone crashing into obstacles when Rescue mode engages.

In case 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:

1. Self Degree: The drone permits Angle Mode and self stage.
2. Ascend: The drone climbs to a user-configured altitude.
3. Rotate: It turns in the direction of the house route.
4. Fly House: The drone begins its journey again to the launch level. The flight may not be a easy cruise, because the drone would possibly pitch forth and again attempting to regulate its velocity.
5. 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.
6. Land: Upon touching the bottom, the drone routinely disarms, with motors terminating primarily based on affect, not primarily based on altitude.

How you can Cease Rescue Mode

If Rescue mode was activated through a change, regaining full management is so simple as disengaging that change.

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 through a change, merely disengage the failsafe change — 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 easy through CLI—simply enter get gps_rescue for a complete record of GPS-related parameters. Nevertheless, adjusting them within the GUI (Failsafe tab) tends to be extra user-friendly.

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Altitude Mode: It determines the altitude at which the quad returns dwelling.

• Most altitude is the very best altitude your quad is flown throughout that flight
• Fastened altitude is only a predefined worth
• Present altitude is no matter top that the quad is at when GPS rescue mode is activated

The only option varies with every flight’s context and atmosphere. Most altitude is usually a secure possibility, nevertheless it’s not all the time the correct possibility. As an illustration, for those who was diving a mountain in that flight, you may be losing vitality 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 frequent sense, be adaptive to the completely different atmosphere and missions.

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Preliminary Climb (meters): The gap the quad will climb to this top above the present altitude, when a rescue is initiated and the altitude mode is about to Present Altitude. Additionally added when in Max Altitude Mode.

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Return Altitude (meters): Solely applies in Fastened Altitude mode. This determines the drone’s return altitude relative to its takeoff level. It ought 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.

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Ascend/Descend Charge (meters/second): These charges rely in your atmosphere, climate, and quad’s energy. For my 5″ setup, the defaults ought to work nicely. If utilizing Li-ion packs or low C-rating LiPo, contemplate a decrease ascend fee.

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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 route can be extra correct and replace sooner in increased velocity (within the absence of a compass). Don’t set it to decrease than 2m/s or orientation received’t work. Observe when getting into this worth in GUI, the unit is completely different than CLI (which is cm/s).

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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 circumstances, the next angle could be crucial for sustaining velocity, particularly for smaller quads. Nevertheless, with an excessively steep angle the drone might lose altitude and crash. Not sure of what to set? Beginning with the default worth of 40 levels is a secure wager—it’s labored nicely for my 4inch and 5inch setup.

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Descend Distance (meters): That is the distance from dwelling our drone begins to descend. I stick to the default right here.

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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 ought to be above your hover level), set min to maintain the props spinning at an affordable fee (it ought to be decrease than your hover level). I left Throttle Min/Max at default.

To set Throttle Hover, you have 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 ingredient to get the precise worth as a substitute of simply guessing. Suggestions, the perfect worth ought to trigger the quad to climb a bit whereas in stage mode, if the hover worth is about too low, the quad will drop early within the rescue – probably into the water! And the hover throttle worth goes to be barely completely different is determined by battery voltage, so that you would possibly surprise, what throttle worth ought to I take advantage of? Nicely you bought to ask your self, at what battery voltage you might be most definitely going to get a failsafe? It’s obtained to be when the drone is the fartherest from you proper? And you might be in all probability simply earlier than half approach by means of the battery, round 3.8V to three.9V. So use the hover throttle worth at this voltage.

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Minimal Distance to House (meters): If Rescue begins too near dwelling (inside this minimal distance), the drone will fly away on its present heading till this distance from dwelling, and begin the traditional Rescue behaviour. I depart this on the default 15 meters.

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Minimal Satellites: A minimal of 8 satellites ensures dependable Rescue mode operation. In the event you take off earlier than the GPS attain the minimal quantity of satellites, it received’t know the precise dwelling location. Extra satellites imply higher accuracy. I depart this on the default, 8.

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Enable Arming With out Repair: This feature offers flexibility by permitting arming with no GPS lock. I allow this for the comfort of take a look at flights, however make sure you get a GPS lock for if you intend to make use of GPS Rescue Mode.

Beware that GPS Rescue WILL NOT work for that flight for those who arm earlier than getting a satellite tv for pc lock (as a result of it doesn’t know the house place).

In case you have hassle getting these many sats (or it takes a very long time), take a look at my tutorial on the right way to increase your GPS receiver efficiency. Get a brand new GPS for those who should, they solely price $15, an awesome funding for shielding your $300 quad!

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Sanity Checks: When set to “ON”, it screens GPS Rescue mode circumstances, for instance:

• Is the GPS nonetheless related to the FC?
• Are we getting a great variety of satellite tv for pc locks?
• Are we a minimum of 20 meters away from dwelling?
• Are we getting nearer to the house, and we didn’t hit an impediment?

If any of those circumstances 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 very best in case you are flying over unrecoverable locations like ocean or mountains, however usually, it ought to be on for security causes.

The Betaflight wiki additionally recommends setting Sanity Checks to “Failsafe Solely” in case you are having hassle with the choice “On” throughout testing. It turns Sanity Checks off when Rescue mode is activated by a change however solely turns it on when it’s in failsafe. That is additionally my most well-liked possibility.

It’s dangerous to show off Sanity Test totally, 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 might have the choice to manually set off GPS Rescue by flipping a change in your radio transmitter. This function turns out to be useful throughout emergencies, reminiscent of shedding your approach or encountering points together with your FPV system, permitting your drone to autonomously return dwelling.

Go to the Modes tab in Betaflight Configurator and assign an AUX channel particularly for GPS Rescue Mode. In the event you’re new to configuring modes, take a look at my tutorial right here: https://oscarliang.com/betaflight-modes/

Throttle Channel Fallback

Throughout Stage 1 of a failsafe, your drone goes into channel fallback, that means every radio channel is about to predefined values. It’s smart to evaluate these values to make sure security.

By default, the Channel Fallback for Throttle is about to “Auto,” which reduces the throttle to zero, ends in the motors stopping momentarily through 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 resolution is to regulate the Throttle Channel Fallback from “Auto” to “Maintain,” sustaining the final throttle worth all through the guard time, stopping motor stalling.

Nevertheless, I personally favor 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 change 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 an important 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 change in your radio to GPS Rescue to verify it may well certainly deliver your drone dwelling. Ought to something not go in line with plan, flicking the change off ought to instantly return management to you.

Subsequent, allocate one other change to Failsafe within the Modes tab. This simulates a full failsafe occasion, similar to shedding RC sign, however in a a lot safer method since you’ll be able to exit the mode each time crucial utilizing the change. 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 be certain that activating the Failsafe change certainly triggers Rescue mode, throughout which your radio sticks will likely be momentarily locked out. Confirm for those who 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. Nevertheless, so long as the small yellow bar bar strikes into the activation zone, it’s working accurately.

Incorporating GPS-related info 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.

Subject Testing

For an precise take a look at, select an open space free from obstacles and folks, with gentle grass. Guarantee you might have a legitimate dwelling level earlier than taking off – ideally the OSD ought to present a minimum of 8 satellites or extra.

Take off and fly 50-100 meters away, near the bottom, then set off Failsafe mode utilizing the change. The quad ought to promptly change to GPS Rescue mode, indicated by flight mode within the OSD because it modifications from AIR to RSC.

Take note of the house arrow within the OSD; when it’s pointing up, means you’re heading dwelling, when pointing down means you’re flying away. Initially, the arrow would possibly level within the fallacious route in case you are not utilizing a magnetometer, which is regular because it takes 5 to 10 seconds for Betaflight to work out which route it’s heading—simply make sure the drone isn’t flying the exact opposite route after 10 seconds.

You’ll be able to give up failsafe mode at any time by flipping the change, regaining full management instantly.

In the event you 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 routinely.

It’s possible you’ll need to repeat this course of just a few instances, till you’re assured within the system’s reliability. After thorough testing, don’t neglect to take away Failsafe from the Modes tab.

Suggestions and Troubleshooting

Greatest 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, notably conductive supplies like carbon fiber, electrical wires, or steel, can considerably weaken the GPS sign.

Avoiding EMI

Electromagnetic interference (EMI) from different electrical elements in your quad may also have an effect on GPS efficiency. Notable sources of RF interference embrace HD cameras and video transmitters. To mitigate this, mount your GPS as far-off from these units as potential.

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 elements impede this facet. Within the following picture for instance, the ceramic antenna is going through up.

The place to Mount GPS

Listed here are the issues when mounting your GPS on a quad:

• Tthere’s nothing blocking the GPS unit
• The ceramic antenna is pointing to the sky
• Preferrred mounting spots embrace the highest of your quad, far-off from VTX and RX antennas
• Stay away from potential radiation sources like HD cameras which 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. Nevertheless, 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 function a small battery to retailer satellite tv for pc information and time, aiding sooner lock-on. As soon as the GPS has locked onto satellites, it retains their positions for fast reconnection after battery modifications. In case your GPS persistently takes lengthy to lock, examine if its battery is depleted utilizing a multimeter. Decrease interference as a lot as potential—as an example, by relocating a robust VTX, particularly for those who’re on a 1.3GHz FPV setup. Climate circumstances like cloudy days may also affect GPS sign high quality.

For extra tips about optimizing BN220 for elevated satellite tv for pc locks, take a look at my devoted tutorial: https://oscarliang.com/gps-settings-u-center/

Strategies straight from Betaflight Builders

I like to recommend 10 satellites. [And] Await 30s after [you have] 10 satellites for altitude to stabilise [before taking off].

All the time verify regular GPS Rescue behaviour at first of a essential flight by testing with the failsafe change. Set the change to instantly enter Stage 2. You’ll be able to enter and depart GPS Rescue through the change with quick on and off impact. Test that the quad rotates and flies in the direction of dwelling and does the correct issues earlier than you might be so far-off {that a} true failsafe might happen.

ALWAYS CHECK that the House Arrow factors straight again in the direction of dwelling after takeoff! Generally, for those who take off and spin round throughout arming or instantly on takeoff, the quad’s perspective info can develop into corrupted, and the House Arrow can level the fallacious approach. It’s finest to arm cleanly and fly away from House in a straight line at an affordable velocity instantly after takeoff. Watch the House Arrow rigorously to make sure it shortly factors again to House. If the House Arrow factors the fallacious approach when a failsafe happens, the GPS Rescue will initially fly off within the fallacious route, and in some instances, chances are you’ll lose the quad.

Flawed Path in Rescue Mode?

With out a compass, rescue mode ought to nonetheless work because the quads calculate route by means of GPS information comparability.

At first, your quad could be wandering round and even flying in the direction of the fallacious route however finally 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 fallacious route, then possibly there’s one thing fallacious 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 improve 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’ll be able to 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: Wonderful 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 frequent.

Extra satellites usually decrease your PDOP/HDOP, bettering 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. It’s possible you’ll use it to show GPS associated information 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 a minimum of 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 means to lock onto satellites. In the event you’re going through difficulties reaching a GPS lock, contemplate the next steps:

• Energy the Flight Controller (FC) through USB to examine if it powers the GPS module. If not, transfer the GPS module’s energy connection to a special 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 potential 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 alerts.

GPS satellites function on two frequencies, L1 1575.42MHz and L2 1227.60MHz. Consequently, a 1.3GHz FPV setup would possibly intrude together with your GPS. The vast majority of pilots use 5.8GHz, which usually avoids this drawback. Nevertheless, given the weak GPS sign—originating from satellites in area—even sturdy close by alerts may cause interference. Thus, positioning the GPS module away from any transmission sources is essential.

Operating GPS wires beneath the VTX may cause points, notably if the VTX lacks sufficient RF shielding. This RF noise can compromise GPS performance. For instance, the Avatar VTX V1 was identified 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 one among my builds, then related the foil to a floor pad on the FC. After wrapping it with material tape to stop short-circuiting the body, I seen minimal enchancment. Whereas some have reported constructive outcomes with this modification, it’s price exploring if different simple options are unavailable.

Did not Activate GPS After Updating Betaflight

In the event you’re unable to allow GPS after flashing the newest Betaflight model, it’s potential that some options together with GPS had been excluded from the compiled firmware – a brand new function referred to as Cloud Construct System.

To confirm if that is the issue, enter the next command within the CLI:

function 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, be certain 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 straight influences how precisely you’ll be able to pinpoint a location on a map primarily based on the GPS information.

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 replicate true accuracy. Because of this whereas your GPS can report coordinates to a really advantageous decision, the precise accuracy—how shut these coordinates are to the actual location—might differ.

Edit Historical past

• Oct 2018: Tutorial creation.
• Aug 2020: Updates for GUI and CLI parameter modifications, addition of throttle settings.
• Feb 2023: BF4.4 replace with auto-landing function.
• Mar 2024: BF4.5 replace.
• Apr 2025: up to date