Learn how to Setup GPS Rescue in Betaflight (FPV Drone Return to Dwelling)

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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 tips about enhancing its efficiency and troubleshooting widespread 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. Truthfully, I’ve misplaced depend of what number of occasions GPS Rescue has saved my drones.

Learn how to Select the Finest GPS?

Listed below are the concerns when choosing an excellent 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 gradual.
• Get the most important GPS you may comfortably slot in your drone – greater GPS comes with greater antenna and it’s higher for sign.
• In case your GPS doesn’t reliably offer you 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/

High Performer: GEPRC M1025Q

High 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, however 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 latest and supply the very best efficiency, able to connecting concurrently to 4 International GNSS techniques (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 harm. It’s typically the results of manufacturing unit tuning to make sure optimum frequency. A lot of these antenna have a nominal tuned frequency, however are sometimes impacted by building, parts location and soldering. Inserting small nicks within the centre of the lengthy edges, or corners, can wonderful 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 is just not crucial for Rescue mode, however it may enhance altitude estimations accuracy, leads to 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 supply a built-in barometer for an additional value. In case your flight controller doesn’t have one, including a module with a barometer may very well be helpful.

Is a Compass Obligatory?

A compass (as generally known as magnetometer in Betaflight) is for figuring out instructions.

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

In reality, an improperly calibrated compass would possibly trigger extra points than it solves. In my checks, Rescue mode labored completely wonderful and not using a compass.

Learn how to 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 kind of simple. Merely join it on to any obtainable 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 to 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 the best choice for a steady and dependable connection.

Some flight controllers, just like the Speedybee F405, characteristic 4V5 pads. These are basically the identical as 5V pads however have the additional advantage of drawing energy from USB. That is notably useful for these occasions 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 for the reason that VTX isn’t transmitting and inflicting interference. Word that some FCs would possibly supply 5V pads powered by USB however below totally different labels; test with a multimeter if uncertain.

Learn how to Setup GPS in Betaflight

GPS Rescue mode in Betaflight is repeatedly 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 below the Different Options part. If GPS all the time deactivates after a reboot, it could be attributable to not deciding on 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 numerous baud charges: 9600, 19200, 38400, 57600, 115200. In case you are uncertain what baudrate your GPS module helps, deciding on AUTO often works.

The advisable baud fee for 10Hz GPS knowledge fee is 38400 or 57600. There may be little to be gained through the use of 115200 with 10hz, however utilizing decrease baud charges cut 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 Dwelling Level As soon as to forestall 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 prime of the configurator ought to gentle up, indicating communication with the FC. A pink icon means GPS is speaking to the FC however and not using a lock, and a yellow icon signifies a profitable GPS lock.

If the GPS indicator stays off, test for

1. GPS is just not powered? Strive plugging in battery?
2. Incorrect parameters, as an example, mistaken baud fee or protocol.
3. Incorrect wiring, strive swapping TX and RX.

Learn how to test 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. Should 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 at the least 4 satellites and might take a couple of minutes.

While 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 more durable to get a lock indoor. If it’s important 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 info below the GPS tab, the place it exhibits the standing of your lock, your GPS coordinates and placement 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” (often blue) and “PPS” (often pink).

Flashing blue (TX) signifies UART connection. Whether it is off, then the GPS is just not 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 pink (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 pink LED on the BN-220 module ought to blink (along with the blue LED).

OSD

You’ll be able to show GPS data within the OSD. Try this tutorial about Betaflight OSD if you’re not aware of it. You’ll be able to show GPS coordinates, distance and route to residence and extra.

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

You can even 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 offer you 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 bought 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 – comparable to ExpressLRS and Crossfire.

This lets you log GPS coordinates in your radio, it lets you preserve observe 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. Due to this fact, it’s important to make sure Angle mode is functioning appropriately.

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 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 gained’t preserve the drone completely stationary like a DJI drone would. A slight drift attributable to weight distribution and wind is regular, so long as the drone stays steady. If drifting is noticeable, you may trim the accelerometer within the Configuration tab to attenuate it utilizing stick instructions on the bottom (however unlikely to fully remove it so don’t fear).

Additionally, pay attention to the throttle place throughout hover (with a half discharged battery). This worth might be helpful when establishing Rescue mode later.

Disabling Magnetometer

As advisable by Betaflight Builders, except you might be completely positive that your Magnetometer (aka compass) has been correctly calibrated and is working appropriately, 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 wonderful to disable it.

To test in case your magnetometer is working, evaluate the compass worth in your telephone (set to indicate True North, not Magnetic North), with the heading on Configurator’s major opening display screen, the GPS tab in Configurator, or the Sensors tab debug line 5 in debug mode GPS_RESCUE_HEADING, and test 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 is just not proper.

Keep away from Utilizing 8K/8K

As per builders suggestions, keep away from 8K PID Loop Frequency, use 4K or decrease. That is as a result of CPU intensive nature of Rescue Mode, particularly with excessive baud fee comparable to 56700 or greater. 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. Should you can’t discover this tab, ensure you’ve enabled the “Knowledgeable Mode” possibility on the prime 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 dropping radio sign. By default, it might 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 convey the quad again.

Whereas setting GPS Rescue as your failsafe methodology is useful, it’s not suited to all environments. As an example, it’s not advisable in bando, forests, stadiums, or indoors. Shedding management below a tree or inside a constructing may end result within the drone crashing into obstacles when Rescue mode engages.

If 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 Stage: The drone allows 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 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 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 mechanically disarms, with motors terminating primarily based on impression, not primarily based on altitude.

Learn how to 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.

It’s a must to tweak the GPS Rescue settings in Betaflight to your particular setup and setting. 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 supply a stable start line, 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 residence.

• 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

Your best option varies with every flight’s context and setting. Most altitude is usually a secure possibility, however it’s not all the time the suitable possibility. As an example, for those who was diving a mountain in that flight, you could possibly 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 may very well be an excellent possibility. Use widespread sense, be adaptive to the totally different setting and missions.

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Preliminary Climb (meters): The space 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 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.

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Ascend/Descend Charge (meters/second): These charges rely in your setting, 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, think about 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 means too gradual 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 greater velocity (within the absence of a compass). Don’t set it to decrease than 2m/s or orientation gained’t work. Word when getting into this worth in GUI, the unit is totally 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 situations, a better angle could be crucial for sustaining velocity, particularly for smaller quads. Nevertheless, with an excessively steep angle the drone may 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 effectively for my 4inch and 5inch setup.

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Descend Distance (meters): That is the distance from residence 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 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 want to decide an correct worth. Check fly your quad and see at what throttle it hovers (simply sufficient throttle to maintain the quad afloat). Use the “Throttle %” OSD aspect 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 totally different relies on battery voltage, so that you would possibly marvel, what throttle worth ought to I take advantage of? Properly you bought to ask your self, at what battery voltage you might be more than likely going to get a failsafe? It’s bought to be when the drone is the fartherest from you proper? And you might be in all probability simply earlier than half means 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 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.

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Minimal Satellites: A minimal of 8 satellites ensures dependable Rescue mode operation. Should you take off earlier than the GPS attain the minimal quantity of satellites, it gained’t know the precise residence location. Extra satellites imply higher accuracy. I go away this on the default, 8.

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Enable Arming With out Repair: This selection offers flexibility by permitting arming and not using a 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 for those who arm earlier than getting a satellite tv for pc lock (as a result of it doesn’t know the house place).

If in case you have hassle getting these many sats (or it takes a very long time), try my tutorial on how one can enhance your GPS receiver efficiency. Get a brand new GPS for those who should, they solely value $15, an amazing funding for shielding your $300 quad!

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

• Is the GPS nonetheless linked to the FC?
• Are we getting an excellent variety of satellite tv for pc locks?
• Are we at the 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 best if you’re 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” if you’re 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 Verify fully, you would possibly get an indefinite flyaway. In Betaflight 4.4, there’s 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.

Learn how to Manually Activate GPS Rescue?

Moreover failsafe, you will have the choice to manually set off GPS Rescue by flipping a change in your radio transmitter. This characteristic is useful throughout emergencies, comparable to dropping your means 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. Should you’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, that means every radio channel is about to predefined values. It’s sensible to evaluation these values to make sure security.

By default, the Channel Fallback for Throttle is about to “Auto,” which reduces the throttle to zero, leads to the motors stopping momentarily throughout the guard time. This interruption may destabilize the drone earlier than GPS Rescue kicks in, doubtlessly failing a sanity test 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.

Nevertheless, I personally desire 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!

Learn how to Check GPS Rescue

Testing GPS Rescue is a vital step earlier than counting on it in real-world situations. Right here’s my strategy to making sure it really works as anticipated.

The Setup

First, assign a change in your radio to GPS Rescue to substantiate it may certainly convey your drone residence. Ought to something not go in keeping 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, identical to dropping RC sign, however in a a lot safer method since you may exit the mode at any time when 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 make sure that activating the Failsafe change certainly triggers Rescue mode, throughout which your radio sticks might 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 appropriately.

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 check, select an open space free from obstacles and folks, with gentle grass. Guarantee you will have a sound residence level earlier than taking off – ideally the OSD ought to present at the least 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 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 mistaken route if you’re 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 stop failsafe mode at any time by flipping the change, regaining full management instantly.

Should 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 gradual descent, throughout which the motors could pulsate, till it safely lands and disarms mechanically.

Chances are you’ll need to repeat this course of just a few occasions, 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

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 protecting it, notably conductive supplies like carbon fiber, electrical wires, or metallic, can considerably weaken the GPS sign.

Avoiding EMI

Electromagnetic interference (EMI) from different electrical parts in your quad also can 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 gadgets as attainable.

Correct Mounting Orientation

A typical error is mounting the GPS the wrong way up. The receiver antenna, identifiable by its flat sq. form with a small metallic 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 below 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
• Ultimate mounting spots embody the highest of your quad, far-off from VTX and RX antennas
• Avoid potential radiation sources like HD cameras which may lack correct EMI shielding

Listed below are just a few mounting concepts:

On prime of your GoPro/HD digicam.

On prime 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 in all my favorite methods is to put in the GPS on the battery strap.

Getting a GPS Lock Quicker

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, test if its battery is depleted utilizing a multimeter. Reduce interference as a lot as attainable—as an example, by relocating a robust VTX, particularly for those who’re on a 1.3GHz FPV setup. Climate situations like cloudy days also can impression GPS sign high quality.

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

Strategies 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 verify regular GPS Rescue behaviour at first of a vital flight by testing with the failsafe change. Set the change to instantly enter Stage 2. You’ll be able to enter and go away GPS Rescue through the change with speedy on and off impact. Verify that the quad rotates and flies in the direction of residence and does the suitable issues earlier than you might be so far-off {that a} true failsafe could happen.

ALWAYS CHECK that the Dwelling Arrow factors immediately again in the direction of residence after takeoff! Typically, for those who take off and spin round throughout arming or instantly on takeoff, the quad’s perspective info can grow to be corrupted, and the Dwelling Arrow can level the mistaken means. It’s greatest to arm cleanly and fly away from Dwelling in a straight line at an affordable velocity instantly after takeoff. Watch the Dwelling Arrow rigorously to make sure it shortly factors again to Dwelling. If the Dwelling Arrow factors the mistaken means when a failsafe happens, the GPS Rescue will initially fly off within the mistaken route, and in some circumstances, you might lose the quad.

Mistaken Course in Rescue Mode?

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

Firstly, your quad could be wandering round and even flying in the direction of the mistaken route however finally it ought to self-correct. With weak GPS connection, it may take longer to appropriate.

In case you are utilizing a compass and it’s flying the mistaken route, then possibly there’s one thing mistaken with the compass, or possibly it’s not calibrated correctly. On this case strive turning off magnetometer in Betaflight and take a look at 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 totally 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: Glorious accuracy, very steady GPS lock.
• 1.5 to 2.0: Acceptable, minor drifting would possibly happen.
• 2.0 to three.0+: Poor accuracy, important place drift is widespread.

Extra satellites sometimes decrease your PDOP/HDOP, enhancing GPS accuracy. Digital interference, particularly from gadgets 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 gradual. Chances are you’ll use it to show GPS associated data on the OSD, however it’s merely not dependable sufficient for GPS Rescue. It’s greatest to make use of a {hardware} serial port (any TX and RX pins on the FC), and set baudrate to at the 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 important present, can hinder your GPS’s skill to lock onto satellites. Should you’re going through difficulties reaching a GPS lock, think about the next steps:

• Energy the Flight Controller (FC) through USB to test 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 may also help you get a faster GPS lock. However, it’s advisable to mount your GPS so far as attainable from each the VTX and RX antennas to attenuate potential interference.
• Shielding Electrical Wires: shielding wires that conduct important present can mitigate interference. These wires can act like antennas, doubtlessly disrupting GPS indicators.

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

Operating GPS wires below the VTX could cause points, notably if the VTX lacks ample 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 supply an answer.

I attempted to defend wires with foil in one in every of my builds, then linked the foil to a floor pad on the FC. After wrapping it with fabric tape to forestall short-circuiting the body, I seen minimal enchancment. Whereas some have reported constructive outcomes with this modification, it’s value exploring if different simple options are unavailable.

Didn’t Activate GPS After Updating Betaflight

Should you’re unable to allow GPS after flashing the newest Betaflight model, it’s attainable that some options together with GPS have been excluded from the compiled firmware – a brand new characteristic known 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 obtainable,” 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 may pinpoint a location on a map primarily based 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 could show a excessive diploma of precision (variety of digits), however not all decimal locations could mirror true accuracy. Which means that whereas your GPS can report coordinates to a really wonderful decision, the precise accuracy—how shut these coordinates are to the actual location—could 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