28.1K
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 robotically in a failsafe or when your video feed will get sketchy. On this tutorial, I’m going to stroll you thru organising GPS Rescue Mode, testing it, and I’ll additionally share some recommendations on enhancing its efficiency and troubleshooting frequent points.
Among the hyperlinks on this web page are affiliate hyperlinks. I obtain a fee (at no additional price to you) if you happen to make a purchase order after clicking on certainly one of these affiliate hyperlinks. This helps help the free content material for the group on this web site. Please learn our Affiliate Hyperlink Coverage for extra info.
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 rely of what number of occasions GPS Rescue has saved my drones.
The best way to Select the Greatest GPS?
Listed here are the issues when choosing GPS for Rescue mode:
- M10 GPS is the perfect.
- It Ought to Assist UBLOX protocol, keep away from NMEA protocol because it solely helps 1Hz replace fee and that’s too sluggish.
- Get the largest GPS you possibly can 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 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.
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 perfect efficiency, able to connecting concurrently to 4 International GNSS techniques (GPS, Galileo, Glonass, and Beidou). This ends in quicker 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 unit tuning to make sure optimum frequency. A lot of these antenna have a nominal tuned frequency, however are sometimes impacted by development, elements location and soldering. Putting small nicks within the centre of the lengthy edges, or corners, can superb 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 will not be obligatory for Rescue mode, however it could enhance altitude estimations accuracy, ends in higher altitude management and extra dependable landings. Simply keep 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 price. In case your flight controller doesn’t have one, including a module with a barometer might be useful.
Is a Compass Essential?
A compass (as often known as magnetometer in Betaflight) is for figuring out which route 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 info no matter motion route. And not using a compass, Betaflight estimates heading from GPS information, which will be inaccurate when the drone is drifting (like in a crosswind), inflicting inefficient corrections.
Nevertheless, whereas a compass can improve efficiency, it provides complexity. It requires cautious setup in Betaflight, additional wiring, correct mounting orientation, and calibration. It’s additionally delicate to electrical noise, which might result in inaccurate readings. For most individuals, a compass will not be obligatory until you will have particular necessities.
Some GPS modules have built-in compass: GPS with out compass have 4 wires, whereas these with a compass sometimes have 6 wires. The 2 additional 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 sort of easy. 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 in 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 secure 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 advantage of drawing energy from USB. That is significantly helpful for these occasions when the GPS is taking some time looking for 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 quicker because the VTX isn’t transmitting and inflicting interference. Notice that some FCs would possibly provide 5V pads powered by USB however below completely different labels; test with a multimeter if uncertain.
The best way to 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 below the Different Options part. If GPS at all times deactivates after a reboot, it is perhaps because 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 numerous baud charges: 9600, 19200, 38400, 57600, 115200. In case you are uncertain what baudrate your GPS module helps, choosing AUTO often works.
The advisable baud fee for 10Hz GPS information fee is 38400 or 57600. There’s little to be gained through the use of 115200 with 10hz, however utilizing decrease baud charges scale back the CPU load and are extra proof against electrical noise.
| GPS Information Charge | Baud Charge | CPU Load | Feedback |
| 20Hz | 115200 | Highest | M10 solely; take a look at rigorously! |
| 10Hz | 38400 or increased | Medium | 10Hz and 57600 is advisable for GPS Rescue |
| 5Hz | 19200 or increased | Medium | Okay settings for common use |
| 1Hz-2Hz | 9600 or increased | Least | Too sluggish for clean GPS rescue, OK for easy place/velocity information |
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 reinforce positioning accuracy.
- Save and Reboot.
After organising, the GPS indicator on the high of the configurator ought to gentle up, indicating communication with the FC. A pink 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, test for
- GPS will not be powered? Strive plugging in battery?
- Incorrect parameters, for example, mistaken baud fee or protocol.
- Incorrect wiring, attempt swapping TX and RX.
The best way 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 information alternate. Seeing a stream of binary information means communication is occurring.
Run the ‘gpspassthrough‘ command within the CLI can reveal any ongoing information alternate between the FC and GPS.
Seeing a stream of hieroglyphic binary information characters means communication is occurring. Should you see nothing, there could also be a problem 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 might take a couple of minutes.
While you energy up the GPS module for the primary time in a brand new location, it at all times takes longer to seek for satellites, often known as a “chilly begin”. Subsequent begins are typically faster because the module remembers satellite tv for pc positions (for instance once you change battery).
It’s more durable to get a lock indoor. If it’s a must 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 below 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” (often blue) and “PPS” (often pink).
Flashing blue (TX) signifies UART connection. Whether it is off, then the GPS will not 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’s going to flash 5 occasions a second.
Flashing pink (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 pink LED on the BN-220 module ought to blink (along with the blue LED).
OSD
You possibly can show GPS information within the OSD. Take a look at this tutorial about Betaflight OSD if you’re not conversant in it. You possibly can 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 aspect 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 once you purchase extra satellites.
You may also 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 under is right, which might provide you with an accuracy of about 2.5 meters or much less. It is perhaps oversimplying, however simply consider it as how a lot the drone could 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 – akin to ExpressLRS and Crossfire.
This lets you log GPS coordinates in your radio, it permits you to maintain monitor of the final identified 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. 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 degree floor. Failure to take action would possibly outcome within the drone drifting whereas in Angle mode.
To check Angle mode, attempt 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 maintain the drone completely stationary like a DJI drone would. A slight drift because of weight distribution and wind is regular, so long as the drone stays secure. 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 utterly 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 organising Rescue mode later.
Disabling Magnetometer
As advisable by Betaflight Builders, until you’re completely positive that your Magnetometer (aka compass) has been correctly calibrated and is working appropriately, in any other case it’s best to disable it (within the Configuration tab, below Accelerometer and Barometer). Betaflight Rescue Mode doesn’t rely upon Magnetometer so it’s superb to disable it.
To test in case your magnetometer is working, evaluate the compass worth in your cellphone (set to point out True North, not Magnetic North), with the heading on Configurator’s most important opening display, 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 at all times begins at North, and follows quick actions rapidly however then jumps to another worth, the Magazine will not 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 as a result of CPU intensive nature of Rescue Mode, particularly with excessive baud fee akin to 56700 or increased. Reducing 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, be sure you’ve enabled the “Professional Mode” choice on the high of the display (subsequent to the Replace Firmware button).
Below Stage 2, choose GPS Rescue. Now, in case your drone enters failsafe, it’s going to 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 will simply drop to the bottom, however with Rescue Mode, it’s going to 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. Dropping management below a tree or inside a constructing may outcome 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:
- Self Stage: The drone allows Angle Mode and self degree.
- Ascend: The drone climbs to a user-configured altitude.
- Rotate: It turns in direction of the house route.
- 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.
- Descend: As soon as close to the launch level, it begins descending slowly. The descent is perhaps uneven, with the motors making pulsating sounds because the drone tries to decelerate.
- Land: Upon touching the bottom, the drone robotically disarms, with motors terminating based mostly on affect, not based mostly on altitude.
The best way to 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.
It’s a must to tweak the GPS Rescue settings in Betaflight to your particular setup and setting. I extremely suggest visiting the Betaflight wiki to know a full understanding of what every parameter entails: https://github.com/betaflight/betaflight/pull/11579. The default settings provide a strong place to begin, particularly for five″ freestyle drones.
Right here, I’ll stroll you thru the settings, sharing the values I exploit on my 5″ freestyle drone and the reasoning behind every selection.
Accessing all settings is easy by way of CLI—simply enter get gps_rescue for a complete listing of GPS-related parameters. Nevertheless, adjusting them within the GUI (Failsafe tab) tends to be extra user-friendly.
Altitude Mode: It determines the altitude at which the quad returns dwelling.
- Most altitude is the best altitude your quad is flown throughout that flight
- Fastened 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 setting. Most altitude is usually a secure choice, nevertheless it’s not at all times the fitting choice. As an illustration, if you happen to was diving a mountain in that flight, you can be losing vitality climbing again to the max altitude when Rescue mode is activated. When flying over ocean the place there’s no obstructions, mounted altitude might be choice. Use frequent sense, be adaptive to the completely different setting 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 about to Present Altitude. Additionally added when in Max Altitude Mode.
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 timber and buildings however not so excessive that it excessively consumes battery throughout ascent. For my flying spots, which options tall timber and small hills, I’ve bumped this as much as 50 meters.
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 properly. If utilizing Li-ion packs or low C-rating LiPo, think about 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 manner 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 could be extra correct and replace quicker in increased velocity (within the absence of a compass). Don’t set it to decrease than 2m/s or orientation gained’t work. Notice when coming 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. A better angle results in extra aggressive returns and better velocity. Perhaps helpful for heavier, excessive drag and low authority drones. In windy situations, a better angle is perhaps obligatory 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 guess—it’s labored properly for my 4inch and 5inch setup.
Descend Distance (meters): That is the distance from dwelling our drone begins to descend. I stick to the default right here.
Throttle minimal, Throttle most, Throttle hover – these are the min, max and hover throttle values you wish 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, it is advisable 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 an alternative 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 about 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 surprise, what throttle worth ought to I exploit? Effectively you bought to ask your self, at what battery voltage you’re probably going to get a failsafe? It’s obtained to be when the drone is the fartherest from you proper? And you’re in all probability simply earlier than half manner by 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 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 go away this on the default 15 meters.
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 dwelling location. Extra satellites imply higher accuracy. I go away this on the default, 8.
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 once 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).
In case you have bother getting these many sats (or it takes a very long time), take a look at my tutorial on enhance your GPS receiver efficiency. Get a brand new GPS if you happen to should, they solely price $15, an ideal funding for shielding 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 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 situations should not met, it’s going to abort rescue mode and your quad will simply disarm and drop to the bottom. So yea, it’s not ideally suited 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 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 choice.
It’s dangerous to show off Sanity Examine totally, 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.
The best way to Manually Activate GPS Rescue?
Apart from failsafe, you will have the choice to manually set off GPS Rescue by flipping a swap in your radio transmitter. This characteristic is useful throughout emergencies, akin to dropping your manner or encountering points along 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. Should 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 clever to assessment 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 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 choose 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 manner, 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!
The best way to Check GPS Rescue
Testing GPS Rescue is an important step earlier than counting on it in real-world situations. 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 verify it could certainly deliver your drone dwelling. Ought to something not go based on 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, similar to dropping RC sign, however in a a lot safer method since you possibly can exit the mode at any time when obligatory utilizing the swap. It’s essential to notice that this setup is strictly for testing functions. When you’re completed, keep 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 might 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. 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.
Discipline Testing
For an precise take a look at, select an open space free from obstacles and other people, with smooth grass. Guarantee you will have a sound 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 swap. The quad ought to promptly swap 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 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 possibly can stop failsafe mode at any time by flipping the swap, regaining full management instantly.
Should you select to not disengage, the drone will proceed flying again to the launch level. Upon arrival, it’s going to hover briefly earlier than beginning a sluggish descent, throughout which the motors could pulsate, till it safely lands and disarms robotically.
It’s possible you’ll wish 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
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, significantly conductive supplies like carbon fiber, electrical wires, or metallic, can considerably weaken the GPS sign.
Avoiding EMI
Electromagnetic interference (EMI) from different electrical elements 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 units 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 middle, ought to at all times 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
- Very best mounting spots embody the highest of your quad, far-off from VTX and RX antennas
- Steer clear of 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 digital camera.
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 characteristic a small battery to retailer satellite tv for pc information and time, aiding quicker 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 constantly takes lengthy to lock, test if its battery is depleted utilizing a multimeter. Reduce interference as a lot as attainable—for example, by relocating a strong VTX, particularly if you happen to’re on a 1.3GHz FPV setup. Climate situations like cloudy days also can affect GPS sign high quality.
For extra recommendations on optimizing BN220 for elevated satellite tv for pc locks, take a look at my devoted tutorial: https://oscarliang.com/gps-settings-u-center/
Solutions straight from Betaflight Builders
I like to recommend 10 satellites. [And] Anticipate 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 vital flight by testing with the failsafe swap. Set the swap to instantly enter Stage 2. You possibly can enter and go away GPS Rescue by way of the swap with quick on and off impact. Examine that the quad rotates and flies in direction of dwelling and does the fitting issues earlier than you’re so far-off {that a} true failsafe could happen.
ALWAYS CHECK that the Dwelling Arrow factors straight again in direction of dwelling after takeoff! Typically, if you happen to take off and spin round throughout arming or instantly on takeoff, the quad’s angle info can grow to be corrupted, and the Dwelling Arrow can level the mistaken manner. 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 rigorously to make sure it rapidly factors again to Dwelling. If the Dwelling Arrow factors the mistaken manner when a failsafe happens, the GPS Rescue will initially fly off within the mistaken route, and in some circumstances, it’s possible you’ll lose the quad.
Flawed Route in Rescue Mode?
And not using a compass, rescue mode ought to nonetheless work because the quads calculate route by GPS information comparability.
Originally, your quad is perhaps wandering round and even flying in direction of the mistaken route however finally it ought to self-correct. With weak GPS connection, it could 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 attempt 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 is perhaps 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 give attention to 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 possibly can show PDOP in Betaflight OSD by coming 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 secure 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 sometimes 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. 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 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) by way of USB to test if it powers the GPS module. If not, transfer the GPS module’s energy connection to a distinct 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. Nonetheless, it’s advisable to mount your GPS so far as attainable 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, 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 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 satisfactory 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 guaranteeing they’re grounded—would possibly provide an answer.
I attempted to protect 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 optimistic outcomes with this modification, it’s value exploring if different easy 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 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 choice 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 the moment, solely 4 and seven decimal choices can be found. This choice straight influences how precisely you possibly can pinpoint a location on a map based mostly 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 could show a excessive diploma of precision (variety of digits), however not all decimal locations could replicate true accuracy. Which means that whereas your GPS can report coordinates to a really superb decision, the precise accuracy—how shut these coordinates are to the actual location—could range.
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 characteristic.
- Mar 2024: BF4.5 replace.
- Apr 2025: up to date
