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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 organising GPS Rescue Mode, testing it, and I’ll additionally share some tips about enhancing its efficiency and troubleshooting widespread points.
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Why GPS Rescue is a Recreation-Changer
Betaflight’s default failsafe motion is dropping the quad to the bottom. Now, with the most recent GPS Rescue Mode, your drone can return near its launch level and land by itself! That is extremely helpful for long-range flights. Truthfully, I’ve misplaced depend of what number of occasions GPS Rescue has saved my drones.
Choosing the Proper GPS Module
High Performer – HGLRC M100 Mini
Smallest Value Having GPS – GOKU GM10 Nano V3
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.
I even have good expertise with the BN-220 (on common over 20 satellites inside a few minutes). But, it’s geared up with the older M8 chip, that means it usually takes longer to lock on to satellites in comparison with the newer M10 chips. In case you are struggling to get first rate efficiency with this GPS, you possibly can strive optimizing the settings as proven right here.
Get the BN-220 right here:
In case you’re taken with a GPS module with an onboard compass, Flywoo has choices, though it’s not crucial for Betaflight’s GPS Rescue mode to work. The modules listed above ought to suffice for Betaflight customers.
Get the BN880 right here:
Era of GPS Chip
Most GPS modules for FPV drones use both an M8 or M10 chip. M10 chips are newer and supply higher efficiency, able to connecting concurrently to 4 World GNSS techniques (GPS, Galileo, Glonass, and Beidou). This ends in quicker lock-ons and connections to extra satellites, particularly in areas with interference or restricted sky view. Regardless of their superior efficiency, M10 items aren’t way more costly than M8 items, making them an economical 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 typically the results of manufacturing unit tuning to make sure optimum frequency. All these antenna have a nominal tuned frequency, however are sometimes impacted by building, elements location and soldering. Inserting small nicks within the centre of the lengthy edges, or corners, can positive 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), it’s not a should for GPS Rescue mode. Nevertheless, having a barometer can enhance altitude management. Simply keep in mind, if you happen to’re making use of conformal coating for water resistance, keep away from masking 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 could possibly be useful.
Is a Compass Vital?
A compass (as often known as magnetometer in Betaflight) is for figuring out instructions.
Some GPS modules supply built-in compass, which will be related to the FC by way of 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 information.
Actually, an improperly calibrated compass would possibly trigger extra points than it solves. In my checks, Rescue mode labored completely positive with no 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 out there 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 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 only option for a steady and dependable connection.
Some flight controllers, just like the Speedybee F405, characteristic 4V5 pads. These are primarily the identical as 5V pads however have the additional advantage of drawing energy from USB. That is notably helpful for these occasions when the GPS is taking some time trying to find satellites. Through the use of 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. Observe that some FCs would possibly supply 5V pads powered by USB however beneath totally different labels; examine with a multimeter if not sure.
Learn how to Setup GPS in Betaflight
GPS Rescue mode in Betaflight is repeatedly evolving, so it’s essential to make use of the most recent firmware model for brand spanking 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 is perhaps 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 varied baud charges: 9600, 19200, 38400, 57600, 115200. In case you are not sure what baudrate your GPS module helps, deciding on AUTO normally works. If not, 57600 or 115200 are widespread charges in GPS modules.
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 reinforce positioning accuracy.
- Save and Reboot.
After organising, the GPS indicator on the high of the configurator ought to mild up, indicating communication with the FC. A purple icon means GPS is speaking to the FC however with no lock, and a yellow icon signifies a profitable GPS lock.
If the GPS indicator stays off, examine for
- GPS will not be powered? Strive plugging in battery?
- Incorrect parameters, for example, flawed baud fee or protocol.
- Incorrect wiring, strive swapping TX and RX.
Learn how to 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 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. In case 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 no less than 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, often known as a “chilly begin”. Subsequent begins are typically 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 you need to check this inside the home, attempt to get near the home windows with the antenna pointing to the sky.
You will notice GPS associated info beneath the GPS tab, the place it reveals the standing of your lock, your GPS coordinates and site on a map, verifying the accuracy of your GPS lock.
LED Indicators
On most GPS such because the BN220, BN180 and BN880, there are two LED indicators, labelled “TX” (normally blue) and “PPS” (normally purple).
Flashing blue (TX) signifies UART connection. Whether it is off, then the GPS 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’ll flash 5 occasions a second.
Flashing purple (PPS) signifies the 2D/3D repair standing of the GPS. If “PPS” is off you then don’t have a repair but.
When it will get a 3D repair, the purple LED on the BN-220 module ought to blink (along with the blue LED).
OSD
You possibly can show GPS information within the OSD. Try this tutorial about Betaflight OSD in case you are not accustomed to 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 factor in your OSD. 6-8 is the minimal for rescue mode to work, the extra the higher. Your GPS coordinates can even get extra correct while 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 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
After you have GPS setup and acquired a lock, go to the radio’s telemetry web page, choose “Uncover new sensors”. Some GPS associated new sensors ought to seem together with GPS coordinates. This solely works in case your radio system helps Telemetry – comparable to ExpressLRS and Crossfire.
This lets you log GPS coordinates in your radio, it permits you to hold observe of the final identified place of your plane. This may be useful for trying to find the misplaced quadcopter if you happen to can’t see the coordinates in your DVR.
Testing Angle Mode
Betaflight’s GPS Rescue mode depends on Angle mode — a self-leveling flight mode — to stabilize the drone. Subsequently, it’s important to make sure Angle mode is functioning 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. Keep 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 possibly can trim the accelerometer within the Configuration tab to attenuate it (however unlikely to fully get rid of it so don’t fear).
Additionally, be aware of the throttle place throughout hover. This worth can be helpful when organising Rescue mode later.
Enabling GPS Rescue Mode in Failsafe
Navigate to the Failsafe tab within the Betaflight Configurator. In case you can’t discover this tab, be sure to’ve enabled the “Skilled Mode” choice on the high of the display (subsequent to the Replace Firmware button).
Beneath Stage 2, choose GPS Rescue. Now, in case your drone enters failsafe, it’ll 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 might simply drop to the bottom, however with Rescue Mode, it’ll 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 carry the quad again.
Whereas setting GPS Rescue as your failsafe technique is helpful, it’s not suited 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 end result within the drone crashing into obstacles when Rescue mode engages.
You probably 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:
- Ascend: The drone climbs to a predetermined altitude or the utmost altitude reached throughout that flight.
- Rotate: It turns in the direction of the house route.
- Fly Dwelling: The drone begins its journey again to the launch level. The flight may not be a easy cruise, exhibiting some lateral actions because it navigates dwelling, however it’ll ultimately arrive.
- Descend: As soon as close to the launch level, inside a 5x5m space, 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 mechanically disarms, with motors terminating based mostly on impression, not based mostly on altitude.
Learn how to Cease Rescue Mode
If Rescue mode was activated by way of 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 by way of 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 important to 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 supply a stable 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 alternative.
Accessing all settings is simple by way of 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.
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
- Mounted 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 could be a secure choice, however it’s not all the time the best choice. As an illustration, if you happen to was diving a mountain in that flight, you would be losing vitality climbing again to the max altitude when Rescue mode is activated. Be adaptive to the totally different atmosphere and missions.
Preliminary Climb (meters): The gap the quad will climb, 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 Mounted Altitude mode. This determines the drone’s return altitude relative to its takeoff level. It must 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 hills, I’ve bumped this as much as 50 meters.
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 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 too sluggish, I doubled that to 10m/s which is 36km/h. The quad’s journey route could be extra correct and replace quicker in larger velocity (within the absence of a compass). Don’t set it to decrease than 2m/s or orientation received’t work. Observe when coming into this worth in GUI, the unit is totally different than CLI (which is cm/s).
Most Pitch Angle: This setting caps the drone’s tilt angle. The next angle results in extra aggressive returns and better velocity. Perhaps helpful for heavier, excessive drag and low authority drones. In windy situations, the next angle is perhaps 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 properly for my setup.
Descend Distance (meters): That is the distance from dwelling our drone begins to descend. I persist with 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 must be above your hover level), set min to maintain the props spinning at an affordable fee (it must be decrease than your hover level). I left Throttle Min/Max at default.
To set Throttle Hover, that you must decide an correct worth. Check fly your quad and see at precisely what throttle it hovers (simply sufficient throttle to maintain the quad afloat), actually each quad is totally different. Use the “Throttle %” OSD factor to get the precise worth as an alternative of simply guessing. Based on information within the pull request, “the right worth ought to trigger the quad to climb a bit whereas in stage mode… If these values are set too low, the quad will drop early within the rescue – presumably into the water!”.
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 depart this on the default 15 meters.
Minimal Satellites: A minimal of 8 satellites ensures dependable Rescue mode operation. In case 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.
Permit Arming With out Repair: This selection supplies flexibility by permitting arming with no GPS lock. I allow this for the comfort of check flights, however make sure you get a GPS lock for while you intend to make use of GPS Rescue Mode.
Beware that GPS Rescue WILL NOT work for that flight if you happen to arm earlier than getting a satellite tv for pc lock (as a result of it doesn’t know the house place).
You probably have bother 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 if you happen to should, they solely value $15, a terrific 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 a superb variety of satellite tv for pc locks?
- Are we no less than 20 meters away from dwelling?
- Are we getting nearer to the house, and we didn’t hit an impediment?
If any of those situations will not be met, it’ll abort rescue mode and your quad will simply disarm and drop to the bottom. So yea, it’s not ideally suited in case you are flying over unrecoverable locations like ocean or mountains, however usually, it must be on for security causes.
The Betaflight wiki additionally recommends setting Sanity Checks to “Failsafe Solely” in case you are having bother with the choice “On” throughout testing. It turns Sanity Checks off when Rescue mode is activated by a change however solely turns it on when it’s in failsafe. That is additionally my most popular choice.
It’s dangerous to show off Sanity Test completely, 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.
Learn how to Manually Activate GPS Rescue?
Apart from failsafe, you have got the choice to manually set off GPS Rescue by flipping a change in your radio transmitter. This characteristic turns out to be useful throughout emergencies, comparable to shedding your manner 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 case 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 clever 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 in the course of the guard time. This interruption might destabilize the drone earlier than GPS Rescue kicks in, probably failing a sanity examine and inflicting the drone to drop to the bottom.
One answer is to regulate the Throttle Channel Fallback from “Auto” to “Maintain,” sustaining the final throttle worth all through the guard time, stopping motor stalling.
Nevertheless, I personally choose setting the throttle to the hover worth, in addition to centering all roll/pitch/yaw channels, and interesting Angle mode. This manner, the quad ranges itself and doesn’t ascend or descend when failsafe occurs, earlier than GPS Rescue engages.
Keep in mind, by no means set throttle to zero throughout Stage 1 of failsafe!
Learn how to Check 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 certainly carry your drone dwelling. 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, similar to shedding RC sign, however in a a lot safer method since you possibly can exit the mode at any time when crucial utilizing the change. 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 be sure that activating the Failsafe change certainly triggers Rescue mode, throughout which your radio sticks can 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 helpful, 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 other people. Make sure the OSD reveals a ample variety of locked satellites earlier than arming.
Take off and fly in a straight line for 100-200 meters, then set off Failsafe mode utilizing the change. The quad ought to promptly change to GPS Rescue mode—observe this transition within the OSD’s flight mode show.
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 flawed route, which is regular because it takes a number of seconds for Betaflight to work out which route it’s heading—simply make sure the drone isn’t flying the exact opposite route.
You possibly can give up failsafe mode at any time by flipping the change, regaining full management instantly.
In case you select to not disengage, the drone will proceed flying again to the launch level. Upon arrival, it’ll hover briefly earlier than beginning a sluggish descent, throughout which the motors might pulsate, till it safely lands and disarms mechanically.
Repeat this course of a number of 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 masking 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 gadgets as potential.
Correct Mounting Orientation
A standard 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 dealing with up.
Placement Methods
Make sure that there’s nothing blocking the GPS unit always. Ultimate mounting spots embrace the highest of your quad, far-off from VTX and RX antennas, and away from potential radiation sources like HD cameras missing correct shielding. Listed below are a number of 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.
Getting a GPS Lock Quicker
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, examine if its battery is depleted utilizing a multimeter. Reduce interference as a lot as potential—for example, by relocating a strong VTX, particularly if you happen to’re on a 1.3GHz FPV setup. Climate situations like cloudy days may also 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/
Options straight from Betaflight Builders
I like to recommend 10 satellites. [And] Look ahead to 30s after [you have] 10 satellites for altitude to stabilise [before taking off].
At all times verify regular GPS Rescue behaviour at the beginning of a important flight by testing with the failsafe change. Set the change to right away enter Stage 2. You possibly can enter and depart GPS Rescue by way of the change with rapid on and off impact. Test that the quad rotates and flies in the direction of dwelling and does the best issues earlier than you might be so far-off {that a} true failsafe might happen.
ALWAYS CHECK that the Dwelling Arrow factors straight again in the direction of dwelling after takeoff! Generally, if you happen to take off and spin round throughout arming or instantly on takeoff, the quad’s perspective info can turn into corrupted, and the Dwelling Arrow can level the flawed manner. 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 flawed manner when a failsafe happens, the GPS Rescue will initially fly off within the flawed route, and in some circumstances, it’s possible you’ll lose the quad.
Improper Course in Rescue Mode?
With out a compass, rescue mode ought to nonetheless work because the quads calculate route by way of GPS information comparability.
Initially, your quad is perhaps wandering round and even flying in the direction of the flawed route however ultimately 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 flawed route, then perhaps there’s one thing flawed with the compass, or perhaps 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 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).
Keep away from Softserial
Keep away from utilizing Softserial for GPS, because it solely helps as much as 19200 baud fee, and with 9600 baudrate the GPS is just not dependable sufficient for GPS options. It’s greatest to make use of a {hardware} serial port (any TX and RX pins on the FC), and set baudrate to no less than 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 case you’re dealing with difficulties reaching a GPS lock, think about the next steps:
- Energy the Flight Controller (FC) by way of USB to examine if it powers the GPS module. If not, transfer the GPS module’s energy connection to a 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 will help 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 attenuate 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 intervene 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 robust close by alerts could cause interference. Thus, positioning the GPS module away from any transmission sources is essential.
Working GPS wires beneath the VTX could 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 supply an answer.
I attempted to defend wires with foil in one in every of my builds, then related 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 optimistic outcomes with this modification, it’s price exploring if different simple options are unavailable.
Didn’t Activate GPS After Updating Betaflight
In case you’re unable to allow GPS after flashing the most recent Betaflight model, it’s potential that some options together with GPS had been excluded from the compiled firmware – a brand new characteristic referred to as Cloud Construct System.
To confirm if that is the issue, enter the next command within the CLI:
characteristic gps
Ought to the CLI reply with “gps not out there,” 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 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—presently, 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 supplies 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 positive decision, the precise accuracy—how shut these coordinates are to the true location—might 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.
