added sf45 as a seperate rangefinder #3448

Claudio-Chies · 2024-11-11T10:48:32Z

Adapted and updated the documentation for the SF45 Rangefinder
Added it to sensors instead of a chapter in collision prevention, although thats the main usecase.
marked the Lanbao Sensor as EOL, as i cant find it available anymore, and some sellers marked it as EOL

Relevant PR's

SENS: SF45: Improved Datahandling and fixes PX4-Autopilot#23918

en/computer_vision/collision_prevention.md

hamishwillee · 2024-11-13T04:37:51Z

This is IMO ready when your PR is ready - thanks very much!!! I did some restructure to make the new rangefinder doc a sub-doc - that allows us to expand the structure if we want in future.

Note that the build error can be ignored. It happens because I moved one of the image files alongside the other, and the existing translations depend on that location. This will be fixed after merging by crowdin.

hamishwillee · 2024-12-04T01:28:29Z

en/sensor/sf45_rotating_lidar.md

+## Debugging / Common problems
+If you are experiencing start-up issues, jerky movements or a lot of com errors displayed with `lightware_sf45_serial status` this could mean that you are having power issues.
+
+The Sensor seems to be quite sensitive in regard to whether he gets enough power.
+According to the Datasheet, the sensor needs 300 mA of current at 5V, whereby the stock cable is fairly long and can cause problems where the voltage drops too much.
+So it's important to make sure that the cable is kept as short as possible.
+As an alternative, you can power the SF45 via a separate Step-down converter from battery voltage. With this approach, you're able to eliminate all power-related issues.


Suggested change

## Debugging / Common problems

If you are experiencing start-up issues, jerky movements or a lot of com errors displayed with `lightware_sf45_serial status` this could mean that you are having power issues.

The Sensor seems to be quite sensitive in regard to whether he gets enough power.

According to the Datasheet, the sensor needs 300 mA of current at 5V, whereby the stock cable is fairly long and can cause problems where the voltage drops too much.

So it's important to make sure that the cable is kept as short as possible.

As an alternative, you can power the SF45 via a separate Step-down converter from battery voltage. With this approach, you're able to eliminate all power-related issues.

## Debugging / Common problems

Start-up issues, jerky movements, or a lot of coms errors displayed with `lightware_sf45_serial status` could mean that the sensor is not getting enough power.

According to its datasheet, the sensor needs 300 mA of current at 5V.

The supplied cable is fairly long and when connected to a 5V supply, the voltage at the rangefinder may have dropped below the required level.

One mitigation/alternative is to power the SF45 via a separate step-down converter from battery voltage, ensuring that there are 5V across the rangefinder itself.

@Claudio-Chies Where you say

The stock cable is fairly long and can cause problems where the voltage drops too much, so it is important to keep the cable is kept as short as possible.

Do you mean this is supplied with a cable but it is too long? Are you then proposing that the user gets a different cable that is shorter, or cuts this one back?

Depending on your answer I'll modify the suggestion above.

Yes, the stock cable is 35cm, when using that cable, then supplying power from an BEC is recommended.

OK, I have modified the #3448 (comment) and will merge. Please check it is right now.

i've added a commit where i specify that we are talking about the 5V supply from TELEM ports, and not any 5V supply

hamishwillee · 2024-12-11T03:04:10Z

I've separately added a PR the lanbao, so that this isn't mixed in with this PR about #3487

github-actions · 2024-12-11T03:27:05Z

No flaws found

hamishwillee · 2024-12-11T03:27:05Z

en/sensor/sf45_rotating_lidar.md

+
+<video src="../../assets/hardware/sensors/lidar_lightware/sf45_plotjuggler.mp4" width="720" controls></video>
+
+In order to generate this kind of plot you will need to add the following Reactive Scripts to PlotJuggler.


What is a Reactive Script? Is there a good link to a definition we can add here for someone wanting to learn more?

Reactive scripts are Lua scripts inside plot juggler, sadly the documentation for PlotJuggler is severely lacking. So there's no good source on what it actually is.

hamishwillee · 2024-12-11T03:27:42Z

en/sensor/sf45_rotating_lidar.md

+In order to generate this kind of plot you will need to add the following Reactive Scripts to PlotJuggler.
+If you save these scripts and then add new data, you will see a new timeseries called `obstacle_distance_xy`, which is the same as is displayed in the video.
+
+**Global code, executed once:**


Is it bleedingly obvious how you execute/add these scripts? If not then we need to either add a link to instructions or explain how here. Up to you which.

Sadly not, i'll add a screenshot, and mention where the setting is.

hamishwillee · 2024-12-11T03:29:11Z

en/sensor/sf45_rotating_lidar.md

+
+Debugging problems with distance sensors is much easier if you can plot the [OBSTACLE_DISTANCE](https://mavlink.io/en/messages/common.html#OBSTACLE_DISTANCE) message in an x-y plot, because this lets you directly see the orientation of the measurement in respect of the drone.
+
+The video below shows how you can view such a plot in PlotJuggler.


I assume this is a live view as per https://docs.px4.io/main/en/debug/plotting_realtime_uorb_data.html ?

Can we link to this too?

no, currently its just a log replay. i found a way you can adapt the script to use for realtime debugging with it, i can write the code for it in collision prevention in a seperate PR

hamishwillee · 2024-12-11T04:08:47Z

Can we get the video on PX4 youtube and link it. The file is not huge, but obviously it is cheaper if authors don't have to download it for local editing

Claudio-Chies · 2024-12-11T09:15:48Z

a video of the SF45. the plotjuggler layout or of the drone flying?

Claudio-Chies force-pushed the pr-sf45 branch from e14bb3c to 4270c05 Compare November 11, 2024 10:51

Claudio-Chies mentioned this pull request Nov 11, 2024

SENS: SF45: Improved Datahandling and fixes PX4/PX4-Autopilot#23918

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Claudio-Chies requested a review from hamishwillee November 11, 2024 10:52

Claudio-Chies force-pushed the pr-sf45 branch from 4270c05 to 4376433 Compare November 11, 2024 12:12

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hamishwillee force-pushed the pr-sf45 branch 2 times, most recently from 2d2246c to a32bec6 Compare November 20, 2024 04:01

Claudio-Chies force-pushed the pr-sf45 branch from b561ee8 to 3b6e6d0 Compare December 3, 2024 08:01

hamishwillee reviewed Dec 4, 2024

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hamishwillee mentioned this pull request Dec 11, 2024

Lanbao CM8JL65 is discontinued #3487

Merged

Claudio-Chies and others added 7 commits December 11, 2024 14:06

added sf45 as a seperate rangefinder

146f261

Improve structure

6839c01

shrink image

1ed9654

Added information on power related issues

6270da6

Update en/sensor/sf45_rotating_lidar.md

ec9240f

specified that the 5V supply is meant from the FMU

c790496

added info and scripts for obstacle_distance debugging with plotjuggler

43c85a9

hamishwillee force-pushed the pr-sf45 branch from 1dbe41f to 43c85a9 Compare December 11, 2024 03:06

Minor subedit

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hamishwillee reviewed Dec 11, 2024

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added sf45 as a seperate rangefinder #3448

added sf45 as a seperate rangefinder #3448

Claudio-Chies commented Nov 11, 2024 •

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hamishwillee commented Dec 11, 2024

Claudio-Chies commented Dec 11, 2024


		<video src="../../assets/hardware/sensors/lidar_lightware/sf45_plotjuggler.mp4" width="720" controls></video>

		In order to generate this kind of plot you will need to add the following Reactive Scripts to PlotJuggler.


		Debugging problems with distance sensors is much easier if you can plot the [OBSTACLE_DISTANCE](https://mavlink.io/en/messages/common.html#OBSTACLE_DISTANCE) message in an x-y plot, because this lets you directly see the orientation of the measurement in respect of the drone.

		The video below shows how you can view such a plot in PlotJuggler.

added sf45 as a seperate rangefinder #3448

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added sf45 as a seperate rangefinder #3448

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Claudio-Chies commented Nov 11, 2024 • edited Loading

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hamishwillee commented Dec 11, 2024

Claudio-Chies commented Dec 11, 2024

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