With a range in excess of 100m and able to measure over water, the SF11/C is the most cost effective laser altimeter for drones on the market today. Compatibility with Pixhawk and derivative flight controllers and its multiple interfaces including serial, I2C, analog and USB make the SF11/C the easiest plug-and-play solution for altitude holding, terrain following and safe landing.
The SF11/C was developed to handle the unpredictable real-world conditions that sensors face when attached to a drone. Environmental factors including vibration, wind, noise, temperature fluctuations and extreme contrasts in lighting from brilliant sunshine to pitch dark are all managed by the SF11/C, and whilst all this is going on, the SF11/C measures to rapidly changing terrain, giving stable results over wet and dry surfaces without producing false readings.
Tests conducted by the Center for Research into Ecological and Environmental Modeling at the University of St Andrews in Scotland demonstrated the abilities of the SF11/C over wetlands and open water. Their requirement for consistent results under these difficult conditions were easily met by the SF11/C, contributing to important conservation work.
An important characteristic of the SF11/C is its long measuring range. This is especially useful during changes of roll or pitch angle. Data from the IMU is used to correct for geometric effects during such maneuvers, but this only works correctly when there is valid measurement data from the laser. The long measuring range of the SF11/C makes this possible as you can see from the graph below.
The green line is the roll angle, the purple line is the barometric height referenced to sea level and the red line is the uncorrected, AGL altitude from the SF11/C. During tight turns the measured distance increases significantly but the long range capability of the SF11/C keeps the ground clearly in view.
More details about the SF11/C can be downloaded from the website. The SF11/C is manufactured by LightWare Optoelectronics (Pty) Ltd based in South Africa. LightWare has been designing and manufacturing laser altimeters for the drone market for 5 years and is committed to providing high quality products to the industry. The official distributors in the USA are Parallax and Acroname.
Special thanks go to the dev team for their contributions to the driver software and Tridge for his tireless and occasionally incendiary flight testing ;).
Comments
Hi LD,
Not to rush you, but I'm very anxious to get my problem with the SF11/C solved asap. Can you please post the next step or two? The company I work for hopes to integrate a LIDAR unit into our production drone and we'd like to use this unit if we can get it to work accurately.
Hi LD,
I'm following along and am ready for the next step. This is pretty cool, thanks for sharing these secrets :)
Tridge is a big fan of the SF11/C if that gives you a hint. He's tested the performance under extreme outback conditions ;)
Thanks a bunch for your sponsorship LD. Really awesome! ;-)
I'm looking forward to testing and using the gear, and of course getting so addicted to it I'll need to buy some!
Which one would you recommend for the OBC? I'm leaning towards the SF11 atm for the extra range as we don't need fine accuracy to control landing descents on the quadplane. But then again we don't really run the risk of flying lower than 50m using the GPS/baro either, so the SF10 would work too, and the SF10 50m is enough to avoid terrain as well should the GPS/baro fail.
Hey JB! - Well done for getting through. Please send Nadia an email at info@lightware.co.za. I see they are scheduled to start shipping next week.
Cool!
I will give you some of the hidden commands then you can take a look at what the unit does with these commands. Feel free to post screen shots where you want more information.
All of our products are designed in a modular fashion where each functional group is separated in both hardware and software. Some things are totally automatic, like stuff that happens inside the FPGA, but lots of stuff in each module is configurable through the software interface.
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With the unit communicating through the USB port to our Terminal program you will see the distance measurements immediately that the unit is switched on. By pressing the <space> key you will see the "user menu" area. By pressing the <space> key again you will see live measurements again.
When you have the menu displayed that shows settings the unit is not measuring, so we call this display "static" and this is where settings can be changed. When the unit is running and showing you the distance we have "dynamic" information that lets you know what the unit is doing. Switching between a dynamic screen and a static screen is done using the <space> key.
The static/dynamic structure that is accessible to the user is a sub-set of a much bigger array. To get access to other settings and their corresponding diagnostics we need to unlock the factory features. There is a very sophisticated unlocking mechanism so read carefully:
From the static user menu screen, press the upper case "U" key. This stands for "Unlock".
When prompted to accept the unlock command press the upper case "Y" key. This stands for "Yes".
That's it. You now have access to all the same features that we use here at the factory.
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So where are the other settings? To get access to the other pairs of static/dynamic screens you use the right or left arrow keys. I suggest that you start at the static user screen and press the <right arrow> once. This takes you to a "system" area where there are new settings. Pressing the <space> key takes you to the dynamic system screen that shows you a bunch of diagnostic data. Pressing the <space> again takes you back to the static system screen.
You can repeat this process of <arrow right>, <space>, <space> to see all the available "static menu / dynamic diagnostic" screens until you wrap around back to the user screens again. As long as you don't try to change any settings you can scroll through the different menus and diagnostics without doing any damage.
Please give that a try and see if you can interpret the settings (written in plain English) and the mnemonics that are shown on each of the dynamic screens.
Hey LD buddy!
Long time no hear! Just wondering what the process is to claim those LIDARs for getting through the OBC D2! PM me if you want.
Regards
Hi Laser Developer,
I would most definitely be interested in learning how to troubleshoot my unit, thank you for the offer. Where shall we start?
@Jimmy Underhill - The SF10 family is more accurate than the SF11 family but the outdoor performance of the SF11 is (supposed) to be better than the SF10. Our factory tests and the feedback from other customers doesn't match with your results so I have to assume that there might be a fault with your unit.
Obviously we can repair the unit under warranty for you. However, there is always the possibility that once back at the factory we may not be able to repeat the problem as you have described it. This does happen sometimes so we have built into the SF11 a whole bunch of diagnostics that make it relatively easy to isolate a problem, and if it is not major, to reconfigure the unit to work correctly.
If you are interested in digging deeper into the inner workings of the SF11 then I can tell you how to unlock the diagnostic features and walk you through an analysis of the data to find exactly where the unit may be failing. I'm happy to do this on an open forum so that other interested people can share in the experience.
I have been doing extensive testing of the SF11/C and a SF10/B that I had previously. I am finding that the SF10 is much more accurate than the SF11, and in fact, the SF11's accuracy is pretty poor comparatively.
I noticed that inside my shop both lidars function very close, and the SF11 is just as accurate as the SF10. However, as soon as I take a step outside into the sunlight, the SF11's readings artificially drop by about 30-40%, if I walk into shade the values become accurate again.
Does anyone else notice this issue with the SF11 and sunlight? Is my unit defective?
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