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
@Jason - The SF11/C has an analog output that can also be used as a digital alarm / trigger whenever the distance reads shorter than a preset value. It only activates at one pre-set distance, so for more than one "waypoint" you would need to change the alarm distance on-the-fly which can be done through the serial or I2C ports. This is not something that Ardupilot offers as standard.
hey everybody
my next question or mission
I want to integrate the laser meter with a shutter cable to take a picture at exactly the right height. It is possible??
Kind like waypoint shooting but this uses gps. Mine is on a gimbal and i dont do waypoints we do balocony shots for high rise buildings or vertical waypoints if you like to call it that way. Say 5f then 10F then 15f for an example
can someone point me in the right direction?
Steve, I had issues with Lidar lite and recive a sf11 to test in similar situations and any issue, I fly over crops where shadows are a constant so I hope It has to work over pavement (more flat than crops) better.
Here you can watch some tests: http://diydrones.com/profiles/blogs/sf-11-laser-altimeter-an-useful...
and it's true plug and play :)
@Steve - thanks for the information Steve.
I've used some ToF sensors that were very susceptible to that issue and I've talked to people who have used lidarlite and they said there were issues going from one surface type to another. Just curious if others have had similar issues.
@Steve - this is an interesting question and technically it can be a challenging application but not many people know this. Is there a particular reason why you think it wouldn't work? Do you have experience with other products where this is a problem?
@Jason Smoker - thanks very much for the feedback.
Steve as long there really uneven ground under the laser it works great shade or no shade! i have tested mine up to its max range 120m with great results in shaded areas
Do these work well over pavement? Specifically going from shade to non-shade? Any data?
edge: look how I attached as Laser dev recommends me and results, it's incredible but no need to carry any gimbal, is a vicious to fly with this tool. :)
http://diydrones.com/profiles/blogs/sf-11-laser-altimeter-an-useful...
@edge540T - the ArduPilot software has vertical correction built-in so it's not necessary to use a gimbal. If you need any help you can contact the team at ardupilot.org or send a message to info@lightware.co.za. Good luck ;).
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