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
we use cannon mk 5diii and 5dsr
I believe you trigger cannon cameras with any switch connected with shutter cable.
@Jason - What camera do you have? Do you have any specs on the shutter triggering?
@laser Developer so I have played around with alarm and i have triggered it but I need VOLTAGE TRIGGERED SWITCH of some sort to trigger the shutter.
I am not a electronics guy and I have no idea about buffer or level translators to get to it work!
can someone point me in the right direction?
I dont want to build one just buy something small and light connect it solder the wires and done
voltage i was reading was 3.3v is that correct?
help thanks
ok I am very busy at work at the moment and wont be able to test until next week. Once I figure it out I will update my progress thanks
@Jason - The bue wire on pin 5 of the main cable is the analog/alarm output. In the main menu you configure it for alarm mode and set the required trigger distance. Once the distance goes below this set point, the voltage on the blue wire goes high.
Without knowing how your shutter system works, the idea would be to hardwire it to the alarm signal. If it requires a different actuation voltage then you might need a buffer, level translator or relay to drive the shutter.
@Laser delevoper thanks for the info MMI mode would be nice for my type of work, I will play with the HMI mode to see if i can get to work as i want to. It could be useful. How do i connect the shutter/alarm to the laser?
@cala that is good idea but how do i trigger the shutter at each waypoint or height with the laser? laser developer said i can only trigger at one spot?
i thought the waypoint uses gps to do that? I do not how to use waypoints with the pixhawk yet so i am a bit confused on how to set-it up
Jason: another idea, if you set vertical waypoints and use terrain data to allow sf11 read altitude? http://ardupilot.org/copter/docs/terrain-following.html#setting-up-...
and camera trigger in each waypoint?
@Jason - yes, you could change the alarm set point through the serial or I2C port if the feature was to be included in the Ardupilot code.
The SF11/C has two different modes of operation. When you set it up on the ground you can use the USB port and input settings using the menus. This is HMI (human-machine-interface) mode where the data is formatted to make it easy to read using any terminal emulation program. Settings entered are saved in flash memory so they automatically take effect when the unit is connected to the flight controller.
The second mode of operation is MMI (machine-machine-interface) and this mode is available through the serial port and the I2C port. During normal operation the live distance is read by ArduPilot through one of these ports. It also has access to the settings but any changes would need to be transmitted from the flight controller to the SF11/C in order to take effect.
So, if you want a single set point to trigger the alarm then it can be entered through the USB port before flight and it will work without any input from ArduPilot. If you want to update the alarm distance during flight then additional code would be required in the flight controller.
As a final thought, all of this can be done through a separate WiFi or BlueTooth converter that accepts serial data and streams it to a terminal emulation program running on a laptop. In this case it would be possible to manually update the settings whenever you wanted.
I hope that answers your question :).
@Laser Developer thanks for the info are you saying it can do it if i add something on the pixhawk/Ardupilot?
Or did i miss read that last sentence? changing the alarm / trigger on the fly is not an option i needed to be preset before i take-off.
can you take me through the steps on how to trigger the alarm/trigger? it might be usual for 360 panoramas
thanks
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