Servers by jDrones

100 Km/h low altitude hold ..which Lidar?


(khaled) #1

Hi

I’m trying to enhance the current performance of the conventional high wing trainer used to train falcons for speed … by flying low and fast pulling a lure behind … normally in 400m competition you can see the falcon literally skimming the ground like a foot or two above the ground … When I fly the plane that low and at that speed … actually there is no room for error … a fraction of second and I’m crashed … so if I can manage to use a Lidar with the Pixhawk to take that job off my shoulder so I don’t have to hold that low altitude manually … very exhausting and tiring … because I train many falcons … so it is has to be done so many times per training session …

After some research I’ve found this Lightware SF02 in the description it says that it is lightweight , fast and accurate … so the ability to keep low altitude 5 meters above the ground at a speed around 100 Km/h is crucial …

Could someone please help me if there are better solutions to get this done … as I can see that thread is already since 2014 … so I’m sure a lot has been accomplished already …

Your help is greatly appreciated …

Thanks a lot

Khaled


(Matej Miljko) #2

For low altitude you might be fine, or even better off with a ultrasonic rangefinder, lidar has a much noisier return(grass - ground etc.) so the altitude estimate above high grass is all over the place, if you are planning to fly above water then forget lidar but sonar usually gives a return.

Lidar measures a line while sonar returns the closest value of an area, so if you are pitched nose down you would be receivingthe measurement behind (tho, i believe ardupilot compensates for the angle you still don’t get the measurement under the plane) you while with sonar you will get the closest value.

Lidar has a much faster rate of measurement, 100+ times more per second but sonar is much more affordable.


(ppoirier) #3

Lidar, Sonar… why not Radar ? :wink:

If money and weight was no object, I would go with this: https://www.robotsinsearch.com.au/products/airborne-radar-system/micro-radar-altimeter/smart-micro-airborne-radar-standard
I suspect that sonar cannot efficiently ‘‘push’’ a soundwave @ 100 km/h.
Alternatively, a Lidar looking forward-down @ 45 degree angle with an IMU for pitch angle compensation , (or mounted on a micro gimbal) could read an average ground & obstacle distance so you can get 300 millisec reaction time at 10 Meter height.


(khaled) #4

So you’re saying that the sonar is less sensitive but not fast enough, while the Lidar is much faster but too sensitive leading to wrong readings… but I need the high speed 100km/h … do you know of any sonar that is fast enough to hold 5 m altitude at 100 km/h … and we always fly in the desert over sand … if it will make a difference …

Thanks a lot

Khaled


(L.D. ) #5

This sounds like a really cool project!

Take a look at the LW20 on the LightWare.co.za website. This tiny LiDAR module can update very fast and includes smoothing algorithms to make the readings stable over grass and rough terrain. The integration with ArduPilot is still a bit limited as ArduPilot can’t access all the features built into the LW20. However, LightWare is hoping to extend support for these features in the near future. You can contact the info@ email address listed on the LightWare website for more details and direct support from one of the engineers.

FYI - Ultrasonic doesn’t work at high speeds because the speed of sound is too slow to pick up a reliable signal. Radar is much bigger and heavier than LiDAR.


(Karthik A) #6

Is this sensor already integrated inside the Ardupilot library?
The SMS Airborne RADAR has some really good specifications.


(ppoirier) #7

That would be interesting but I suspect the price of such a sensor makes it out of reach for most of us


(Karthik A) #8

But it would be worth the price if its made compatible to the Ardupilot. Anyone here tried or willing to? I can help them with the hardware…


(ppoirier) #9

Well, in that case I suggest you contact @tridge


(Karthik A) #10

There is one more sensor from Continental ARS 408 which is expensive but very reliable and accurate. @tridge Some ideas, sir?


(Steve Zeets) #11

@khaled_abobakr I can confirm that the LW20 sensor works great!! We have flown at 2m AGL over 2m tall, dense grass using Ardupilot in Auto Mode and it flew along the tops at high speed with no issues.

Best,
Steve


(khaled) #12

This is really good to hear … I was about to lose hope … Could you please tell me if it is a straight forward process I mean the connection of the sensor to the Pixhawk and configuring it.??

I also greatly appreciate sharing the version of the arduplane used …

Thanks a lot

Khaled


(cala2) #13

It´s possible to fly with Lidar and arduplane now, or only for land?, from what vers?


(Steve Zeets) #14

I just followed the instructions in the Ardupilot Wiki and documentation from Lightware.
Using the latest version.


(Karthik A) #15

Thats amazing work, buddy. What speeds were u flying at? can u point me to the parameters u changed.


(Kevin) #16

Hi,khaled.I recommend you to have a try this kind of LiDAR.Here is the link: http://www.benewake.com/en/ce30.html


(Pompe Cukor) #17

I wonder after so many responses…Did I miss something??

As far as I am aware, Arduplane does not support lidar/range finder based terrain following. That seems to be what you are after.
All that is supported currently (last I checked) is lidar assisted landing.

It is supported in Arducopter, but not plane. Plane can only do terrain following base on google data, which is 100% no suitable for what you are after.


(Pompe Cukor) #18

I bet this was arducopter not plane…


(Steve Zeets) #19

Hi @pompecukor
Yes, we used Arducopter.
I must have missed that he was wanting to use Arduplane.
We have not tried it with Arduplane, but I’m pretty sure if it worked with Arduplane (not sure, but it sounds like it doesn’t based on what you stated) you would have to gain altitude before turning around as you would lose quite a bit in the turn.

Best,
Steve

Edit: This was posted in the Arduplane forum. Sorry for the confusion.


(khaled) #20

Well …I wanted to use it on a fixed wing high wing balsa trainer … like the super stick … to go 100 KM/h … but if you have a multicopter that can go a 100 km/h at such a low altitude … I think I still can use it … because it would be more convenient for beginner falconers who don’t have the skills of keeping a fixed wing in the air …

So can your multicopter fly at 100 km/h ?? if yes … Please share your setup … that would be greatly appreciated …

Thanks a lot

Khaled