Basically here is the site it is a short range inferred radar that could be used for a failsafe in case your uav gets close to the ground. However it is slightly bulky but that can be easily modified because it was made for parking cars. This includes a servo with an inferred transceiver or receiver and transmitter separate, i haven't really looked into it very far. If you are board and want to serf the web go to "Hackaday.com". Thats where i found the range finder and is a great place to hack if you want to.
I am looking for a sensor for UAV assisted landings on grass and dense vegetation. I am looking for ranges up to 15 meters and down to a few cm. The speed can be 40 km/h on landings or below. The sensor will move over grasss in up to 40 km/h. Will your maxSonar products work? Can you send me a unit for evaluation in my UAV?
MaxBotix Inc., has released the new XL-MaxSonar products. This product line should solver the problems above relate to noise and not enough acoustic output power. The XL-MaxSonar line has fully automatic real-time background calibration, much higher acoustic output power, greatly improved real-time noise rejection, centimeter resolution, longer distance range measurement, and for some models real-time analog envelope output and various analog hardware gains from 250 to 4000. These improvements result in virtually noise free distance readings for most users. The XL-MaxSonar is avaialbe in both indoor and ourdoor versions.
So I was thinking if you had decent relative altitude - perhaps a pressure sensor - one could:
1. descend slowly from WP 1 to WP 2 (the landing strip) with a gentle climb out and go around.
2. decrease the target altitude slightly.
3. repeat 1 & 2 until the plane touched down. Since the lowest altitudes occur in the target area, touchdown should occur in the target area.
Caveats, avoid obstacles, and observers in the go-around region.
@Dincer. Thanks for your input. I spent some time fine tuning my nunchuck-headtracker-xbee code the last week, but I had no time for cleaning up and finish commenting. I intended to finish this prior to bring up a new discussion about that part of my project here on DIYdrones. The post will include a description of my setup, the codes, and a video of the system up and running including headtracker calibration, frontview/bottomview buttons action, double button shutter for digital camera, and the joystick as trim to center the pan/tilt camera where you wish.
If you don't mind to wait for a few days, I suppose I shall be done during next weekend. The code for the headtracker will be loaded onboard the airframe in a spare ArduPilot I intend to use also for parsing GPS NMEA (for my OSD) and send downlink data through xbee pro 868. In the end, the ground headtracker/nunchuck will be controlled by an Arduino Pro Mini (Sparkfun). Its code will also integrates 2 cell lipo voltage monitoring with sporadic buzzer alarm at 3.3v/cell and continuous 3.0v/cell. since I received the mini only recently, I had no time to prepare the connections. Until then, the headtracker/nunchuck will work on an arduino duemilanove.
So please check back at the end of coming weekend for the complete post (I hope I get everything done until then!)
yes that maybe an idea... getting some readings first and avaraging them as a reading fix... can u post your smoothing code here so that we can check with ours... i am not very good at programming and usually waste my hours writing and debugging few sentences... :) i also use nunchuck in my project and i have a working code moving 2 servos with nunchuck accelerometer at roll and pithch axes... if u want i can post it here for you...
Hi Dincer. If you want to smooth the readings, better do it with an average in your code. It is what I've basically done to smooth my head tracker based on Nunchuck Wii game handle. In the case of the EZ1, I think averaging 6-12 readings should be better than no averaging for grassy surface ranges. But empirical testing will give the ideal number of readings for average. One could even imagine an average rate varying with the data spread.
i have the same sensor and planning to use it for autonomous landing assist... i did almost the same tests with u but i used raw values at analog0 of my arduino. i also added a small cylinder 1inch long to narrow the receipt angle... however my ez1 reads 0-320 raw readings.. i wrote a simple code to read the raw value and light a rgb led... val>100 green, 100>val>50 blue and val>50 red... i tested indoors only wandering around my home and had mostly consistent readings. i even tried to smooth the reading by adding a 0.1u cap between analog0 and sensor but this proved to be better first, but after some minutes the cap heats and reaings get to be erroneaus about 20 inches. i am also convinced that i can use this sensor as an assist in autonomous landing...
The EZ1 has a 20Hz reading rate, but reading can also be triggered/controlled through a pin. It has 3 simultaneous outputs (serial 9600, analog 10mV/inch, and PWM 147uS/inch).
Here's the specification sheet.
how quickly does the EX1 update the distance? I tried using Lego NXT ultrasonics a while back with my UGV but they were just simply too slow for anything usefull - so I switched to scanning IR (its an indoor vehicle) which works very well. I have been thinking of hacking one of those laser rangefinders for golfers into a ground proximity detector since I did not think US would be up to the job...
Comments
I am looking for a sensor for UAV assisted landings on grass and dense vegetation. I am looking for ranges up to 15 meters and down to a few cm. The speed can be 40 km/h on landings or below. The sensor will move over grasss in up to 40 km/h. Will your maxSonar products work? Can you send me a unit for evaluation in my UAV?
UFO_MAN
Please click this linkt to view more information about the XL-MaxSonar products. http://www.maxbotix.com/uploads/Small_Industrial_Ultrasonic_Sensors...
Best regards,
Scott Wielenberg
Technical Support & Sales
of MaxBotix Inc.
Phone: (218) 454-0766 Ext. 2
Fax: (218) 454-0768
Email: scott@maxbotix.com
Web: www.maxbotix.com
MaxBotix, MaxSonar, EZ0, EZ1, EZ2, EZ3, EZ4 and WR1 are trademarks of MaxBotix Inc.
Did the smoothing code work?
UFO_MAN
1. descend slowly from WP 1 to WP 2 (the landing strip) with a gentle climb out and go around.
2. decrease the target altitude slightly.
3. repeat 1 & 2 until the plane touched down. Since the lowest altitudes occur in the target area, touchdown should occur in the target area.
Caveats, avoid obstacles, and observers in the go-around region.
If you don't mind to wait for a few days, I suppose I shall be done during next weekend. The code for the headtracker will be loaded onboard the airframe in a spare ArduPilot I intend to use also for parsing GPS NMEA (for my OSD) and send downlink data through xbee pro 868. In the end, the ground headtracker/nunchuck will be controlled by an Arduino Pro Mini (Sparkfun). Its code will also integrates 2 cell lipo voltage monitoring with sporadic buzzer alarm at 3.3v/cell and continuous 3.0v/cell. since I received the mini only recently, I had no time to prepare the connections. Until then, the headtracker/nunchuck will work on an arduino duemilanove.
So please check back at the end of coming weekend for the complete post (I hope I get everything done until then!)
Here's the specification sheet.
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