Lidar Lite installed on OctoQuad

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Albums: X8 Project

Comment by rodger roth on September 10, 2015 at 6:46am

hey friend i run dual skywalker 25A 4in1 also but i run a y6 so i dont use all channels , i notice that you mounted yours on bottom have you ever noticed them getting warm /real warm . i also had them mounted between plates so i mounted some comp e waist heat sinks ansd a little 12V fan run it off same battery that runs gimbal not a deal . cant see how you joined them together on battery side 

   do you use anything else with the lidar unit ie:px4flow, sonar and are you satisfied with performance the additional software is it user friendly and do they have an app. I dont expect you to have all my answers but it could only help to ask  one more have you seen the post about guy spinning a mirror around the sensor is there a reason the sensor can not be rotated signal return speed seems fast enought for a complete rotation every 3or 4 seconds thank you for your time to read this 

Comment by Doug Walmsley on September 10, 2015 at 8:43am

Hi Roger,

My 4x1 ESCs are hot glued to the bottom of my CF chassis with metal plates facing down for cooling.  When I run my X8 hard the ESC are very notable warm, almost close to being hot but cool off quickly.  Not had any problem with them coming loose from the hot glue but then again I think I used 190C (375F) Hi-Temp glue sticks.  I wouldn't recommend placing them inside a frame of any kind as ESC need air flow to help cool them as well as reducing thermal insulation of any kind.  Link below shows the X8 with a better view of the ESCs.

http://diydrones.com/photo/20140413-205438?context=user

 

I used to run my X8 and Y6 with Sonar only but phased them out in favor of the LIDAR unit due to it's ground detection at high altitudes than the Sonar units.  The LIDAR units are advertised with accuracies up to 40 meters, but as I tested, that is dependent on ground angles (ie, Obtuse, Acute, or Perpendicular) and material composition (Ie grass, asphalt, dirt, snow, water, etc).  I've seen that most of my altitude errors go away around 25-30 meters and anything above that has increased drop outs/errors. Have not played with px4flow device but understand that using both px4flow and LIDAR for Indoor flying is optimal.  Certainly couldn't hurt if you have room and don't mind added weight and possibly shorter flight time.

 

Mission Planner software allows you to monitor LIDAR data and I often use it to calibrate between LIDAR readings and Baro readings although Baro will change with altitude and temperature changes, and even atmospheric changes which is minimal for most drones as they don't fly but for a short time. LIDAR is the optimal sensor for altitude measurements but may need calibrating  but setting it on a table extending out and over the edge and physically measuring the distance from ground to sensor then adjusting in Mission Planner the offset until you get a accurate reading.  This is how I calibrate my units. 

As for a rotating LIDAR unit, I do not have anything to provide other than it's possible to create a electrical slip ring to allow the LIDAR to be spin circularly in a horizontal or vertical plane, but you will need to be able to pass through the slip ring, power, ground, and signal (Clk & Data) lines.  I think some feel it's easier to use a rotating mirror although that adds another set of issues such as refractivity, reflections strengths (ie mirror quality)/absorption and artifact noise caused by stray signals returning to mirror/sensor at different times.  There's discussion on DIYdrones about this but I have no interest in testing or developing this as I plan to not use this concept for spatial avoidance in or outdoors. I use mine exclusively for altimeter and terrain following.

Comment by Doug Walmsley on September 10, 2015 at 8:51am

Roger, If you are interested in a slip ring assembly, I would recommend this URL from Adafruit.

https://www.adafruit.com/products/736

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