Hi guys!

I recently had a chance to test out YDLIDAR X2, that could be a cheaper alternative to RPLIDAR. Here are some of the characteristics of this unit:

Parameter Value
Scanning range 360°
Range 0.1-8m
Range resolution 2% of distance
Scan frequency 5-8Hz
Range frequency 3000Hz
Max current 500mA
Laser wavelength 775-795nm
Laser power 3-5mW
Price ~89 USD

I only tested it for an indoor SLAM (with ROS and Google Cartographer) getting a result as you can see above

I think this sensor might be an interesting option for obstacle avoidance (although I'm not sure if the 7Hz update rate is good enough). If anyone thinks adding this LiDAR to ArduCopter obstacle avoidance supported devices then let me know and I'll look into implementing it!

If you'd like to know more details then check out my blog post: https://msadowski.github.io/ydlidar-x2-review-ros-cartographer/ , where I also link to the repository with my Cartographer setup.

If you have any questions about the unit let me know and I'll answer them. I'm also happy to run some tests for the community!

Views: 637


3D Robotics
Comment by Chris Anderson on May 24, 2019 at 9:25am

Great to see this review. I've been using the RPLidar products for a while and while I like them, their Python support is weak. I don't want to have to use ROS (overkill for my projects). What do you think of the YDLidar Python libraries?

Comment by Stefan Mürzl on May 24, 2019 at 11:12pm

There is a 3rd party project which supports ydlidar

https://github.com/lakshmanmallidi/PyLidar3

Comment by Mateusz Sadowski on May 25, 2019 at 6:59am

Chris I tried to find any YDLIDAR python libraries but apart from the one linked by Stefan I couldn't locate any.  The PyLidar3 doesn't seem to support YDLIDAR X2 just yet.

The oficial SDK for YDLIDAR seem to be this one and it's written in C++.


3D Robotics
Comment by Chris Anderson on May 25, 2019 at 2:01pm

Thanks Stefan! Looks well done

Comment by d j on May 28, 2019 at 9:40am

@Mateusz Sadowski

Interested to buy YDLIDAR X2 and install it on roof top of my car, if fit to work in outdoor to build basic, obstacle avoidance safety system.

Tell me what number of points can be scanned for a single full

360° turn

and at RPM speed it rotates

Frankly speaking I would like to employ mirrors control system known from laser/ led projectors to build 2D forward looking scanning array.

Let me know your opinion.

Comment by Mateusz Sadowski on May 29, 2019 at 12:40am

You would install it on a real car or an R/C one? If it's a proper car then I suggest you don't use this LiDAR, it's a maker quality tool not suitable for safety applications.

If my calculations are correct you should get about between 400-500 points in each sweep

The servers the data at 7Hz, therefore the rotation rate should be the same. Here are some datasheets: http://www.ydlidar.com/download

For 2D forward looking array you can look into Risle Prism scanner (https://www.thorlabs.com/images/tabimages/Risley_Prism_Scanner_App_...). Off the shelf LiDAR employing that is Livox Mid-40.

In other news, the X2 price has been reduced to $69, making it most probably the most affordable LiDAR ever made.

Comment by d j on May 29, 2019 at 4:16am

@Mateusz Sadowski

I would like to experiment with automatic parking system for a real car, pretested in R/C one as a testbed.

This unit is intended for indoor use but in theory can be operated in outdoor under no rain, no frost conditions.

I would like to test parallel parking and your video shows I can succeed.

To make this unit to look sideways, at lower altitudes ( if mounted on car's roof top) I can combine it with basic servo to flip it sideways.

A little more complicated approach than laser beamer turned lidar, mounted 50cm above car's roof top.

Let me know your opinion.

"400-500 points in each sweep

from

Chart 1 YDLIDAR X2 Product Parameter

"
Item Min. Typical Max. Unit Remarks
Range
frequency - 3000 - Hz 3000 times/s
Scan
frequency 5 - 8 Hz PWM or Voltage
regulation
Distance
Range 0.10 - >8 m Indoor

How to calculate RPM for this unit from the above data ?

Range frequency - 3000 - Hz 3000 times/s  stays for what ?

Theory behind Risley Prism Scanner is really great but it would take me a month to master it.

My choice is affordable laser beamer coming with 2 prisms or 2 rotating mirrors

and I would like to replace standard laser with laser optics + scanner coming from the above lidar

Comment by Mateusz Sadowski on May 29, 2019 at 7:00am

The scan frequency is ~7Hz therefore we can assume that LiDAR needs to rotate once to collect a single scan. This means that the rotations speed is 7RPS * 60 = 420 RPM

Also if we are collecting 3000 samples per second and the LiDAR does 7 rotations per second then a single scan should contain around 430 samples.

Personally for this type of problem I would go for multiple ToF cameras like Intel Realsense. The hardware cost is much higher but if you use 4 of those cameras you can probably cover most of the field of view you could be interested in and you minimize the hardware complexity.

With any single plane LiDAR to make sure that you capture everything around the car you would need to sweep it (as you mentioned) which will increase the mechanical complexity and depending on your approach also the software will become a bit more sophisticated

Comment by d j on May 29, 2019 at 7:39am

Thank you.

If I understand correctly, this lidar pulsates at 5-8Hz max. if static or rotating, so is very very slow , why ?

"Range frequency - 3000 - Hz 3000 times/s

or "Range frequency - term stays for what ?

"Also if we are collecting 3000 samples per second

how can we collect 3000 samples per second if this lidar pulsates at 7Hz ?

"Also if we are collecting 3000 samples per second and the LiDAR does 7 rotations per second then a single scan should contain around 430 samples.

how did you get RPM from datasheet ?

Ok, I can use twin cameras to get 3D depth data but his lidar worked fine in your video, so I need it for tests.

Mechanical complexity can be easily tacked installing 2 lidars, one looking to the left and another to the right.

I am watching hundreds of drivers, having problems to park his/her car parallel, so any aid is better than nothing.

Planar projection error is negligible (in my self-testing).

I would like this lidar to connect wirelessly to smartphone's run app supporting automatic parking in parallel

Sorry for my basic questions about RPM and Range frequency - 3000 - Hz 3000 times/s

since no info can be extracted from datasheet

What data format is supported

distance + angle + time stamp ?

Comment by d j on May 31, 2019 at 9:08am

@Mateusz Sadowski

I would prefer single optical path version of lidar to get better resolution and sensitivity

from http://www.eaibot.com/

G4 16m scanning range       - stays for what ?

scanning rate 9000times/s  - sounds  realistic

X4    11nMeter Scanning Range  - stays for what ?

No support by a manufacturer

I give up

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