YDLidarX2_Driver

Driver for the YDLIDAR X2 low-cost 2-D LiDAR connected by USB serial; outputs one full scan per revolution.

Processing

Connects at 115200 baud to DeviceName and decodes the scan packets with the YDLIDAR driver code (MIT License).
Inverted is passed to the YDLIDAR driver. The X2 measures its angle clockwise; Inverted = true (default) turns it into a counter-clockwise positive angle, which follows the coordinate convention of this toolkit (ROS REP-103: X forward, Y left, angle 0 on +X). Only the angle of each point is changed (2π − θ); the points stay in the measurement (time) order, so the angle decreases along the array. Set it to false only when the raw clockwise angle is needed.
StartAtZeroAngle rotates the array so that it starts at the point closest to angle 0. The points keep the measurement (time) order and are not sorted by value; use a sorting component for that. FixedOutputSize keeps the same number of points per revolution.

Typical outputs: angle_num → DataViewer.input_0; angle → DataViewer.input_1; distance_in_m → laser_scan_to_xyz_points.dist_points.

angle (rad or deg, in [-pi, pi)), distance_in_m (Float64) and distance_in_mm (Integer32) have angle_num elements (at most 2048).
Points out of the measuring range (below 0.05 m or above 64 m) are kept with distance 0. All outputs carry the time at which the scan was received.

Tested with X2; other YDLIDAR variants may work at your own risk.
Version 1.01: AngleSort was renamed StartAtZeroAngle, and Inverted was added with the default true. Version 1.0 output the clockwise angle; set Inverted = false to match data recorded with it.

[1] EAI (YDLIDAR), YDLidar-SDK (bundled in 3rdparty/YDLidar-SDK). https://github.com/YDLIDAR/YDLidar-SDK — Used for: sensor connection and scan acquisition (CYdLidar).

Name	Default	Description
`DeviceName`	`COM1`	Serial device of the LiDAR (COMx on Windows, /dev/tty* on Linux).
`FixedOutputSize`	`false`	If true, every revolution is output with the same number of points.
`StartAtZeroAngle`	`false`	If true, the output starts at the point closest to angle 0 (cyclic shift, measurement order kept); otherwise the driver order is kept.
`AngleUnit`	`radian`	Unit of the angle output. Options: `radian`, `degree`.
`Inverted`	`true`	Passed to the YDLIDAR driver. true (default): counter-clockwise positive angle (ROS REP-103), because the X2 measures clockwise. false: raw clockwise angle of the X2. Either way the points keep the measurement (time) order.

Name	Description
`angle_num`	Number of points in the current revolution. Type: `Integer32`
`angle`	Angle of each point, in the unit selected by AngleUnit. Counter-clockwise positive when Inverted is true (default). Type: `Float64`
`distance_in_m`	Distance of each point in meter. Type: `Float64`
`distance_in_mm`	Distance of each point in millimeter. Type: `Integer32`