Hi there, thank you very much for your great work!
I am using the mid-360 lidar with point-lio. I would like to clarify some questions I have about the configuration parameters when I would like to tilt the lidar instead of using it flat mounted. When I am using it flat mounted, I am using the following config params (note: this is in simulation, so the imu sits in the same frame as the lidar source):
common:
lid_topic: "/livox/lidar"
imu_topic: "/livox/imu"
# imu_topic: "/uav1/hw_api/imu"
con_frame: false # true: if you need to combine several LiDAR frames into one
con_frame_num: 1 # the number of frames combined
cut_frame: false # true: if you need to cut one LiDAR frame into several subframes
cut_frame_time_interval: 0.1 # should be integral fraction of 1 / LiDAR frequency
time_lag_imu_to_lidar: 0.0 # Time offset between LiDAR and IMU calibrated by other algorithms, e.g., LI-Init (find in Readme)
# the timesample of IMU is transferred from the current timeline to LiDAR's timeline by subtracting this value
preprocess:
lidar_type: 1
scan_line: 6
timestamp_unit: 1 # the unit of time/t field in the PointCloud2 rostopic: 0-second, 1-milisecond, 2-microsecond, 3-nanosecond.
blind: 1.0 # also from https://github.com/hku-mars/Point-LIO/issues/24, sometimes 0.5?
mapping:
imu_en: true
extrinsic_est_en: false # for aggressive motion, set this variable false
imu_time_inte: 0.01 # = 1 / frequency of IMU
satu_acc: 4.0 # the saturation value of IMU's acceleration. not related to the units # TODO: should be 4.0 not 30.0?
satu_gyro: 35 # the saturation value of IMU's angular velocity. not related to the units
acc_norm: 9.81 # 1.0 for g as unit, 9.81 for m/s^2 as unit of the IMU's acceleration
lidar_meas_cov: 0.1 # 0.001; 0.01
acc_cov_output: 500
gyr_cov_output: 1000
b_acc_cov: 0.0001
b_gyr_cov: 0.0001
imu_meas_acc_cov: 0.01 #0.1 # 0.1
imu_meas_omg_cov: 0.1 #0.01 # 0.1
gyr_cov_input: 0.01 # for IMU as input model
acc_cov_input: 0.1 # for IMU as input model
plane_thr: 0.05 # 0.05, the threshold for plane criteria, the smaller, the flatter a plane
match_s: 81
fov_degree: 360
det_range: 50.0
gravity_align: false # true to align the z axis of world frame with the direction of gravity, and the gravity direction should be specified below
gravity: [0.0, 0.0, -9.810] # [0.0, 9.810, 0.0] # gravity to be aligned
gravity_init: [0.0, 0.0, -9.810] # [0.0, 9.810, 0.0] # # preknown gravity in the first IMU body frame, use when imu_en is false or start from a non-stationary state
# TODO: is this true for MID360 Livox?
extrinsic_T: [ 0.0, 0.0, 0.0 ]
extrinsic_R: [ 1, 0, 0,
0, 1, 0,
0, 0, 1 ]
# extrinsic_T: [ 0.074, 0.0, 0.104 ]
odometry:
publish_odometry_without_downsample: false
publish:
path:
enable: true # false: close the path output
# TODO: use these values in code
diff_t: 0.01 # (m) publish when translation has changed by this value
diff_R: 0.01 # (rad) publish when one of the Euler angles has changed by this value
scan_publish_en: true # false: close all the point cloud output TODO: might want to enable this and disable below
scan_bodyframe_pub_en: false # true: output the point cloud scans in IMU-body-frame
pcd_save:
pcd_save_en: false
interval: -1 # how many LiDAR frames saved in each pcd file;
# -1 : all frames will be saved in ONE pcd file, may lead to memory crash when having too much frames.
If I want to pitch the lidar for example 25 degrees down, so that it sees more of the floor, do I need to alter any of the parameters relating to gravity i.e.
gravity_align: false # true to align the z axis of world frame with the direction of gravity, and the gravity direction should be specified below
gravity: [0.0, 0.0, -9.810] # [0.0, 9.810, 0.0] # gravity to be aligned
gravity_init: [0.0, 0.0, -9.810] # [0.0, 9.810, 0.0]
or any other parameters?
Your help would be greatly appreciated, thank you.
Kind regards
Hi there, thank you very much for your great work!
I am using the mid-360 lidar with point-lio. I would like to clarify some questions I have about the configuration parameters when I would like to tilt the lidar instead of using it flat mounted. When I am using it flat mounted, I am using the following config params (note: this is in simulation, so the imu sits in the same frame as the lidar source):
If I want to pitch the lidar for example 25 degrees down, so that it sees more of the floor, do I need to alter any of the parameters relating to gravity i.e.
or any other parameters?
Your help would be greatly appreciated, thank you.
Kind regards