[fix] The unit of linear_acceleration is m/s^2

[h-wata]

Summary

The unit of linear_acceleration in the imu is G, but it should be m/s^2 according to the wiki.

Accelerations should be in m/s^2 (not in g's), and rotational velocity should be in rad/sec

Detail

• Change files

  • modified: livox_ros_driver/lddc.cpp
  • modified: livox_ros_driver/lddc.h

• Refs #63

• Effect Comparison of rostopic echo /livox/imu_XXXXX in bag file converted by lvx_to_rosbag.launch from same lvx file.

Before

---
header:
  seq: 0
  stamp:
    secs: 1628129261
    nsecs: 482877970
  frame_id: "livox_frame"
orientation:
  x: 0.0
  y: 0.0
  z: 0.0
  w: 0.0
orientation_covariance: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
angular_velocity:
  x: -0.021623685956
  y: -0.0181506872177
  z: -0.0124202724546
angular_velocity_covariance: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
linear_acceleration:
  x: 0.0482514984906
  y: -0.00931103434414
  z: 0.876538217068
linear_acceleration_covariance: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
---

After

---
header:
  seq: 0
  stamp:
    secs: 1628129299
    nsecs: 774994612
  frame_id: "livox_frame"
orientation:
  x: 0.0
  y: 0.0
  z: 0.0
  w: 0.0
orientation_covariance: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
angular_velocity:
  x: 0.0199216287583
  y: -0.0415865033865
  z: 0.547908842564
angular_velocity_covariance: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
linear_acceleration:
  x: 0.0861642286181
  y: 0.872362732887
  z: 9.27106189728
linear_acceleration_covariance: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
---