May 16, 2024

Measured the connector of the Velodyne. Outside is 5.5 mm, inside is 1.8 mm. Nearly the specs of 12V Powerbank.

May 14, 2024

Looking into a battery for the Velodyne VPL-16. According to specifications, the power can be between 9 and 18V DC / 5W. That is less than 1 A. The connector seems to be DC3 or DC5.
Found this 12V Powerbank, which has a (5,5x2,1 centrumpositief) connector. It can deliver 1.5A. It can be charged via the micro-USB or USB-C port. The USB-ports can also be used as output.

May 6, 2024

At page 61, in note 26, in the Tutorial from Joan Solà, the following advice is given: "We give the simplest form of the covariance update, P ← (I−KH)P. This form is known to have poor numerical stability, as its outcome is not guaranteed to be symmetric nor positive definite. The reader is free to use more stable forms such as 1) the symmetric form P ← P − K(HPH > + V)K > and 2) the symmetric and positive Joseph form P ← (I − KH)P(I − KH) > + KVK"
There is no urdf in the unilidar_sdk github.
The transform is specified in the point-lio unilidar github. Note that there is also a configuration for the velodyne 16.
On June 19, 2023 I connected the Velodyne Puck to my Windows-partition of nb-dual. I also did it later with the Linux-partition, actually in the atwork labbook. Somewhere after April 22, 2024; when I received the instructions of Joey. The ~/catkin_ws/src/velodyne is from April 23 - which corresponds with the labbook entry.
Found the GPS sensor in the AI Kit box.
Found way to connect the Velodyne Puck VLP-16 back:
With the cover on it, the connection should be as follows:
For ROS noetic, I could follow Getting Started
Tried roslaunch velodyne_pointcloud VLP16_points.launch. I see logmessage "Opening UDP socket: port 2368", have not checked the ip yet.
Following the instruction and setting up a route to Velodyne ip worked. Did not get any view in RVIZ, because the velodyne frame was not known.
Tried roslaunch velodyne_pointcloud transform_nodelet.launch, but that failed because it needed the service advertised by velodyne_nodelet_manager.
Could have started velodyne_nodelet_manager velodyne_driver nodelet_manager.launch, but gave the Velodyne to Basille.
Looked into the code of the transform, but it looks like applying the calibration data to compensate for the RPM. Also handy, but I could also have used rosrun tf static_transform_publisher 0 0 0 0 0 0 map velodyne 100
Should look for a robot_description to get a better defined transform (xyz="0 0 0.0377").

May 5, 2024

Continued with launch of the RVIZ viewer of the point-cloud of the Unitree L1 Lidar.
The command roslaunch unitree_lidar_ros run.launch gives an error:
process[unitree_lidar_ros_node-3]: started with pid [30031] terminate called after throwing an instance of 'serial::IOException' what(): IO Exception (13): Permission denied, file /home/mlb/ut_workspace/202207_unitree_selfmade_lidar/unitree_lidar_sdk/unitree_lidar_sdk/src/serial/impl/unix.cc, line 151
Strange, because the default /dev/ttyUSB0 is of group dailout (rw), so am I.
After sudo chmod o+rw /dev/ttyUSB0 the sensor can be read out. Only missing is the transform to frame unilidar_lidar.
Running rosrun tf static_transform_publisher 0 0 0 0 0 0 map unilidar_lidar 100 solves this partly. The lidar frame is now known, the unilidar_imu is still unknown.
That could be solved with rosrun tf static_transform_publisher 0 0 10 0 0 0 unilidar_lidar unilidar_imu 100:
Should look up the correct transforms in the documentation, or see if there is description. I have saw a 3D model in the downloads.

May 4, 2024

Found the github for the Unitree L1 Lidar.
The Start Guide and SDK can be found download page.
As official software they indicate a Windows-based viewer.
Yet, there are also instructions for ROS Noetic.
Started with the dependencies mention in Point LIO SLAM github. Both pcl-conversions and libeigen3-dev were already installed.

May 3, 2024

This Tutorial from IRI, Barcelona explains the use of EKF with quaternions.
According to this blog, the Orbbec Gemini 2L is more stable than the RealSense D455.

March 11, 2024

A list of Robotics and Automation IEEE Keywords can be found here

February 16, 2024

Should watch OpenCV live on the mini Pupper 2 when I have time.
Although the youTube release is from Feb 2024, the recording is actually from 9 Dec 2022.