Rico贾若童的博客

Fitness - Eat, Move, and Burn Smarter

Eat, Move, and Burn Smarter: A Simple Guide to Metabolism Most of us think “eat less, move more” is the whole story of weight loss and health. But under the hood, your body is running a sophistica...

Posted by Rico's Nerd Cluster on May 1, 2025

[3D-SLAM 6] Tightly Coupled Lio

iekf

Introduction If the state estimation process jointly optimizes the states related to multiple sensors rather than treating each module independently, the system is considered tightly coupled. For ...

Posted by Rico's Nerd Cluster on April 20, 2025

Robotics - Moré-Thuente Line Search Algorithm

Introduction Introduced in the early 1990s, line search and trust-region strategies have become standard tools for improving the robustness of iterative optimization methods used in LiDAR odometry...

Posted by Rico's Nerd Cluster on April 17, 2025

Robotics - Gauss Newton (GN) and Levenberg Marquardt (LM) Optimizers

Newton's Method, GN, LM optimizers

Newton’s Method Solving An Equation To find an arbitrary equation’s root $f(x) = 0$, We start from an arbitrary point $x_0$ that’s hopefully close to the solution, $x_s$ The main idea of Ne...

Posted by Rico's Nerd Cluster on April 14, 2025

Robotics - [3D SLAM - 5] LIO Hands-On

Issues That I Encountered Synchronization THere are cases where you lose IMU for a bit. There could be a lag from the liadr to the imu as well. What’s strange is ROS publisher ...

Posted by Rico's Nerd Cluster on April 8, 2025

Robotics - [3D SLAM - 5] Loosely and Tightly Coupled Lidar Inertial Odometry

FastLIO

Loosely vs Tightly Coupled LIO In loosely coupled LIO, the IMU and GPS are first fed into error state kalman filter which outputs a global pose estimate T_G. T_G is fed into a lidar odometer (such...

Posted by Rico's Nerd Cluster on March 11, 2025

Robotics - [3D SLAM - 3] Lidar Odometry

Direct Lidar Odometry, NDT, Incremental NDT, Indirect Lidar Odometry, LOAM

Direct Lidar Odometry When given two scans, a direct NDT method means no features are extracted. The two scans would directly go through NDT for finding their relative poses. The workflow is as fo...

Posted by Rico's Nerd Cluster on March 4, 2025

Robotics - [3D SLAM - 2] Scan Matching Hands-On Notes

Preact-Mojave, Lidar-Only Front-End

Preact-Mojave Build & Workflow The ROS2 driver for Preact-Mojave can be found here. When testing it, I ran into below questions: Why make provision & make ros2? make provisi...

Posted by Rico's Nerd Cluster on March 3, 2025

Robotics - [3D SLAM - 1] Scan Matching

3D Point-Point ICP, 3D Point-Plane ICP, NDT

The Scan Matching Problem When we run scan matching, we usually have two point clouds: a source scan $S_1 = {\mathbf{p}_1, \ldots, \mathbf{p}_n}$ (the new measurement), and a target scan $S_...

Posted by Rico's Nerd Cluster on March 1, 2025

Robotics - [Bugs - 2] SLAM Related Small Bugs

Passing Ptr By Value

⚠️ Beware of Passing Smart Pointers by Value Passing a smart pointer (e.g. std::shared_ptr or boost::shared_ptr) by value is fine when you’re only modifying the object it points to. But if you int...

Posted by Rico's Nerd Cluster on February 1, 2025

Rico's Nerd Cluster