Rico's Nerd Cluster

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Robotics - General ESKF Hands-on Test Notes

Primers Did you turn on the message debugging flag, or are you compiling with PRINT_DEBUG_MSGS? Are you sure you are launching the right test? IMU tools Velocity drift observed. Here, I’m ...

Posted by Rico's Nerd Cluster on April 3, 2024

Robotics - [IMU Pre-integration Model 4] IMU Pre-integration Optimization Implementation

IMU Pre-Integration, GNSS, UTM

Using Pre-Integration Terms as Edges in Graph Optimization Formulating a graph optimization problem using pre-integration (as edges) and states as nodes is quite flexible. Recall that from here th...

Posted by Rico's Nerd Cluster on April 2, 2024

Robotics - [IMU Pre-integration Model 3] Noise Model

Jacobian Derivation

Pre-integration Model In Graph Optimization using IMU pre-integration, $b_g$ and $b_a$ are factors under optimization. We have derived the Jacobians of pre-integrated intermediate values w.r.t the...

Posted by Rico's Nerd Cluster on April 1, 2024

Robotics - [IMU Pre-integration Model 2] How To Update Pre-integration With Changing IMU Biases

Jacobian Derivation

Update Pre-integration When Updating Biases Pre-integration parts are functions are functions w.r.t gyro and acceleration biases: $b_{g,i}, b_{a,i}$. In graph optimization, we would usually need t...

Posted by Rico's Nerd Cluster on March 29, 2024

Robotics - [IMU Pre-integration Model 1] Definitions Of Pre-Integration Options

Pre-Integration Model Definitions

Motivation In previous posts, we have seen the ESKF framework, where IMU data is fused with observations (GNSS, encoders) following this incremenetal order: 1 ESKF Prediction with IMU | ESKF Pred...

Posted by Rico's Nerd Cluster on March 28, 2024

Robotics - [ESKF Series 5] Why Using Error-State Kalman Filter (ESKF) For IMU

ESKF, GINS

ESKF Handles Rotations on SO(3) Better Key issue: Rotations lie on the special orthogonal group SO(3), which is a nonlinear manifold (not a simple vector space like position). A standard EKF typic...

Posted by Rico's Nerd Cluster on March 24, 2024

Robotics - [ESKF Series 4] Full Error-State Kalman Filter (ESKF) in GNSS-Inertial Navigation System (GINS)

ESKF, GINS

If you haven’t checked out a motivational 2D robot example of ESKF, please check here. In this post, $\oplus$ is the “generic add”, which “adds” on a manifold. ESKF (On Manifold) in GINS (GPS-Int...

Posted by Rico's Nerd Cluster on March 24, 2024

Robotics - [ESKF Series 3] Motivational Example Of Error-State Kalman Filter (ESKF)

ESKF

Motivating Example We use the same example as the one in the EKF post: imagine our world has two cones with known locations: c1, c2, and a diff drive with wheel encoders and a cone detector. T...

Posted by Rico's Nerd Cluster on March 24, 2024

Robotics - [ESKF Series 1] IMU Model

Specific Force, IMU model

Introduction The IMU is a very common localization device. One can find it in most electronics nowadays: cars, smart watches, phones, even soccer balls. Knowing how IMU works could be a long proce...

Posted by Rico's Nerd Cluster on March 22, 2024

Robotics Fundamentals - Extended Kalman Filter (EKF)

Kalman Filter Framework

Welcome To EKF - A Diff Drive Example EKF (Extended Kalman Filter) is widely applied in robotics to smooth sensor noises to get a better estimate of a car’s position. Now let’s take a look at a d...

Posted by Rico's Nerd Cluster on March 15, 2024

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