14 Dec

#### Nonlinear least squares optimization in SLAM

Previously, I finished the feature matching and id assignment in the SLAM frontend. Last week, I combine the result with the preintegrated IMU data to formulate an optimization problem. Initial values I initialize the landmark position by triangulate two frames. The selection of these two points...

13 Dec

#### Test results of IMU error function

Purpose This blog is to pose optimization results of the IMU erro function in Tsangkai's project. In this test, I try to use simulation data to test the "imu_error" function to examine whether the code is right or not to perform optimization function. Input and output There are two tests. ...

07 Dec

#### SLAM frontend overview

okvis is a visual odometry. Therefore, the feature matching only occurs within short time window, and the feature matching that enables loop closure is not provided. The following is the overview as well as the result of the feature matching that I implemented. Keyframe selection This part relie...

02 Dec

#### Blimp Altitude Filtering Algorithm (Second Order)

This past week, I focused on improving upon the altitude filtering algorithms I had tested previously for the blimps on FORAY. The previous two algorithms I had implemented (both in arduino and in MATLAB) were a moving average filter and an exponential filter (both first-order filters). Both intro...

30 Nov

#### Research plan for Dec. 2020

After surveying several SLAM and visual odometry implementation, I decided to work on okvis with monocular camera setting. I will run an nonlinear optimization on the output of the visual odometry system, which can be regarded as global bundle adjustment with IMU constraints. The output of visua...

24 Nov

#### FORAY - Summary of fist competition

Structure: 4 motors configuration (attackers) 3 motors configuration (defenders) Special case with the strong thrust Electronic system There are several components in our electrical system: Control board: NodeMCU-esp8266 Motor driver: tb6612-fng Motor : 8.5 * 20mm Propeller...

18 Nov

#### Identifying weak points and failure modes in foldable structures, different methods exploration

Method of Weighted Residuals + Galerkin Method "Reduce the continuous-system mathematical model to a discrete idealization." "In applied mathematics, methods of mean weighted residuals (MWR) are methods for solving differential equations. The solutions of these differential equations are assumed...

16 Nov

#### How to deal with obstacles in Trajectory Optimization?

In this tutorial, I show how to deal with obstacles in TO. Let's consider a robot moving in a 2D space. The robot needs to avoid rectangle obstacles. Here, I assume that the shape of the obstacles is represented by its lower left and upper right points, $$\left(x_{\min }, y_{\min }\right)$$ and \...