Population vs Sample Standard Deviation
The difference between population standard deviation and sample standard deviation boils down to who you’re measuring and how you correct for bias...
Hi, I'm Kanishke
Sensor Fusion & Navigation Engineer
Personal website and blog about UAVs, robotics, control systems, navigation, and embedded software engineering.
All Posts
Finding Your Place in an Infinite Sea
Navigation at sea was one of history’s greatest intellectual and engineering challenges. For sailors who ventured beyond sight of shore, the ocean...
The Schuler Period: Resonance at the Heart of Inertial Navigation
An inertial navigation system that is perfectly tuned to Earth's geometry will oscillate with a period of 84.4 minutes — a consequence...
Quick Reference: Converting Latitude/Longitude Differences to Meters
A practical reference for converting small angular differences in latitude or longitude into metric distances, with interactive tools and the Haversine formula...
Rotation Matrix Construction
A concise guide to constructing a rotation matrix in SO(3) for coordinate frame transformations, with an interactive visualizer.
Job Search Data - 2023 June
“Shopping” for a job is not always a fun process. After a large layoff at my previous employment (a start-up company) in...
Simulink Matrix Concatenation: A Quick Reference
A concise reference for horizontal and vertical matrix concatenation in Simulink — covering block behaviour, dimension rules, and worked examples.
Adding an Interactive Plotly Plot to a Markdown Page
If you are using Python for visualizing data, plotly is an awesome open-source library (also, plotly is not limited to Python). This...
Numerical Instabilities in Kalman Filters: Causes, Consequences, and Mitigations
The Kalman filter, despite its optimality guarantees under Gaussian assumptions, is susceptible to numerical degradation in practice. This post examines the root...
A Linear PID Controlled UAV with ROS + Gazebo
The repository fdcl-uav/gazebo_uav_control is a basic example for using ROS and Gazebo to position control a quadrotor UAV, using C++. A simple...
Vision-Based Autonomous Landing of a UAV on a Moving Ship
This is an extension of the Autonomous Landing of a UAV on a Moving Ship project. Here, a GPS-denied environment is assumed...
Git Cheatsheet
This is a quick cheatsheet for git aliases that I use often.
Adding a Snapshot View to the GitHub Profile
You can a quick snapshot view to your GitHub profile page like the image above. The process is as simple as creating...
A Guided Tour of the PX4 Codebase
PX4 is one of the most widely used open-source autopilot stacks in both academia and industry. This post walks through its layered...
Jerk-Limited Trajectory
This post tries to explain the basics of a trajectory that tries to limit the acceleration or the jerk. If you are...
Plotting a 3D UAV with Matplotlib
If you are visualizing anything with Python, Matplotlib is probably going to be an essential tool. While the library provides really great...
Autonomous Landing of a UAV on a Moving Ship
For an autonomous UAV, or for any aerial vehicle in general, one of the most safety critical operations is the landing. This...
C++ Copy Ellision
Copy elision in C++ is a powerful optimization technique where the compiler eliminates unnecessary copying or moving of objects. It’s like the...
Centrifugal vs Centripetal Forces
These two forces often get tangled up in physics discussions, especially when dealing with circular motion. Let’s break them down clearly:
SO(3) and Attitude Representation
A technical treatment of the Special Orthogonal Group SO(3): its algebraic structure, topological properties, and practical role in rigid-body attitude representation, with...
OpenCV rvec-tvec Definitions
The OpenCV library uses rvec and tvec to represent the rotations and translations, respectively. When you are learning OpenCV, this could be...
Error-State Extended Kalman Filter for GNSS/INS Navigation
A detailed walkthrough of the error-state EKF with SO(3) attitude, ECEF-frame INS propagation, and GPS PVT corrections — including an interactive visualization...
A Taxonomy of Kalman Filters
A comparative treatment of the standard, extended, unscented, and particle filter families — covering their theoretical foundations, computational properties, and practical trade-offs....
Decoupled-Yaw Geometric Control for Unmanned Aerial Vehicles
A UAV is an inherently unstable system, which is similar to an inverted pendulum. The system has a single directional control input...
Covariance Transformation Between Coordinate Frames
A concise reference for transforming a covariance matrix from one coordinate frame to another via a rotation matrix, with derivation and worked...
Loop Nest Optimization
Loop nest optimization is a powerful technique used in compiler design and performance engineering to improve the efficiency of programs—especially those involving...
Smart Pointers in C++
Smart pointers in C++ are powerful tools that help manage memory automatically, reducing the risk of memory leaks and dangling pointers. Instead...
Measurements of Ship Air Wake Using Airborne Anemometers
When a ship moves on a water surface, we can clearly see a water wake right behind it. Its size and the...
Low-Pass Filters
A first-order low-pass filter passes low-frequency signals while attenuating high-frequency noise. This post derives the discrete-time update equation, explains the role of...
Averaging Filters
An introduction to simple averaging and moving average filters — two foundational techniques for reducing measurement noise — with an interactive comparison....
Locally Backup GitHub Repositories
If you need to download your GitHub repositories, one option you have is to open each of them on GitHub and manually...
Generating Hybrid Images
A hybrid image is an image that is perceived in one of two different ways, depending on viewing distance. A technique for...
Implementing an Intrinsic Nonlinear PID Controller
For the final year undergrad group project at the Mechanical Engineering Department at the University of Peradeniya, I was involved in an...
Mathematical Modelling Simulation and Control of a SpiderCam System
As a third year undergrad student of the Mechanical Engineering Department at the University of Peradeniya, we are required to an individual...