MyRoboPath
kinematics16 min readUpdated 2026-03-08Advanced

Quaternions & 3D Spatial Rotations in Robotics

Escape Euler angle gimbal lock: master unit quaternions, SO(3) Lie groups, spherical linear interpolation (SLERP), and rotation matrix conversions for robot poses.

Dr. Soraya Al-Mansoor
Dr. Soraya Al-Mansoor
Professor of Robotics & Nonlinear Control

Key Engineering Takeaways

  • Euler angles suffer from Gimbal Lock (loss of 1 degree of freedom when pitch reaches ±90°); Quaternions provide singularity-free representation.
  • A unit quaternion consists of 4 numbers: q = [w, x, y, z] with ||q|| = 1.
  • SLERP smoothly interpolates between two 3D orientations at constant angular velocity.
Prerequisites
  • Complex numbers
  • Vector cross products

Why Quaternions? The Flaws of Euler Angles

In 3D robotics simulation and drone flight control, representing orientation with Roll-Pitch-Yaw (Euler angles) causes catastrophic mathematical singularities whenever the middle gimbal aligns with the outer gimbal, destroying the ability to distinguish pitch from yaw.
Tags:#Quaternions#Rotations#Gimbal Lock#SLERP#SO3#Spatial Math