MyRoboPathOpen Robotics Lab
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.

MyRoboPath Engineering Lab
Peer-Reviewed Open-Source Hardware & Firmware Guide

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