MyRoboPath
kinematics13 min readUpdated 2026-03-06Intermediate

Trajectory Generation: Cubic & Quintic Polynomial Splines

Generate smooth, jerk-continuous robot motion profiles with boundary position, velocity, and acceleration constraints using 5th-order quintic polynomials.

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

Key Engineering Takeaways

  • A path is purely geometric (sequence of poses); a trajectory adds time parameterization (velocities, accelerations, jerks).
  • Cubic polynomials (3rd order) only guarantee continuous velocity; quintic polynomials (5th order) ensure continuous acceleration and bounded jerk.
  • Zero initial and final accelerations prevent mechanical backlash shock on gearboxes.
Prerequisites
  • Polynomial calculus
  • Linear systems of equations

Deriving the 5th-Order Quintic Polynomial System

A quintic trajectory has the form: $$s(t) = a_0 + a_1 t + a_2 t^2 + a_3 t^3 + a_4 t^4 + a_5 t^5$$ With 6 boundary conditions (initial/final position, velocity, and acceleration), solving a $6 \times 6$ linear system yields the coefficients.
Tags:#Trajectory Generation#Quintic Splines#Jerk Reduction#Motion Planning#Interpolation