Kinematic Modelling and Trajectory Planning for a 6-DOF Robotic Arm Using ROS 2 Humble and MoveIt 2: Comparative Evaluation of STOMP, RRT-Connect, and Pilz Industrial Motion Planner

Abstract

The 6-DOF serial robotic arm is the workhorse of industrial automation,capable of reaching any position and orientation within its workspace through the six degrees of freedom provided by its joint chain, and increasingly deployed in research, small-batch manufacturing, and collaborative robot (cobot) contexts where programming flexibility and safety-rated motion are required alongside the traditional speed and repeatability of industrial manipulators. ROS 2 (Robot Operating System 2) and its motion planning framework MoveIt 2 provide the dominant open-source software ecosystem for 6-DOF arm trajectory planning and execution, supporting multiple planning algorithms through a standardised planning interface that enables algorithm comparison within a unified software framework. This study presents the forward and inverse kinematic modelling of a custom-designed 6-DOF robotic arm (workspace radius 0.8 m, payload 2 kg) using Denavit-Hartenberg (DH) parameters, its integration with ROS 2 Humble (Ubuntu 22.04) and MoveIt 2 through an URDF model and custom MoveIt 2 configuration, and a comparative evaluation of three MoveIt 2 trajectory planners — STOMP (Stochastic Trajectory Optimisation for Motion Planning), RRT-Connect (OMPL), and Pilz Industrial Motion Planner — across 200 pick-and-place trial trajectories. STOMP produced the smoothest trajectories (lowest jerk index 0.84 m/s³) at the cost of the longest planning time (842 ms), suitable for precision manipulation tasks tolerating planning latency. Pilz achieved the fastest planning (124 ms) for Cartesian linear (LIN) motion segments essential for structured pick-and-place with defined approach directions, at the cost of higher positioning error (2.24 mm). RRT-Connect provided a balanced intermediate performance (284 ms, 1.48 mm error) suitable for general-purpose collision-aware joint-space motion planning. KEYWORDS: ROS 2, MoveIt 2, 6-DOF robotic arm, Trajectory planning,STOMP, RRT-Connect, Pilz motion planner, Inverse kinematics, Denavit-Hartenberg, Haryana, Industrial robot, Motion planning.