From Unified Robot Description Format to DH Parameters: Examinations of Two Different Approaches for Manipulator

Abstract

Robot technology is evolving exponentially due to rapid advancements in hardware and software. However, one crucial aspect of robotics has remained unchanged: determining the robot’s position and configuration. To identify a robot’s configuration, we must build a kinematic chain. Traditionally, the Denavit-Hartenberg (DH) parameters have been used to construct kinematic chains in manipulators. DH parameters offer a compact notation and many advantages for kinematic applications. However, they can be challenging for novices unfamiliar with the DH convention. Recently, the Unified Robot Description Format (URDF) has been increasingly adopted for building kinematic chains. URDF is easy to read and intuitive, making it more accessible for constructing kinematic chains. As a result, some engineers prefer URDF, leading to a need for greater mutual understanding between users of DH parameters and URDF. To bridge this gap, we introduce two methods for constructing DH parameters from URDF: the dummy-frame-based approach and the joint-axis-based approach. The dummy-frame-based approach retains the information from URDF, while the joint-axis-based approach focuses on creating an efficient kinematic chain using DH parameters. Both methods produce kinematic chains identical to those from URDF and provide the same forward dynamic results. Consequently, these methods can help robotics engineers quickly adopt and integrate both representations of robot kinematics.

Keywords

• Denavit-Hartenberg (DH) parameters
• unified robot description format (URDF)
• robot kinematics
• robot dynamics
• robot simulation