Admittance Control of the UR3e Robot Manipulator

Samuel Teixeira Vaz

Key information

Authors:

Samuel Teixeira Vaz (Samuel Teixeira Vaz)

Supervisors:

João Paulo Mendes Oliveira (João Paulo Mendes Oliveira); Jorge Manuel Mateus Martins (Jorge Manuel Mateus Martins)

Published in

April 30, 2025

Abstract

This thesis investigates the implementation of admittance control on a UR3e collaborative robot (cobot) for improved physical human-robot interaction (pHRI). Admittance control is employed to establish a compliant dynamic response between the robot and external forces, allowing the robot to adjust its motion based on environmental interactions. This approach is particularly beneficial for collaborative settings, where safety and adaptability are essential. The study involves the development of an admittance control, in the UR3e, to be further included in a system together with a linear guide and a base force/torque sensor. Key aspects include a proposed inverse kinematics solution for the kinematic redundant system along with its dynamic model. Furthermore, a thorough analysis of the communication protocol and of the robot’s low-level control functions, along with the implementation of a low-pass filter. Experimental trials validate the admittance controllers performance, leading to the definition and validation of suitable parameter working intervals under both static and dynamic conditions, thereby confirming the controllers effectiveness in achieving safe human-cobot collaboration. Additionally, an implementation of a pick-and-place trajectory was performed, guaranteeing the safe usage of the controller.