Comparative analysis of inverse kinematics strategies for effective control of redundant manipulators in collaborative robotics

The shift from Industry 4.0 to Industry 5.0 embraces human-centricity, prioritizing technology that enhances rather than replaces human capabilities. This approach improves collaboration between humans and machines, exploiting their complementary skills to achieve a common goal. While a 6-Degrees of Freedom (DoF) robot arm already resembles the human arm, a 7-DoF design more closely mimics its dexterity, providing greater control and optimizing robot motion in terms of joint limits, obstacle avoidance, and energy efficiency. The integration of a linear guide is a practical solution for implementing a seventh DoF, enabling translational movement of the robot base. Research has already explored its benefits in various applications such as humanoid manipulators, industrial robots, and robots for agriculture. However, the redundancy introduced by a linear guide remains unexplored in collaborative robotics, where it could significantly enhance safety and efficiency. Accordingly, the aim of this thesis is to compare inverse kinematics strategies for effectively controlling redundant manipulators in human-robot collaboration scenarios. In the first chapter, the introduction provides an overview of collaborative robots (cobots) and their increasing role in Industry 5.0, emphasizing their challenging integration into human-robot teams. Moreover, the literature gap about the integration of a linear guide for cobots is stressed and the aim of the thesis is defined. In the second chapter, the model of a linear manipulator is presented, along with basic approaches to solve the IK problem for redundant robots. Mathematical formulations and algorithms implementation are presented, specifically focusing on the pseudo-inverse, weighted pseudo-inverse, and Damped Least Squares methods. In the third chapter, two trajectories are analyzed to explore and understand advantages and disadvantages of the proposed approach, which are summarized in the conclusions.