Original scientific paper

https://doi.org/10.21860/medflum2022_284696

Hand model with dependency constrained joints for applications in rehabilitation robotics

Tomislav Bazina ; University of Rijeka, Faculty of Engineering, Rijeka, Croatia
Ervin Kamenar ; University of Rijeka, Faculty of Engineering, Rijeka, Croatia
Saša Zelenika ; University of Rijeka, Faculty of Engineering, Rijeka, Croatia
Nelida Črnjarić-Žic ; University of Rijeka, Faculty of Engineering, Rijeka, Croatia
Tea Schnurrer-Luke-Vrbanić ; University of Rijeka, Faculty of Medicine, Department for Physical and Rehabilitation Medicine, Rijeka, Croatia

Abstract

Aim: This work presents a method for developing a simplified but efficient model of the complex human hand kinematics with the aim of its implementation in rehabilitation robotics. Material and methods: The approach incorporates modularity by simplifying the available model comprising 24 degrees of freedom (DOFs) to 9 DOFs, with the introduction of additional joint coupling parameters specific to different grasp types. The effect of dependent joints to the ranges-of-motion (ROMs) of the model is investigated and compared to the anatomical one. The index, middle, ring and little finger solutions to forward and inverse kinematics problems are then acquired. The implementation of the model, based on the median male bones dimensions, is made available in the open-source Robot Operating System (ROS) framework. Results: By including additional four inclination angles per finger, the devised kinematic hand model encompasses also finger curvatures, resulting in significant positioning accuracy improvements compared to the conventional model. The used 3D spatial position improvement metrics are the mean absolute (MAE) and mean relative errors (MRE). The dependent joint position MAEs range from 0.22 to 0.34 cm, while MREs range from 2.8 and 3.5 %, whereas the highest absolute and relative errors during fingertip positioning can reach 0.5 cm and 10.5 %, respectively. Conclusion: The performed investigation allowed establishing that by modelling finger curvature and assuring the adaptability of the model to a variety of human hands and rehabilitation modalities through joint dependency, represents the best approach towards a relatively simple and applicable rehabilitation model with functional human-like hand movements.

Keywords

hand bones; hand joints; range of motion, articular; rehabilitation; robotics; software

Hrčak ID:

284696

URI

https://hrcak.srce.hr/284696

Publication date:

1.12.2022.

Article data in other languages: croatian

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