Safe pHRI via the Variable Stiffness Safety-Oriented Mechanism (V2SOM): Simulation and Experimental Validations

• Published in: Applied sciences Vol. 10; no. 11; p. 3810
• Main Authors: Ayoubi, Younsse, Laribi, Med Amine, Arsicault, Marc, Zeghloul, Said
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.06.2020; Multidisciplinary digital publishing institute (MDPI)
• Subjects: Acoustics; Analysis; Automatic; Biomechanics; Chemical Sciences; Collaboration; Computer simulation; Criteria; Damage assessment; Decoupling; Design and construction; Electric power; Electromagnetism; Energy; Engineering Sciences; Fluid mechanics; friendly cobots; Head injuries; Human subjects; Human-computer interaction; human–robot collisions; Impact loads; Internet of Things; Load; Material chemistry; Materials and structures in mechanics; Mathematical Physics; Mechanics; pHRI; Physics; Polymers; Prevention; Quantum Physics; Reactive fluid environment; Robotics; Robots; Safety; Safety and security measures; safety criteria; Simulation; Stiffness; Thermics; V2SOM; variable stiffness actuator; Vibrations; Working conditions; France; PHRI; Safety criteria; Variable stiffness actuator; V2SOM; Human-robot collisions; Friendly cobots
• ISSN: 2076-3417; 2076-3417
• DOI: 10.3390/app10113810

Robots are gaining a foothold day-by-day in different areas of people’s lives. Collaborative robots (cobots) need to display human-like dynamic performance. Thus, the question of safety during physical human–robot interaction (pHRI) arises. Herein, we propose making serial cobots intrinsically compliant to guarantee safe pHRI via our novel designed device, V2SOM (variable stiffness safety-oriented mechanism). Integrating this new device at each rotary joint of the serial cobot ensures a safe pHRI and reduces the drawbacks of making robots compliant. Thanks to its two continuously linked functional modes—high and low stiffness—V2SOM presents a high inertia decoupling capacity, which is a necessary condition for safe pHRI. The high stiffness mode eases the control without disturbing the safety aspect. Once a human–robot (HR) collision occurs, a spontaneous and smooth shift to low stiffness mode is passively triggered to safely absorb the impact. To highlight V2SOM’s effect in safety terms, we consider two complementary safety criteria: impact force (ImpF) criterion and head injury criterion (HIC) for external and internal damage evaluation of blunt shocks, respectively. A pre-established HR collision model is built in Matlab/Simulink (v2018, MathWorks, France) in order to evaluate the latter criterion. This paper presents the first V2SOM prototype, with quasi-static and dynamic experimental evaluations.