Complete design methodology of biomimetic safety device for cobots’ prismatic joints

• Published in: Robotics and autonomous systems Vol. 102; pp. 44 - 53
• Main Authors: Ayoubi, Y., Laribi, M.A., Courrèges, F., Zeghloul, S., Arsicault, M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2018; Elsevier
• Subjects: Acoustics; Automatic; Biomechanics; Biomimetics; Chemical Sciences; Electric power; Electromagnetism; Engineering Sciences; Fluid mechanics; Material chemistry; Materials and structures in mechanics; Mathematical Physics; Mechanical design; Mechanics; Passive Compliance; Physics; Polymers; Prismatic Compliant Joint; Quantum Physics; Reactive fluid environment; Safety; Thermics; Vibrations; Passive Compliance; Mechanical design; Safety; Biomimetics; Prismatic Compliant Joint; Prismatic; Compliant Joint
• ISSN: 0921-8890; 1872-793X
• DOI: 10.1016/j.robot.2018.01.008

Making robots collaborate safely with humans has created a new design paradigm involving the biomimetic mechanical behavior of robots’ joints. However, few authors have contributed to the problems of safety in pure linear motion, i.e. a prismatic joint, in contrast to rotary motion. The contribution of this work is to present a new design that is capable of achieving, passively, an implementation of nonlinear elastic behavior for prismatic joints—the so-called Prismatic Compliant Joint (PCJ). This new device is based on the association of a six-bar mechanism with a linear spring. Hence, this structure generates a nonlinear stiffness behavior under a specified external force. The elastic characteristics of the PCJ are derived from a generic biological muscle mechanical behavior model and then customized according to the force-safety criteria of physical Human/Robot Interaction (pHRI) into a Hunt–Crossley contact model. A further investigation is carried out, via simulation, to verify the shock absorption capacity of the PCJ with a dummy head obstacle. In order to fit the PCJ response curve to the established safety measures, an optimization based on a genetic algorithm method is employed to tune the PCJ’s intrinsic parameters subject to some chosen constraints. •Prismatic Compliant Joint (PCJ).•Safe physical human/robot interaction.•Biomimetic mechanical behavior of robots’ joints.•Force-safety criteria of physical Human/Robot Interaction.•Optimization based on a genetic algorithm method.