Importing the Human Factor into Safe Human–Robot Interaction Function Using the Bond Graph Method

Robotica ◽  
2020 ◽  
pp. 1-15
Author(s):  
Po-Jen Cheng ◽  
Hsiang-Yuan Ting ◽  
Han-Pang Huang
Keyword(s):  
Joint Stiffness ◽  
Variable Stiffness ◽  
Human Robot Interaction ◽  
Fault Detection And Isolation ◽  
Robot Interaction ◽  
Protection Measures ◽  
Robust Fault Detection ◽  
Collision Safety ◽  
Additional Protection ◽  
Fault Mode

SUMMARY The variable stiffness actuator (VSA) is helpful to realize the post-collision safety strategies for safe human–robot interaction.1 The stiffness of the robot will be reduced to protect the user from injury when the collision between the robot and human occurs. However, The VSA has a mechanism limit constraint that can cause harm to users even if the stiffness is minimized. Accordingly, in this article, a concept combining danger index and robust fault detection and isolation is presented and applied to active–passive variable stiffness elastic actuator (APVSEA). APVSEA can actively change joint stiffness with the change of danger index. Experimental results show that this concept can effectively confirm the fault mode and provide additional protection measures to ensure the safety of users when the joint stiffness has been adjusted to the minimum.

scholarly journals A Stiffness Variable Passive Compliance Device with Reconfigurable Elastic Inner Skeleton and Origami Shell

2020 ◽  
Vol 33 (1) ◽  
Author(s):  
Zhuang Zhang ◽  
Genliang Chen ◽  
Weicheng Fan ◽  
Wei Yan ◽  
Lingyu Kong ◽  
...  
Keyword(s):  
Variable Stiffness ◽  
Rehabilitation Robotics ◽  
Human Robot Interaction ◽  
Main Concept ◽  
Robot Interaction ◽  
Switching Speed ◽  
Leaf Springs ◽  
Stiffness Variation ◽  
Low Stiffness ◽  
Large Deflection Problem

Abstract Devices with variable stiffness are drawing more and more attention with the growing interests of human-robot interaction, wearable robotics, rehabilitation robotics, etc. In this paper, the authors report on the design, analysis and experiments of a stiffness variable passive compliant device whose structure is a combination of a reconfigurable elastic inner skeleton and an origami shell. The main concept of the reconfigurable skeleton is to have two elastic trapezoid four-bar linkages arranged in orthogonal. The stiffness variation generates from the passive deflection of the elastic limbs and is realized by actively switching the arrangement of the leaf springs and the passive joints in a fast, simple and straightforward manner. The kinetostatics and the compliance of the device are analyzed based on an efficient approach to the large deflection problem of the elastic links. A prototype is fabricated to conduct experiments for the assessment of the proposed concept. The results show that the prototype possesses relatively low stiffness under the compliant status and high stiffness under the stiff status with a status switching speed around 80 ms.

scholarly journals Soft Robotics with Variable Stiffness Actuators: Tough Robots for Soft Human Robot Interaction

Soft Robotics ◽  
2015 ◽  
pp. 231-254 ◽  
Author(s):  
Sebastian Wolf ◽  
Thomas Bahls ◽  
Maxime Chalon ◽  
Werner Friedl ◽  
Markus Grebenstein ◽  
...  
Keyword(s):  
Variable Stiffness ◽  
Human Robot Interaction ◽  
Soft Robotics ◽  
Robot Interaction ◽  
Variable Stiffness Actuators

Determination of Variable Stiffness of a Human Elbow for Human-Robot Interaction

2014 ◽  
Author(s):  
Michael Boyarsky ◽  
Megan Heenan ◽  
Scott Beardsley ◽  
Philip Voglewede
Keyword(s):  
Experimental Data ◽  
Disturbance Rejection ◽  
Variable Stiffness ◽  
Important Variable ◽  
Human Motion ◽  
Human Robot Interaction ◽  
Robot Interaction ◽  
Constant Stiffness ◽  
Stiffness Model ◽  
Motor Model

This paper aims to emulate human motion with a robot for the purpose of improving human-robot interaction (HRI). In order to engineer a robot that demonstrates functionally similar motion to humans, aspects of human motion such as variable stiffness must be captured. This paper successfully determined the variable stiffness humans use in the context of a 1 DOF disturbance rejection task by optimizing a time-varying stiffness parameter to experimental data in the context of a neuro-motor Simulink model. The significant improved agreement between the model and the experimental data in the disturbance rejection task after the addition of variable stiffness demonstrates how important variable stiffness is to creating a model of human motion. To enable a robot to emulate this motion, a predictive stiffness model was developed that attempts to reproduce the stiffness that a human would use in a given situation. The predictive stiffness model successfully decreases the error between the neuro-motor model and the experimental data when compared to the neuro-motor model with a constant stiffness value.

Design of a Variable Stiffness Actuator Based on Flexures

2011 ◽  
Vol 3 (3) ◽  
Author(s):  
Gianluca Palli ◽  
Giovanni Berselli ◽  
Claudio Melchiorri ◽  
Gabriele Vassura
Keyword(s):  
Compliant Mechanism ◽  
Variable Stiffness ◽  
Human Robot Interaction ◽  
Experimental Characterization ◽  
Robot Interaction ◽  
Trade Off ◽  
Variable Stiffness Actuator ◽  
Robotic Devices ◽  
Stiffness Profile ◽  
Variable Stiffness Actuators

Variable stiffness actuators can be used in order to achieve a suitable trade-off between performance and safety in robotic devices for physical human–robot interaction. With the aim of improving the compactness and the flexibility of existing mechanical solutions, a variable stiffness actuator based on the use of flexures is investigated. The proposed concept allows the implementation of a desired stiffness profile and range. In particular, this paper reports a procedure for the synthesis of a fully compliant mechanism used as a nonlinear transmission element, together with its experimental characterization. Finally, a preliminary prototype of the overall joint is depicted.

A Comparative Study on the Effect of Mechanical Compliance for a Safe Physical Human–Robot Interaction

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Yu She ◽  
Siyang Song ◽  
Hai-Jun Su ◽  
Junmin Wang
Keyword(s):  
Impact Force ◽  
Variable Stiffness ◽  
Human Robot Interaction ◽  
Design Parameters ◽  
Robot Dynamics ◽  
Robot Interaction ◽  
Promising Alternative ◽  
Mechanical Compliance ◽  
Maximum Impact Force ◽  
The Impact

Abstract In this paper, we study the effects of mechanical compliance on safety in physical human–robot interaction (pHRI). More specifically, we compare the effect of joint compliance and link compliance on the impact force assuming a contact occurred between a robot and a human head. We first establish pHRI system models that are composed of robot dynamics, an impact contact model, and head dynamics. These models are validated by Simscape simulation. By comparing impact results with a robotic arm made of a compliant link (CL) and compliant joint (CJ), we conclude that the CL design produces a smaller maximum impact force given the same lateral stiffness as well as other physical and geometric parameters. Furthermore, we compare the variable stiffness joint (VSJ) with the variable stiffness link (VSL) for various actuation parameters and design parameters. While decreasing stiffness of CJs cannot effectively reduce the maximum impact force, CL design is more effective in reducing impact force by varying the link stiffness. We conclude that the CL design potentially outperforms the CJ design in addressing safety in pHRI and can be used as a promising alternative solution to address the safety constraints in pHRI.

scholarly journals V2SOM: A Novel Safety Mechanism Dedicated to a Cobot’s Rotary Joints

Robotics ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 18 ◽  
Author(s):  
Younsse Ayoubi ◽  
Med Laribi ◽  
Said Zeghloul ◽  
Marc Arsicault
Keyword(s):  
Good Control ◽  
Variable Stiffness ◽  
Human Robot Interaction ◽  
Industrial Robots ◽  
Necessary Condition ◽  
Physical Interaction ◽  
Robot Interaction ◽  
Internal Damage ◽  
Low Stiffness ◽  
The Impact

Unlike “classical” industrial robots, collaborative robots, known as cobots, implement a compliant behavior. Cobots ensure a safe force control in a physical interaction scenario within unknown environments. In this paper, we propose to make serial robots intrinsically compliant to guarantee safe physical human–robot interaction (pHRI), via our novel designed device called V2SOM, which stands for Variable Stiffness Safety-Oriented Mechanism. As its name indicates, V2SOM aims at making physical human–robot interaction safe, thanks to its two basic functioning modes—high stiffness mode and low stiffness mode. The first mode is employed for normal operational routines. In contrast, the low stiffness mode is suitable for the safe absorption of any potential blunt shock with a human. The transition between the two modes is continuous to maintain a good control of the V2SOM-based cobot in the case of a fast collision. V2SOM presents a high inertia decoupling capacity which is a necessary condition for safe pHRI without compromising the robot’s dynamic performances. Two safety criteria of pHRI were considered for performance evaluations, namely, the impact force (ImpF) criterion and the head injury criterion (HIC) for, respectively, the external and internal damage evaluation during blunt shocks.

scholarly journals Mechanical design and analysis of a novel variable stiffness actuator with symmetrical pivot adjustment

2021 ◽  
Author(s):  
Yiwei Liu ◽  
Shipeng Cui ◽  
Yongjun Sun
Keyword(s):  
Modular Design ◽  
Mechanical Design ◽  
Bending Moment ◽  
Variable Stiffness ◽  
Fast Response ◽  
Human Robot Interaction ◽  
Asymmetric Structure ◽  
Robot Interaction ◽  
Collaborative Robotics ◽  
Variable Stiffness Actuator

AbstractThe safety of human-robot interaction is an essential requirement for designing collaborative robotics. Thus, this paper aims to design a novel variable stiffness actuator (VSA) that can provide safer physical human-robot interaction for collaborative robotics. VSA follows the idea of modular design, mainly including a variable stiffness module and a drive module. The variable stiffness module transmits the motion from the drive module in a roundabout manner, making the modularization of VSA possible. As the key component of the variable stiffness module, a stiffness adjustment mechanism with a symmetrical structure is applied to change the positions of a pair of pivots in two levers linearly and simultaneously, which can eliminate the additional bending moment caused by the asymmetric structure. The design of the double-deck grooves in the lever allows the pivot to move freely in the groove, avoiding the geometric constraint between the parts. Consequently, the VSA stiffness can change from zero to infinity as the pivot moves from one end of the groove to the other. To facilitate building a manipulator in the future, an expandable electrical system with a distributed structure is also proposed. Stiffness calibration and control experiments are performed to evaluate the physical performance of the designed VSA. Experiment results show that the VSA stiffness is close to the theoretical design stiffness. Furthermore, the VSA with a proportional-derivative feedback plus feedforward controller exhibits a fast response for stiffness regulation and a good performance for position tracking.

scholarly journals Design and Analysis of Variable Flexible Actuator for Human-Robot Interaction

2019 ◽  
Vol 37 (2) ◽  
pp. 242-248
Author(s):  
Wendong Wang ◽  
Tongsen Sun ◽  
Xiaoqing Yuan ◽  
Jinzhe Li ◽  
Xing Ming
Keyword(s):  
Magnetic Field ◽  
Variable Stiffness ◽  
Mechanical Analysis ◽  
Simulation Software ◽  
Human Robot Interaction ◽  
Field Analysis ◽  
Robot Interaction ◽  
Magnetic Field Analysis ◽  
Mr Effect ◽  
The Magnetic Field

In view of the shortcomings of the traditional high-rigidity robots that can't ensure safety of human-robot interaction and the adaptability of complex environment, a variable stiffness flexible actuator is proposed for the robot joint based on the magnetorheological (MR) effect of MR Fluids. In this paper, the principle of flexible joint drive is detailed, and design the structure of the drive and perform mechanical analysis is designed. At the same time, the magnetic field analysis of the actuator is carried out by using the magnetic field simulation software Maxwell. Finally, the actuator is simulated and verified. Comparing the analysis of the results, the actuator has the characteristics of simple structure, easy control and wider active variable stiffness adjustment range, and can absorb the vibration or shock energy, and improve the robot joint output ability.

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