scholarly journals Cobot with Prismatic Compliant Joint Intended for Doppler Sonography

Robotics ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 14 ◽  
Author(s):  
Juan Sandoval ◽  
Med Amine Laribi ◽  
Saïd Zeghloul ◽  
Marc Arsicault ◽  
Jean-Michel Guilhem
Keyword(s):  
Musculoskeletal Disorder ◽  
Doppler Sonography ◽  
Impact Force ◽  
Variable Stiffness ◽  
Safety Performance ◽  
End Effector ◽  
Force Criterion ◽  
Compliant Joint ◽  
The Impact ◽  
Collaborative Robot

This paper deals with a collaborative robot, i.e., cobot, coupled with a new prismatic compliant joint (PCJ) at its end-effector. The proposed collaborative solution is intended for Doppler sonography to prevent musculoskeletal disorders issues. On one hand, the Doppler sonographer’s postures are investigated based on motion capture use during the arteries examination. This study highlighted that configurations adopted by angiologists lead to the musculoskeletal disorder. On the other hand, the proposed PCJ with variable stiffness gives an intrinsic compliance to the cobot handling the probe. This feature allows preserving the human safety when both human and cobot share a common workspace. The effectiveness of the proposed solution is experimentally validated through a 7-DoF Franka Emika robot virtually coupled with the PCJ, during the execution of a trajectory performed during a Doppler ultrasound exam. The impact force criterion is considered as a safety performance.

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.

An experimental comparison of the pedestrian safety performances of a spring actuator and a pyrotechnic actuator for deploying an active hood lift system

2017 ◽  
Vol 231 (7) ◽  
pp. 973-983 ◽  
Author(s):  
Tae-Hoon Lee ◽  
Gun-Ha Yoon ◽  
Je-Won Kang ◽  
Seung-Bok Choi
Keyword(s):  
Impact Force ◽  
Pedestrian Safety ◽  
Safety Performance ◽  
Experimental Comparison ◽  
Passenger Vehicle ◽  
Protection Effect ◽  
Working Principle ◽  
Deployment Time ◽  
The Impact ◽  
System Time

This research experimentally investigates the pedestrian safety performance of an active hood lift system of a passenger vehicle by adopting two different actuators: a spring actuator and a pyrotechnic actuator (gunpowder). After briefly introducing the working principle of the active hood lift system with the two different actuators, experiments to measure the deployment time of the system are carried out to evaluate the pedestrian safety. Subsequently, headform impact tests on the hood are performed to generate the impact force, and hence the mitigation of pedestrian injuries is investigated for the two different actuators. By comparing the measured performances obtained from both actuators, it is shown that the pyrotechnic actuator can provide a faster deployment system time. It is also identified that the spring actuator can provide a better safety performance for protecting adult pedestrians, whereas the safety performance of the pyrotechnic actuator is relatively low. Consequently, the pyrotechnic actuator is redesigned and manufactured to improve its safety performance and tested again. Then, it is shown that the modified pyrotechnic actuator can provide a better protection effect for an adult pedestrian than the spring actuator can.

Stiffness Design for a Spatial Three Degrees of Freedom Serial Compliant Manipulator Based on Impact Configuration Decomposition

2012 ◽  
Vol 5 (1) ◽  
Author(s):  
Dongming Gan ◽  
Nikos G. Tsagarakis ◽  
Jian S. Dai ◽  
Darwin G. Caldwell ◽  
Lakmal Seneviratne
Keyword(s):  
Degrees Of Freedom ◽  
General Procedure ◽  
Joint Torque ◽  
End Effector ◽  
Joint Torques ◽  
Serial Manipulators ◽  
Stiffness Design ◽  
Compliant Joint ◽  
The Impact ◽  
Three Degrees Of Freedom

This paper proposes a method of stiffness design for a spatial Three Degrees of Freedom (3DOF) serial compliant manipulator with the objective of protecting the compliant joint actuators when the manipulator comes up against impact. System dynamic equations of serial compliant manipulators integrated with an impact model are linearized to identify the maximum joint torques in the impact. Based on this, a general procedure is given in which maximum joint torques are calculated with different directions of end-effector velocity and impact normal in the manipulator workspace based on a given magnitude of end-effector velocity. By tuning the stiffness for each compliant joint to ensure the maximum joint torque does not exceed the maximum value of the actuator, candidate stiffness values are obtained to make the compliant actuators safe in all cases. The theory and procedure are then applied to the spatial 3DOF serial compliant manipulator of which the impact configuration is decomposed into a 2DOF planar serial manipulator and a 1DOF manipulator with a 2DOF link based on the linearized impact-dynamic model. Candidate stiffness of the 3DOF serial compliant manipulator is obtained by combining analysis of the 2DOF and 1DOF manipulators. The method introduced in this paper can be used for both planar and spatial compliant serial manipulators.

scholarly journals Toward Tradeoff Between Impact Force Reduction and Maximum Safe Speed: Dynamic Parameter Optimization of Variable Stiffness Robots

2020 ◽  
Vol 12 (5) ◽  
Author(s):  
Siyang Song ◽  
Yu She ◽  
Junmin Wang ◽  
Hai-Jun Su
Keyword(s):  
Performance Measures ◽  
Impact Force ◽  
Variable Stiffness ◽  
Dynamic Parameter ◽  
Human Robot Interaction ◽  
Maximum Speed ◽  
Performance Indices ◽  
Global Performance ◽  
Force Reduction ◽  
The Impact

Abstract Variable stiffness robots may provide an effective way of trading-off between safety and speed during physical human–robot interaction. In such a compromise, the impact force reduction capability and maximum safe speed are two key performance measures. To quantitatively study how dynamic parameters such as mass, inertia, and stiffness affect these two performance measures, performance indices for impact force reduction capability and maximum speed of variable stiffness robots are proposed based on the impact ellipsoid in this paper. The proposed performance indices consider different impact directions and kinematic configurations in the large. Combining the two performance indices, the global performance of variable stiffness robots is defined. A two-step optimization method is designed to achieve this global performance. A two-link variable stiffness link robot example is provided to show the efficacy of the proposed method.

scholarly journals Impact Force Identification of the Variable Pressure Flexible Impact End-Effector in Space Debris Active Detumbling

2020 ◽  
Vol 10 (9) ◽  
pp. 3011
Author(s):  
Ziying Wei ◽  
Huibo Zhang ◽  
Baoshan Zhao ◽  
Xiaoang Liu ◽  
Rui Ma
Keyword(s):  
Space Debris ◽  
Impact Force ◽  
Pressure Change ◽  
Friction Model ◽  
Space Environment ◽  
Variable Pressure ◽  
Force Model ◽  
End Effector ◽  
Identification Error ◽  
The Impact

The security of the space environment is under serious threat due to the increase in space debris in orbit. The active removal of space debris could ensure the sustainable use of the space environment; this removal relies on detumbling technology. According to the characteristics of the mechanical impact-type active detumbling method, this paper discusses a method to accurately identify the impact force using a pressure sensor. In this work, the impact force between a flexible impact end-effector and the space debris was analyzed theoretically and experimentally considering the pressure change during impact. Firstly, a nonlinear impact force model was established for the impact between a flexible end-effector and space debris. Secondly, impact experiments were performed and the friction model was modified. Finally, the effect of detumbling was verified through simulation experiments. The results showed that the identification error of normal impact force was less than 6.7% and the identification error of tangential friction force was less than 6.9%. Therefore, this identification method of impact force met the requirements of space debris detumbling, which has important guiding significance for the active removal technology of space debris.

Stiffness Design for Compliant Manipulators Based on Dynamics Analysis of the Impact Configuration

2011 ◽  
Author(s):  
Dongming Gan ◽  
Nikos G. Tsagarakis ◽  
Jian S. Dai ◽  
Darwin G. Caldwell
Keyword(s):  
Joint Stiffness ◽  
Joint Torque ◽  
Dynamics Analysis ◽  
End Effector ◽  
Joint Torques ◽  
Maximum Value ◽  
Stiffness Design ◽  
Compliant Joint ◽  
Compliant Actuators ◽  
The Impact

This paper presents a study on setting the joint stiffness for compliant robots in order to protect the actuators when the arm comes up against impact. System dynamic equations of compliant manipulators integrated with impact model are linearized to identify the maximum joint torques in the impact. Based on this, different directions of end-effector velocity and impact normal in different configurations in the robot workspace are calculated based on a given magnitude of end-effector velocity. By tuning the stiffness for each compliant joint to ensure the joint torque does not exceed the maximum value of the actuator, candidate stiffness values are obtained to make the compliant actuators safe in all cases when the robot end-effector moves with a velocity within the fixed magnitude value used in the calculation. The theory and procedure are firstly laid and demonstrated in a 1-DOF planar manipulator, then the work is applied to a 2-DOF compliant manipulator and the candidate stiffness is obtained based on the method.

Some thought on the Estimating of the Impact Force by an Experiment

2019 ◽  
Vol 7 (2) ◽  
pp. 205-213
Author(s):  
Yong-Doo Kim ◽  
Seung-Jae Lim ◽  
Hyun-Ung Bae ◽  
Kyoung-Ju Kim ◽  
Chin-Ok Lee ◽  
...  
Keyword(s):  
Impact Force ◽  
The Impact

scholarly journals Sandwich panel with in-plane honeycombs in different Poisson's ratio under low to medium impact loads

2021 ◽  
Vol 60 (1) ◽  
pp. 145-157
Author(s):  
Yi Luo ◽  
Ke Yuan ◽  
Lumin Shen ◽  
Jiefu Liu
Keyword(s):  
Poisson’S Ratio ◽  
Sandwich Panel ◽  
Impact Force ◽  
Impact Resistance ◽  
Poisson's Ratio ◽  
Compression Performance ◽  
Post Impact ◽  
Local Impact ◽  
Collapse Behavior ◽  
The Impact

Abstract In this study, a series of in-plane hexagonal honeycombs with different Poisson's ratio induced by topological diversity are studied, considering re-entrant, semi-re-entrant and convex cells, respectively. The crushing strength of honeycomb in terms of Poisson's ratio is firstly presented. In the previous research, we have studied the compression performance of honeycomb with different negative Poisson's ratio. In this study, a comparative study on the local impact resistance of different sandwich panels is conducted by considering a spherical projectile with low to medium impact speed. Some critical criteria (i.e. local indentation profile, global deflection, impact force and energy absorption) are adopted to analyze the impact resistance. Finally, an influential mechanism of Poisson's ratio on the local impact resistance of sandwich panel is studied by considering the variation of core strength and post-impact collapse behavior.

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