Abstract

The R-Min robot is an intrinsically safe parallel manipulator dedicated to pick-and-place operations. The proposed architecture is based on a five-bar mechanism, with additional passive joints in order to obtain a planar seven-bar mechanism with two degrees of underactuation, allowing the robot to reconfigure in case of a collision. A preload bar is added between the base and the end-effector to constrain the additional degrees-of-freedom. This article presents an analysis of the workspace and of the safety performances of the R-Min robot, and it compares them with those of the five-bar mechanism, in order to evaluate the benefits of introducing underactuation in a parallel architecture to obtain intrinsically safer robots. The geometrico-static model of the R-Min robot is formulated as an optimization problem. The direct and inverse kinemato-static models are derived from the geometrico-static model and they allow to express the singularity conditions of the R-Min robot. An analysis of the singularity loci is carried out among the robot’s workspace. A controller based on the dynamic model is proposed and experimentally validated on a prototype of the R-Min robot. Finally, the safety performances of the R-Min robot are evaluated experimentally and they are compared with that of an equivalent five-bar mechanism, using the maximum impact force as a safety criteria in accordance with recent international standards.

References

1.
Robla-Gómez
,
S.
,
Becerra
,
V. M.
,
Llata
,
J. R.
,
Gonzalez-Sarabia
,
E.
,
Torre-Ferrero
,
C.
, and
Perez-Oria
,
J.
,
2017
, “
Working Together: A Review on Safe Human–Robot Collaboration in Industrial Environments
,”
IEEE Access
,
5
, pp.
26754
26773
.
2.
Vicentini
,
F.
,
2021
, “
Collaborative Robotics: A Survey
,”
ASME J. Mech. Des.
,
143
(
4
), p.
040802
.
3.
Bischoff
,
R.
,
Kurth
,
J.
,
Schreiber
,
G.
,
Koeppe
,
R.
,
Albu-Schäffer
,
A.
,
Beyer
,
A.
,
Eiberger
,
O.
,
Haddadin
,
S.
,
Stemmer
,
A.
,
Grunwald
,
G.
, and
Hirzinger
,
G.
,
2010
, “
The Kuka-Dlr Lightweight Robot Arm—A New Reference Platform for Robotics Research and Manufacturing
,”
ISR 2010 (41st International Symposium on Robotics) and ROBOTIK 2010 (6th German Conference on Robotics)
,
Munich, Germany
,
June 7–9
, pp.
1
8
.
4.
Kim
,
Y.-J.
,
2017
, “
Anthropomorphic Low-Inertia High-Stiffness Manipulator for High-Speed Safe Interaction
,”
IEEE Trans. Rob.
,
33
(
6
), pp.
1358
1374
.
5.
Tsumaki
,
Y.
,
Suzuki
,
Y.
,
Sasaki
,
N.
,
Obara
,
E.
, and
Kanazawa
,
S.
,
2018
, “
A 7-dof Wire-Driven Lightweight Arm With Wide Wrist Motion Range
,”
2018 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)
,
Madrid, Spain
,
Oct. 1–5
, pp.
1
9
.
6.
Pratt
,
G. A.
, and
Williamson
,
M. M.
,
1995
, “
Series Elastic Actuators
,”
Proceedings 1995 IEEE/RSJ International Conference on Intelligent Robots and Systems. Human Robot Interaction and Cooperative Robots
,
Pittsburgh, PA
,
Aug. 5–9
, Vol. 1, pp.
399
406
.
7.
Bicchi
,
A.
, and
Tonietti
,
G.
,
2004
, “
Fast and “Soft-Arm” Tactics [Robot Arm Design]
,”
IEEE Robot. Autom. Mag.
,
11
(
2
), pp.
22
33
.
8.
Zinn
,
M.
,
Roth
,
B.
,
Khatib
,
O.
, and
Salisbury
,
J. K.
,
2004
, “
A New Actuation Approach for Human Friendly Robot Design
,”
Int. J. Robot. Res.
,
23
(
4–5
), pp.
379
398
.
9.
Park
,
J.-J.
,
Kim
,
B.-S.
,
Song
,
J.-B.
, and
Kim
,
H.-S.
,
2008
, “
Safe Link Mechanism Based on Nonlinear Stiffness for Collision Safety
,”
Mech. Mach. Theory
,
43
(
10
), pp.
1332
1348
.
10.
Hyun
,
D.
,
Yang
,
H. S.
,
Park
,
J.
, and
Shim
,
Y.
,
2010
, “
Variable Stiffness Mechanism for Human-Friendly Robots
,”
Mech. Mach. Theory
,
45
(
6
), pp.
880
897
.
11.
López-Martínez
,
J.
,
Blanco-Claraco
,
J. L.
,
García-Vallejo
,
D.
, and
Giménez-Fernández
,
A.
,
2015
, “
Design and Analysis of a Flexible Linkage for Robot Safe Operation in Collaborative Scenarios
,”
Mech. Mach. Theory
,
92
, pp.
1
16
.
12.
Zhang
,
M.
,
Laliberté
,
T.
, and
Gosselin
,
C.
,
2016
, “
On the Design of Mechanically Safe Robots Based on Spatial Isotropic Force Modules and Torque Limiters
,”
Mech. Mach. Theory
,
105
, pp.
199
212
.
13.
Seriani
,
S.
,
Gallina
,
P.
,
Scalera
,
L.
, and
Lughi
,
V.
,
2018
, “
Development of N-DoF Preloaded Structures for Impact Mitigation in Cobots
,”
ASME J. Mech. Rob.
,
10
(
5
), p.
051009
.
14.
Lauzier
,
N.
, and
Gosselin
,
C.
,
2015
, “
A Comparison of the Effectiveness of Design Approaches for Human-Friendly Robots
,”
ASME J. Mech. Des.
,
137
(
8
), p.
082302
.
15.
Campa
,
F.
,
Diez
,
M.
,
Diaz-Caneja
,
D.
, and
Altuzarra
,
O.
,
2019
, “
A 2 Dof Continuum Parallel Robot for Pick & Place Collaborative Tasks
,”
Adv. Mech. Machine Sci.
, pp.
1979
1988
.
16.
Jeanneau
,
G.
,
Bégoc
,
V.
,
Briot
,
S.
, and
Goldsztejn
,
A.
,
2020
, “
R-min: A Fast Collaborative Underactuated Parallel Robot for Pick-and-Place Operations
,”
IEEE International Conference on Robotics and Automation (ICRA)
,
Paris, France
,
May 31–Aug. 1
, IEEE, pp.
10365
10371
.
17.
Versace
,
J.
,
1971
, “
A Review of the Severity Index
,”
Proceedigns of the 15th Stapp Car Crash Conference
, pp.
771
796
, SAE Technical Paper No. 710881.
18.
Haddadin
,
S.
,
Albu-Schäffer
,
A.
, and
Hirzinger
,
G.
,
2007
, “
Safety Evaluation of Physical Human-Robot Interaction via Crash-Testing
,”
Robotics: Science and Systems
,
Atlanta, GA
,
June 27–30
,
W.
Burgard
,
O.
Brock
, and
C.
Stachniss
, eds., Vol. 3, The MIT Press.
19.
Haddadin
,
S.
,
Albu-Schäffer
,
A.
, and
Hirzinger
,
G.
,
2008
, “
The Role of the Robot Mass and Velocity in Physical Human–Robot Interaction-Part I: Non-Constrained Blunt Impacts
,”
IEEE International Conference on Robotics and Automation
,
Pasadena, CA
,
May 19–23
, IEEE, pp.
1331
1338
.
20.
ISO/TC 299 : ISO/TS15066
,
2016
, “
Robots and Robotic Devices—Collaborative Robots
.”
Tech. Rep. ISO/TS15066, International Organization for Standardization, Tech. Rep.
21.
Melia
,
M.
,
Schmidt
,
M.
,
Geissler
,
B.
,
König
,
J.
,
Krahn
,
U.
,
Ottersbach
,
H. J.
,
Letzel
,
S.
, and
Muttray
,
A.
,
2015
, “
Measuring Mechanical Pain: The Refinement and Standardization of Pressure Pain Threshold Measurements
,”
Behav. Res. Methods
,
47
(
1
), pp.
216
227
.
22.
Yamada
,
Y.
,
Hirasawa
,
Y.
,
Huang
,
S.
, and
Umetani
,
Y.
,
1996
, “
Fail-Safe Human/Robot Contact in the Safety Space
,”
Proceedings 5th IEEE International Workshop on Robot and Human Communication
,
Tsukuba, Japan
,
Nov. 11–14
, pp.
59
64
.
23.
COVR
,
2021
, “
Test Robot Arm for Collision With Fixed Object (Measurement of Pressure Over Time)
,”
Tech. Rep. ROB-LIE-2, COVR Consortium
.
24.
COVR
,
2021
, “
Test Robot Arm for Collision With a Movable Object (Measurement of Pressure Over Time)
,”
Tech. Rep. ROB-LIE-1, COVR Consortium
.
25.
DGUV
,
2017
, “
Kollaboriende Roboter, Planung von Anlagen mit der Funktion ‘Leistungs- und Kraftbegrenzung’
,”
Tech. Rep. FB HM-080, DGUV.
26.
Birglen
,
L.
,
Laliberté
,
T.
, and
Gosselin
,
C. M.
,
2007
,
Underactuated Robotic Hands
,
Springer
.
27.
Jeanneau
,
G.
,
Bégoc
,
V.
, and
Briot
,
S.
,
2020
, “
Geometrico-Static Analysis of a New Collaborative Parallel Robot for Safe Physical Interaction
,”
Proceedings of the ASME 2020 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference
,
virtual online
, p. V010T10A067.
28.
Quennouelle
,
C.
, and
Gosselin
,
C.
,
2011
, “
Kinematostatic Modeling of Compliant Parallel Mechanisms
,”
Meccanica
,
46
(
1
), pp.
155
169
.
29.
Nocedal
,
J.
, and
Wright
,
S.
,
2006
,
Numerical Optimization
,
Springer Science & Business Media
.
30.
Black
,
C.
,
Till
,
J.
, and
Rucker
,
D.
,
2017
, “
Parallel Continuum Robots: Modeling, Analysis, and Actuation-Based Force Sensing
,”
IEEE Trans. Robot.
,
34
(
1
), pp.
29
47
.
31.
Briot
,
S.
, and
Goldsztejn
,
A.
,
2022
, “
Singularity Conditions for Continuum Parallel Robots
,”
IEEE Trans. Robot.
,
38
(
1
), pp.
507
525
.
32.
Merlet
,
J.
,
2006
, “
Jacobian, Manipulability, Condition Number, and Accuracy of Parallel Robots
,”
ASME J. Mech. Des.
,
128
(
1
), pp.
199
206
.
33.
Khalil
,
W.
, and
Dombre
,
E.
,
2002
, “
Chapter 14—Motion Control
,”
Modeling, Identification and Control of Robots
,
W.
Khalil
, and
E.
Dombre
, eds.,
Butterworth-Heinemann
,
Oxford
, pp.
347
376
.
34.
Briot
,
S.
, and
Khalil
,
W.
,
2015
,
Dynamics of Parallel Robots: From Rigid Bodies to Flexible Elements
, 1st ed.,
Springer International Publishing
,
Dordrecht
, pp.
147
149
.
35.
Herbster
,
S.
,
Behrens
,
R.
,
Elkmann
,
N.
,
Siciliano
,
B.
,
Laschi
,
C.
, and
Khatib
,
O.
,
2020
, “
A New Conversion Method to Evaluate the Hazard Potential of Collaborative Robots in Free Collisions
,”
International Symposium on Experimental Robotics
,
Malta
,
B.
Siciliano
,
C.
Laschi
, and
O.
Khatib
, eds., Springer International Publishing, pp.
222
232
.
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