An Innovative Mechanical Solution to Better Understand Human-Robot Interaction Forces

This paper presents the development of a framework based on a quasi-statics concept for modeling and analyzing the physical human-robot interaction in soft robotic hand exoskeletons used for rehabilitation and human performance augmentation. This framework provides both forward and inverse quasi-static formulations for the interaction between a soft robotic digit and a human finger which can be used for the calculation of angular motions, interaction forces, actuation torques, and stiffness at human joints. This is achieved by decoupling the dynamics of the soft robotic digit and the human finger with similar interaction forces acting on both sides. The presented theoretical models were validated by a series of numerical simulations based on a finite element model which replicates similar human-robot interaction. The comparison of the results obtained for the angular motion, interaction forces, and the estimated stiffness at the joints indicates the accuracy and effectiveness of the quasi-static models for predicting the human-robot interaction.

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Quantifying the human-robot interaction forces between a lower limb exoskeleton and healthy users

2016 38th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) ◽

10.1109/embc.2016.7590770 ◽

2016 ◽

Cited By ~ 15

Author(s):

Ashish Rathore ◽

Matthew Wilcox ◽

Dafne Zuleima Morgado Ramirez ◽

Rui Loureiro ◽

Tom Carlson

Keyword(s):

Lower Limb ◽

Human Robot Interaction ◽

Robot Interaction ◽

Interaction Forces ◽

Lower Limb Exoskeleton

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Polymer optical fiber-embedded, 3D-printed instrumented support for microclimate and human-robot interaction forces assessment

Optics & Laser Technology ◽

10.1016/j.optlastec.2018.11.044 ◽

2019 ◽

Vol 112 ◽

pp. 323-331 ◽

Cited By ~ 4

Author(s):

Arnaldo G. Leal-Junior ◽

Camilo R. Díaz ◽

Maria José Pontes ◽

Carlos Marques ◽

Anselmo Frizera

Keyword(s):

Optical Fiber ◽

Human Robot Interaction ◽

Polymer Optical Fiber ◽

Robot Interaction ◽

Interaction Forces ◽

3D Printed

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Proprioceptive Estimation of Forces Using Underactuated Fingers for Robot-Initiated pHRI

Sensors ◽

10.3390/s20102863 ◽

2020 ◽

Vol 20 (10) ◽

pp. 2863

Author(s):

Joaquin Ballesteros ◽

Francisco Pastor ◽

Jesús M. Gómez-de-Gabriel ◽

Juan M. Gandarias ◽

Alfonso J. García-Cerezo ◽

...

Keyword(s):

Frontal Plane ◽

Regression Method ◽

Human Robot Interaction ◽

Shared Control ◽

Joint Angles ◽

Current Position ◽

Robot Interaction ◽

Interaction Forces ◽

Processing Times ◽

Human Limb

In physical Human–Robot Interaction (pHRI), forces exerted by humans need to be estimated to accommodate robot commands to human constraints, preferences, and needs. This paper presents a method for the estimation of the interaction forces between a human and a robot using a gripper with proprioceptive sensing. Specifically, we measure forces exerted by a human limb grabbed by an underactuated gripper in a frontal plane using only the gripper’s own sensors. This is achieved via a regression method, trained with experimental data from the values of the phalanx angles and actuator signals. The proposed method is intended for adaptive shared control in limb manipulation. Although adding force sensors provides better performance, the results obtained are accurate enough for this application. This approach requires no additional hardware: it relies uniquely on the gripper motor feedback—current, position and torque—and joint angles. Also, it is computationally cheap, so processing times are low enough to allow continuous human-adapted pHRI for shared control.

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Variable Stiffness Mechanism for Suppressing Unintended Forces in Physical Human–Robot Interaction

Journal of Mechanisms and Robotics ◽

10.1115/1.4042295 ◽

2019 ◽

Vol 11 (2) ◽

Cited By ~ 3

Author(s):

Sri Sadhan Jujjavarapu ◽

Amirhossein H. Memar ◽

M. Amin Karami ◽

Ehsan T. Esfahani

Keyword(s):

High Frequency ◽

Degrees Of Freedom ◽

Variable Stiffness ◽

Human Robot Interaction ◽

Robot Interaction ◽

Interaction Forces ◽

Air Gaps ◽

Nonlinear Springs ◽

Controller Gain ◽

Unstable Interaction

This paper presents the design of a two-degrees-of-freedom (DoFs) variable stiffness mechanism and demonstrates how its adjustable compliance can enhance the robustness of physical human–robot interaction. Compliance on the grasp handle is achieved by suspending it in between magnets in preloaded repelling configuration to act as nonlinear springs. By adjusting the air gaps between the outer magnets, the stiffness of the mechanism in each direction can be adjusted independently. Moreover, the capability of the proposed design in suppressing unintended interaction forces is evaluated in two different experiments. In the first experiment, improper admittance controller gain leads to unstable interaction, whereas in the second case, high-frequency involuntary forces are caused by the tremor.

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Fiber Bragg Gratings in CYTOP Fibers Embedded in a 3D-Printed Flexible Support for Assessment of Human–Robot Interaction Forces

Materials ◽

10.3390/ma11112305 ◽

2018 ◽

Vol 11 (11) ◽

pp. 2305 ◽

Cited By ~ 13

Author(s):

Arnaldo Leal-Junior ◽

Antreas Theodosiou ◽

Camilo Díaz ◽

Carlos Marques ◽

Maria Pontes ◽

...

Keyword(s):

Thermoplastic Polyurethane ◽

Fiber Bragg Gratings ◽

Acrylonitrile Butadiene Styrene ◽

Bragg Gratings ◽

Interaction Force ◽

Human Robot Interaction ◽

Polymer Optical Fiber ◽

Robot Interaction ◽

Interaction Forces ◽

Flexible Support

We developed a flexible support with embedded polymer optical fiber (POF) sensors for the assessment of human–robot interaction forces. The supports were fabricated with a three-dimensional (3D) printer, where an acrylonitrile butadiene styrene (ABS) rigid structure was used in the region of the support in which the exoskeleton was attached, whereas a thermoplastic polyurethane (TPU) flexible structure was printed in the region where the users placed their legs. In addition, fiber Bragg gratings (FBGs), inscribed in low-loss, cyclic, transparent, optical polymer (CYTOP) using the direct-write, plane-by-plane femtosecond laser inscription method, were embedded in the TPU structure. In this case, a 2-FBG array was embedded in two supports for human–robot interaction force assessment at two points on the users’ legs. Both FBG sensors were characterized with respect to temperature and force; additionally, the creep response of the polymer, where temperature influences the force sensitivity, was analyzed. Following the characterization, a compensation method for the creep and temperature influence was derived, showing relative errors below 4.5%. Such errors were lower than the ones obtained with similar sensors in previously published works. The instrumented support was attached to an exoskeleton for knee rehabilitation exercises, where the human–robot interaction forces were measured in flexion and extension cycles.

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A Modular Design for Distributed Measurement of Human–Robot Interaction Forces in Wearable Devices

Sensors ◽

10.3390/s21041445 ◽

2021 ◽

Vol 21 (4) ◽

pp. 1445

Author(s):

Keya Ghonasgi ◽

Saad N. Yousaf ◽

Paria Esmatloo ◽

Ashish D. Deshpande

Keyword(s):

Modular Design ◽

Force Measurement ◽

Low Cost ◽

Wearable Devices ◽

Human Robot Interaction ◽

Force Transmission ◽

Robot Interaction ◽

Interaction Forces ◽

Distributed Measurement ◽

Reliable Solution

Measurement of interaction forces distributed across the attachment interface in wearable devices is critical for understanding ergonomic physical human–robot interaction (pHRI). The main challenges in sensorization of pHRI interfaces are (i) capturing the fine nature of force transmission from compliant human tissue onto rigid surfaces in the wearable device and (ii) utilizing a low-cost and easily implementable design that can be adapted for a variety of human interfaces. This paper addresses both challenges and presents a modular sensing panel that uses force-sensing resistors (FSRs) combined with robust electrical and mechanical integration principles that result in a reliable solution for distributed load measurement. The design is demonstrated through an upper-arm cuff, which uses 24 sensing panels, in conjunction with the Harmony exoskeleton. Validation of the design with controlled loading of the sensorized cuff proves the viability of FSRs in an interface sensing solution. Preliminary experiments with a human subject highlight the value of distributed interface force measurement in recognizing the factors that influence ergonomic pHRI and elucidating their effects. The modular design and low cost of the sensing panel lend themselves to extension of this approach for studying ergonomics in a variety of wearable applications with the goal of achieving safe, comfortable, and effective human–robot interaction.

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Sensing small interaction forces through proprioception

Scientific Reports ◽

10.1038/s41598-021-01112-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Fazlur Rashid ◽

Devin Burns ◽

Yun Seong Song

Keyword(s):

Muscle Contraction ◽

Interaction Force ◽

Initial Position ◽

Human Robot Interaction ◽

Human Interaction ◽

Physical Interaction ◽

Robot Interaction ◽

Interaction Forces ◽

Force Direction ◽

Human Motor

AbstractUnderstanding the human motor control strategy during physical interaction tasks is crucial for developing future robots for physical human–robot interaction (pHRI). In physical human–human interaction (pHHI), small interaction forces are known to convey their intent between the partners for effective motor communication. The aim of this work is to investigate what affects the human’s sensitivity to the externally applied interaction forces. The hypothesis is that one way the small interaction forces are sensed is through the movement of the arm and the resulting proprioceptive signals. A pHRI setup was used to provide small interaction forces to the hand of seated participants in one of four directions, while the participants were asked to identify the direction of the push while blindfolded. The result shows that participants’ ability to correctly report the direction of the interaction force was lower with low interaction force as well as with high muscle contraction. The sensitivity to the interaction force direction increased with the radial displacement of the participant’s hand from the initial position: the further they moved the more correct their responses were. It was also observed that the estimated stiffness of the arm varies with the level of muscle contraction and robot interaction force.

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