Calculating Support Reactions and Interaction Forces

Just as the sense of touch complements vision in various species, several robots could benefit from advanced tactile sensors, in particular when operating under poor visibility. A prominent tactile sense organ, frequently serving as a natural paragon for developing tactile sensors, is the vibrissae of, e.g., rats. Within this study, we present a vibrissa-inspired sensor concept for 3D object scanning and reconstruction to be exemplarily used in mobile robots. The setup consists of a highly flexible rod attached to a 3D force-torque transducer (measuring device). The scanning process is realized by translationally shifting the base of the rod relative to the object. Consequently, the rod sweeps over the object’s surface, undergoing large bending deflections. Then, the support reactions at the base of the rod are evaluated for contact localization. Presenting a method of theoretically generating these support reactions, we provide an important basis for future parameter studies. During scanning, lateral slip of the rod is not actively prevented, in contrast to literature. In this way, we demonstrate the suitability of the sensor for passively dragging it on a mobile robot. Experimental scanning sweeps using an artificial vibrissa (steel wire) of length 50 mm and a glass sphere as a test object with a diameter of 60 mm verify the theoretical results and serve as a proof of concept.

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Design and Development of an Upper Limb Rehabilitative Robot with Dual Functionality

Micromachines ◽

10.3390/mi12080870 ◽

2021 ◽

Vol 12 (8) ◽

pp. 870

Author(s):

Md Rasedul Islam ◽

Md Assad-Uz-Zaman ◽

Brahim Brahmi ◽

Yassine Bouteraa ◽

Inga Wang ◽

...

Keyword(s):

Upper Limb ◽

Research Work ◽

Human Robot Interaction ◽

Control Technique ◽

Upper Arm ◽

Interaction Forces ◽

End Effector ◽

Upper Limb Rehabilitation ◽

End Point ◽

Limb Rehabilitation

The design of an upper limb rehabilitation robot for post-stroke patients is considered a benchmark problem regarding improving functionality and ensuring better human–robot interaction (HRI). Existing upper limb robots perform either joint-based exercises (exoskeleton-type functionality) or end-point exercises (end-effector-type functionality). Patients may need both kinds of exercises, depending on the type, level, and degree of impairments. This work focused on designing and developing a seven-degrees-of-freedom (DoFs) upper-limb rehabilitation exoskeleton called ‘u-Rob’ that functions as both exoskeleton and end-effector types device. Furthermore, HRI can be improved by monitoring the interaction forces between the robot and the wearer. Existing upper limb robots lack the ability to monitor interaction forces during passive rehabilitation exercises; measuring upper arm forces is also absent in the existing devices. This research work aimed to develop an innovative sensorized upper arm cuff to measure the wearer’s interaction forces in the upper arm. A PID control technique was implemented for both joint-based and end-point exercises. The experimental results validated both types of functionality of the developed robot.

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Doxorubicin Encapsulation in Carbon Nanotubes Having Haeckelite or Stone–Wales Defects as Drug Carriers: A Molecular Dynamics Approach

Molecules ◽

10.3390/molecules26061586 ◽

2021 ◽

Vol 26 (6) ◽

pp. 1586

Author(s):

Leonor Contreras ◽

Ignacio Villarroel ◽

Camila Torres ◽

Roberto Rozas

Keyword(s):

Carbon Nanotubes ◽

Molecular Dynamics ◽

Drug Delivery Systems ◽

Nitrogen Doping ◽

Drug Carriers ◽

Acidic Ph ◽

Free Energies ◽

Interaction Forces ◽

Chiral Nanotubes ◽

Binding Free Energies

Doxorubicin (DOX), a recognized anticancer drug, forms stable associations with carbon nanotubes (CNTs). CNTs when properly functionalized have the ability to anchor directly in cancerous tumors where the release of the drug occurs thanks to the tumor slightly acidic pH. Herein, we study the armchair and zigzag CNTs with Stone–Wales (SW) defects to rank their ability to encapsulate DOX by determining the DOX-CNT binding free energies using the MM/PBSA and MM/GBSA methods implemented in AMBER16. We investigate also the chiral CNTs with haeckelite defects. Each haeckelite defect consists of a pair of square and octagonal rings. The armchair and zigzag CNT with SW defects and chiral nanotubes with haeckelite defects predict DOX-CNT interactions that depend on the length of the nanotube, the number of present defects and nitrogen doping. Chiral nanotubes having two haeckelite defects reveal a clear dependence on the nitrogen content with DOX-CNT interaction forces decreasing in the order 0N > 4N > 8N. These results contribute to a further understanding of drug-nanotube interactions and to the design of new drug delivery systems based on CNTs.

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Visual Representation of Sound Sources and Interaction Forces in a Teleoperation Interface for a Mobile Robot

Journal of Human-Robot Interaction ◽

10.5898/jhri.4.2.reveleau ◽

2015 ◽

Vol 4 (2) ◽

pp. 1 ◽

Cited By ~ 9

Author(s):

Aurélien Reveleau ◽

François Ferland ◽

Mathieu Labbé ◽

Dominic Létourneau ◽

François Michaud

Keyword(s):

Mobile Robot ◽

Visual Representation ◽

Sound Sources ◽

Interaction Forces

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Long-term performance of prestressed concrete continuous box girders in the natural environment

Canadian Journal of Civil Engineering ◽

10.1139/cjce-2018-0447 ◽

2020 ◽

Vol 47 (7) ◽

pp. 856-864

Author(s):

Guohui Cao ◽

Wang Zhang ◽

Jiaxing Hu ◽

Xirong Peng

Keyword(s):

Prestressed Concrete ◽

Load Test ◽

Time Dependent ◽

Material Strength ◽

Practical Calculation ◽

Box Girders ◽

Load Types ◽

In The Beginning ◽

Support Reactions

A long-term load test performed for 470 days on two two-span prestressed concrete (PC) continuous box girders is reported in this paper. Load types were selected as the test variates, and structural responses such as support reactions, deflections, and concrete strains were monitored. Simultaneously, affiliated experiments such as material strength, creep, and shrinkage tests were conducted to investigate the time-dependent performances of the materials. Data obtained from these tests showed that deflections, strains, and support reactions develop rapidly in the beginning and stabilize afterward; the reactions of mid- and end-supports decline and rise over time, respectively. Time-dependent patterns of deflections and support reactions were analyzed on the basis of an effective modulus method, and a practical calculation method for long-term deflections considering reaction redistributions was proposed. The effects of the service environment on the performance of PC girders were evaluated through an incremental analysis method.

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