Unexpected Contacts Research Articles

“RobOstrich” Manipulator: A Novel Mechanical Design and Control Based on the Anatomy and Behavior of an Ostrich Neck

Flexible manipulators have high degrees of freedom and deformability, enabling dexterous movements and allowing for unexpected contacts with the environment. Underactuated tendon-drive mechanisms are the most widely adopted because of their simplicity and effectiveness. However, they suffer from difficulty in modeling and in achieving dexterity and structural stability. In this paper, we focus on ostriches, which can dexterously and swiftly move their flexible necks. We carried out a detailed dissection of ostrich necks and identified a specific musculo-tendon-skeletal structure. Based on the findings related to the structure, we came up with a novel mechanical design and control method manifested as a “RobOstrich” manipulator. Our actual robot experiments confirm that it exhibits similar movement patterns as an ostrich neck. It is also flexible yet structurally stable, enabling dexterous reaching movements. This work also contributes to biology by providing constructive understanding of the functionality of the morphology of an ostrich neck.

ARC Joint: Anthropomorphic Rolling Contact Joint With Kinematically Variable Torsional Stiffness

As compliant joints not only compensate for the lack of actuated degrees of freedom of an under-actuated system and improve grasp stability but also prevent system failure from unexpected contacts, various types of compliant joints have been applied to end-effectors. Although joint compliance increases the success rate of power grasping, when the finger wraps around large objects, it can reduce the grasping success rate in pinch gripping when dealing with small objects using the fingertips. To overcome this drawback, we propose a novel rolling contact joint, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">anthropomorphic rolling contact joint</i> , that mimicked the structures of the human finger joint, tongue-and-groove, and collateral ligaments. The anthropomorphic rolling contact joint can passively adjust the torsional stiffness according to the joint angle without additional weight and space. With the anthropomorphic rolling contact joint, flexing the fingers for pinch grasping increases torsional stiffness of the joints and improves grasping stability. In this study, the characteristics and performance of anthropomorphic rolling contact joints were experimentally analyzed by varying the tongue-and-groove shape. Furthermore, it was demonstrated that the three-finger gripper with high torsional stiffness stably grasps small objects in the pinch grasping posture. In addition, because it is easy to manufacture, an anthropomorphic rolling contact joint has advantages in terms of maintenance.

Development and validation of guidelines for safety in human-robot collaborative assembly systems

Industrial collaborative robotics is one of the most promising technologies of Industry 4.0. In particular, human-robot collaboration in assembly will be particularly interesting for manufacturing companies. In this context, the interaction between humans and robots opens new possibilities but also challenges. A major problem is related to safety: unwanted and unexpected contacts between the human and the robotic system may cause injuries and therefore limit the potential for collaboration. Nowadays, there is a lack of simple and practical tools for helping system designers in overcoming such limiting conditions. In this work, guidelines for the design of safe human-robot collaborative assembly are developed and classified, particularly focusing on the features characterizing the entire system. These are validated by means of a laboratory case study and a digital twin. The validation process is based on the assumption that a team of manufacturing engineers (not-experts in occupational health and safety) should be able to autonomously and gradually apply the given guidelines reducing the mechanical risk in a collaborative assembly system. The proposed solutions have been virtually modelled allowing the evaluation of their effectiveness. According to the results, the proposed guidelines effectively help non-expert users in the development and improvement of collaborative assembly systems from the safety perspective.

Project to Improve Satisfaction in the Conscription Physical Examinations Service

In response to a decrease in satisfaction to 69.3%, we resolved to optimize the process of conducting conscription physical examinations. After an investigatory panel conducted an analysis, the following problems were identified. Firstly, the poorly designed route lead to dense queues between exam stations. Secondly, the procedures for changing the dates of conscription physical examinations were cumbersome. Lastly, unexpected contacts between examinees and the patients in the hospital occurred from time to time, which increases the risk of cross infection. This project was developed to improve the level of satisfaction in conscription physical examinations and increase the quality of medical services provided. After brainstorming and reviewing the related literature, we identified several actions to address and resolve the problems. We adopted non-crossing lines, divided the servicemen's cabins for inspection, simplified the information system process, relocated the physical examination venue, and planned education and training. Satisfaction with the examination process increased from 69.3% to 90.3%. A survey-based review of the conscription physical examination process should be conducted annually to ensure the procedures are as smooth as possible and to improve the quality of medical services provided.

Omnidirectional Proximity Sensor System for Drones Using Optical Time‐of‐Flight Sensors

In recent years, the use of unmanned aerial vehicles, including drones, to conduct inspections has been attracting increasing attention. When a drone is used for inspections, it often approaches objects and obstacles, and its collision risk increases the closer it gets. In this study, we developed an omnidirectional proximity sensor system for drones using optical time‐of‐flight (ToF) sensors to avoid collisions. The sensor system consists of 87 ToF sensors that can estimate the distance between the sensors and objects. The ToF sensors are mounted on both the propeller guard of the drone and its body. Thus, they can measure objects horizontally, at ±45° Z direction, and above the drone. Further, the sensor system can detect objects around the drone in a noncontact area. Accordingly, the drone can be controlled using the measured data. Our results show that drones using the proposed sensor system can avoid unexpected contacts and collisions during flights. Consequently, we believe that the sensor system will be highly useful in drone operation. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Reconstruction of Backbone Curves for Snake Robots

Snake robots composed of alternating single-axis pitch and yaw joints have many internal degrees of freedom, which make them capable of versatile three-dimensional locomotion. In motion planning process, snake robot motions are often designed kinematically by a chronological sequence of continuous backbone curves that capture desired macroscopic shapes of the robot. However, as the geometric arrangement of single-axis rotary joints creates constraints on the rotations in the robot, it is challenging for the robot to reconstruct an arbitrary 3D curve. When the robot configuration does not accurately achieve the desired shapes defined by these backbone curves, the robot can have unexpected contacts with the environment, such that the robot does not achieve the desired motion. In this work, we propose a method for snake robots to reconstruct desired backbone curves by posing an optimization problem that exploits the robot's geometric structure. We verified that our method enables fast and accurate curve-configuration conversions through its applications to commonly used 3D gaits. We also demonstrated via robot experiments that 1) our method results in smooth locomotion on the robot; 2) our method allows the robot to approach the numerically predicted locomotive performance of a sequence of continuous backbone curve.

In-flight testing of the injection of the LISA Pathfinder test mass into a geodesic

LISA Pathfinder is a technology demonstrator space mission, aimed at testing key technologies for detecting gravitational waves in space. The mission is the precursor of LISA, the first space gravitational waves observatory, whose launch is scheduled for 2034. The LISA Pathfinder scientific payload includes two gravitational reference sensors (GRSs), each one containing a test mass (TM), which is the sensing body of the experiment. A mission critical task is to set each TM into a pure geodesic motion, i.e. guaranteeing an extremely low acceleration noise in the sub-Hertz frequency bandwidth. The grabbing positioning and release mechanism (GPRM), responsible for the injection of the TM into a geodesic trajectory, was widely tested on ground, with the limitations imposed by the 1-g environment. The experiments showed that the mechanism, working in its nominal conditions, is capable of releasing the TM into free-fall fulfilling the very strict constraint imposed on the TM residual velocity, in order to allow its capture on behalf of the electrostatic actuation.However, the first in-flight releases produced unexpected residual velocity components, for both the TMs. Moreover, all the residual velocity components were greater than maximum value set by the requirements. The main suspect is that unexpected contacts took place between the TM and the surroundings bodies. As a consequence, ad hoc manual release procedures had to be adopted for the few following injections performed during the nominal mission. These procedures still resulted in non compliant TM states which were captured only after impacts. However, such procedures seem not practicable for LISA, both for the limited repeatability of the system and for the unmanageable time lag of the telemetry/telecommand signals (about 4400 s). For this reason, at the end of the mission, the GPRM was deeply tested in-flight, performing a large number of releases, according to different strategies. The tests were carried out in order to understand the unexpected dynamics and limit its effects on the final injection. Some risk mitigation maneuvers have been tested aimed at minimizing the vibration of the system at the release and improving the alignment between the mechanism and the TM. However, no overall optimal release strategy to be implemented in LISA could be found, because the two GPRMs behaved differently.

CDC42 binds PAK4 via an extended GTPase-effector interface

The p21-activated kinase (PAK) group of serine/threonine kinases are downstream effectors of RHO GTPases and play important roles in regulation of the actin cytoskeleton, cell growth, survival, polarity, and development. Here we probe the interaction of the type II PAK, PAK4, with RHO GTPases. Using solution scattering we find that the full-length PAK4 heterodimer with CDC42 adopts primarily a compact organization. X-ray crystallography reveals the molecular nature of the interaction between PAK4 and CDC42 and shows that in addition to the canonical PAK4 CDC42/RAC interactive binding (CRIB) domain binding to CDC42 there are unexpected contacts involving the PAK4 kinase C-lobe, CDC42, and the PAK4 polybasic region. These additional interactions modulate kinase activity and increase the binding affinity of CDC42 for full-length PAK4 compared with the CRIB domain alone. We therefore show that the interaction of CDC42 with PAK4 can influence kinase activity in a previously unappreciated manner.

Carbohydrate–Polypeptide Contacts in the Antibody Receptor CD16A Identified through Solution NMR Spectroscopy

Asparagine-linked carbohydrates (N-glycans) are common modifications of eukaryotic proteins that confer multiple properties, including the essential stabilization of therapeutic monoclonal antibodies. Here we present a rapid and efficient strategy for identifying N-glycans that contact polypeptide residues and apply the method to profile the five N-glycans attached to the human antibody receptor CD16A (Fc γ receptor IIIA). Human embryonic kidney 293S cells expressed CD16A with 13CU-labeled N-glycans using standard protein expression techniques and medium supplemented with 3 g/L [13CU]glucose. Anomeric resonances on the protein-linked N-acetylglucosamine residue at the reducing end of the glycan are particularly well suited to studies of multiply glycosylated N-glycoproteins because only one reducing end and nitrogen-linked residue is present in each N-glycan. Correlations between anomeric 1H1 and 13C1 nuclei on the reducing end residue generate crosspeaks in a conventional two-dimensional heteronuclear single-quantum coherence nuclear magnetic resonance (NMR) experiment that appear in a region of the spectrum devoid of other carbohydrate peaks or background protein signals. Two N-glycan peaks corresponding to the N45 and N162 N-glycans were dispersed from the rapidly averaged peaks corresponding to the N38, N74, and N169 N-glycans. We used a combination of NMR and 1 μs all-atom computational simulations to identify unexpected contacts between the N45 N-glycan and CD16A polypeptide residues.

‘Scotland in Europe’: A Conference held in Kazimierz Dolny, Poland, 17–19 October 2012: Two voices

The very first mention of organising a ‘Scottish’ conference appeared quite a few years ago now, in June 2009, the occasion being the completion of my postdoctoral degree which I received from the University of Warsaw. The subject of my dissertation was ‘Translating Scotland. Nation and Identity’, an issue not touched upon earlier in Poland. The suggestion came from one of my reviewers, Professor David Malcolm from the University of Gdansk, one of our later highly colourful and amazingly talented conference participants. The idea lay dormant for quite a few months, only to appear again during a conversation with another reviewer of my work on Scotland, Jerzy Jarniewicz (University of Łodź), whose contribution in the initial organisational stages was extremely helpful. All three of us, from different academic centres in Poland, fully agreed on one thing, that it was high time a conference on Scotland, its languages, literature and culture, and its links with Europe was organised in this part of the world. This initiated what not only turned out to be an extremely interesting – albeit exhausting – venture, but also was the beginning of many unexpected academic contacts, fruitful cooperation and, most important, the realisation that there is an amazing number of individuals scattered around Poland and in many other parts of Europe who are, or have been, involved in Scottish issues. Our own academic involvement in translation also comes into this very strongly. Ideas evolved, support and agreement were received from our Head of Department, announcements were made, and invitations sent out. This also concerned the rather controversial decision on our part that, although it was a Warsaw University conference, the venue was to be 120 kilometres from the capital, in Kazimierz Dolny, a small, historical, and highly picturesque town in

Between horrid and science. Girolamo Segato's strange anatomy (1792-1836)

AbstractFascinating methods and materials for preserving dead bodies from decomposition were used by different populations in any time for various reasons. During the XVIII-XIX centuries, the necessity of preserving bodies increased, in order to improve anatomical studies, and many methods were developed. Girolamo Segato (1792-1836) devoted himself to the art of “petrifaction“, discovering a particular procedure, which permitted him to obtain amazing results. His sudden death prevented him from revealing his method: recent studies have disclosed unexpected contacts between Segato and American scientists, who were very interested in his work.

Knowledge-Based Elastic Potentials for Docking Drugs or Proteins with Nucleic Acids

Elastic ellipsoidal functions defined by the observed hydration patterns around the DNA bases provide a new basis for measuring the recognition of ligands in the grooves of double-helical structures. Here a set of knowledge-based potentials suitable for quantitative description of such behavior is extracted from the observed positions of water molecules and amino acid atoms that form hydrogen bonds with the nitrogenous bases in high resolution crystal structures. Energies based on the displacement of hydrogen-bonding sites on drugs in DNA-crystal complexes relative to the preferred locations of water binding around the heterocyclic bases are low, pointing to the reliability of the potentials and the apparent displacement of water molecules by drug atoms in these structures. The validity of the energy functions has been further examined in a series of sequence substitution studies based on the structures of DNA bound to polyamides that have been designed to recognize the minor-groove edges of Watson-Crick basepairs. The higher energies of binding to incorrect sequences superimposed (without conformational adjustment or displacement of polyamide ligands) on observed high resolution structures confirm the hypothesis that the drug subunits associate with specific DNA bases. The knowledge-based functions also account satisfactorily for the measured free energies of DNA-polyamide association in solution and the observed sites of polyamide binding on nucleosomal DNA. The computations are generally consistent with mechanisms by which minor-groove binding ligands are thought to recognize DNA basepairs. The calculations suggest that the asymmetric distributions of hydrogen-bond-forming atoms on the minor-groove edge of the basepairs may underlie ligand discrimination of G·C from C·G pairs, in addition to the commonly believed role of steric hindrance. The analysis of polyamide-bound nucleosomal structures reveals other discrepancies in the expected chemical design, including unexpected contacts to DNA and modified basepair targets of some ligands. The ellipsoidal potentials thus appear promising as a mathematical tool for the study of drug- and protein-DNA interactions and for gaining new insights into DNA-binding mechanisms.

A target-approachable force-guided control with adaptive accommodation for complex assembly

In this paper, a target approachable force-guided control with adaptive accommodation for complex assembly is presented. Complex assembly (CA) is defined as a task which deals with complex shaped parts including concavity, or whose environment is so complex that unexpected contacts occur frequently during insertion. CA tasks are encountered frequently in the field of manufacturing automation and various robot applications. To make CA successful, both the bounded wrench condition and the target approachability condition should be satisfied simultaneously during insertion. The bounded wrench condition can be satisfied by properly designing accommodation parameters, which depends on the tolerable stiffness for an assembly task, not to exceed the prescribed contact wrench. On the other hand, the target approachability condition can be satisfied by determining an admissible twist minimizing the deviation between the current and target twist. By applying convex optimization techniques, an optimum target approaching twist can be determined at each instantaneous contact state as a global minimum solution. Incorporated with an admissible perturbation method, a new CA algorithm using only the sensed resultant wrench and the target twist is developed without motion planning or contact analysis (which requires the geometry of the part and the environment). To verify the feasibility of the new assembly algorithm, a wench sensor model based on a minimum distance algorithm has been developed and used to estimate contact wrenches in graphic assembly simulation. Finally, a VME bus-based real-time control system is built for experiments on various CA tasks. The T-insertion task as a planar CA, and the double-peg assembly task as a spatial CA, were successfully executed by implementing the new force-guided control with adaptive accommodation.

Unexpected Contacts: Lithuanians at Western Courts, c. 1316-c. 1400

Unexpected Contacts: Lithuanians at Western Courts, c. 1316-c. 1400

Contact analysis and verification in a 2D environment with uncertainties

This contribution presents results of a research project concerned with the planning and execution of motions in uncertain environments. In particular, the problem of a moving convex polygon within an uncertain two-dimensional environment has been investigated. The essential sub-problem of how to analyse unexpected contacts is treated. Using a set-oriented model of the uncertainties, the motion possibilities of the polygon is investigated for the different contact types. Also based on the model of the uncertainties, the potential locations of the geometric elements are constructed and intersected, giving us the contact hypotheses. With the help of exploratory motions, an attempt is made to decide between ambiguous hypotheses. The question of which exploratory motions are useful for the different contact types is also investigated. After an exploratory motion has been executed, its results must be evaluated with respect to the validity of the hypotheses. The system has been implemented and is also described in this paper.