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A model that captures the weak frequency sensitivity of elastic hysteretic damping is proposed for the time-domain simulation of structures with multiple degrees of freedom (MDOF) under free or forced vibration. The model is based on a recently proposed modification to the conventional single degree of freedom (SDOF) viscous damping model, utilising a correction factor computed based on the local instantaneous response to adjust the damping coefficient such that the dissipated energy remains insensitive to the frequency characteristics of the motion. The model compares favourably to the well-established viscous (incl. Collar’s frequency correction), Rayleigh and Reid MDOF models, is applicable to any type of loading and, unlike other classes of damping models, such as Rayleigh, modal, Bouc-Wen, Biot, and Collar/Neumark, does not require extensive calibration, knowledge of the past history of motion, or a priori knowledge of the excitation characteristics and frequency.

Currently, additive manufacturing (AM) technology has received significant attention from both academia and industry. AM is characterized by fabricating geometrically complex components in a layer-by-layer manner, and greatly reduces the geometric complexity restrictions compared with traditional manufacturing. As AM is no longer limited to the normal three degrees of freedom (DOF) (three-axis) systems, there are many new multi-DOF AM machines been developed with various aims. It is, therefore, necessary that a review of the topic with regard to multi-DOF AM is performed for future AM system development. This paper, focuses on reviewing publications related to multi-DOF AM according to the number of DOF on an AM machine. The major part of the paper aims to inspire both researchers and engineers to further develop and improve multi-DOF AM systems to achieve different goals. The final part of the paper discusses the findings together with future research directions.

Identification of bridge dynamic properties from moving vehicle responses presents several practical benefits. However, a problem that arises when working with vehicle responses for indirect bridge health monitoring is that the bridge dynamics may get low-pass filtered by the vehicle suspension dynamics, rendering the identification of higher bridge modes difficult. Instead, the contact-point (CP) response—response at the contact point of the vehicle with the bridge surface—is a superior alternative to the vehicle response for identifying the bridge modal features. In the $$\text {CP}$$ response, the vehicle dynamics is suppressed and the higher bridge modes are significantly enhanced, thus making it better suited for modal identification. Extracting the $$\text {CP}$$ response from vehicle response is, however, not straightforward for a multiple degrees of freedom (MDoF) vehicle model. In this study, a novel methodology is proposed to extract $$\text {CP}$$ acceleration from the measured vehicle acceleration using the knowledge of the $$\text {MDoF}$$ vehicle dynamics. The $$\text {CP}$$ acceleration is shown to act as a base-excited input to the test vehicle and is extracted via a joint input-state estimation procedure employing a Gaussian process latent force model (GPLFM). Numerical case studies are considered to assess the quality of the $$\text {CP}$$ acceleration estimated with the proposed approach. It is found that the proposed method performs well and the extracted $$\text {CP}$$ acceleration response is able to reduce the effect of vehicle dynamics and improve the prominence of higher bridge modes.

It is well-known that the responses of a structure are different when subjected to a static load or a sudden step load. The dynamic amplification factor (DAF), which is defined as the ratio of the amplitude of the vibratory response to the static response, is normally used to depict the dynamic effect. For a single-degree-of-freedom system (SDOF) subjected to a sudden dynamic load, the maximum value of DAF is 2. Many design guidelines therefore use 2 as an upper bound to consider the dynamic effect. For a civil engineering structure, which is normally a multiple-degrees-of-freedom (MDOF) system, the DAF may exceed 2 in certain circumstances. The adoption of 2 as the upper bond as suggested by the design guidelines therefore may lead to unsafe structural design. Very limited studies systematically investigate the DAF of a MDOF system. This study theoretically investigates the DAF of a MDOF system when it is subjected to a step load based on the fundamental theory of structural dynamics. The condition on which the DAF may exceed 2 is defined. Two numerical examples and one experimental study of a cable-stayed bridge subjected to sudden cable loss are presented to illustrate the problem.

A multiple-degree-of-freedom (multi-DOF) motor can constitute small-sized and lightweight systems capable of performing complicated motions. Furthermore, the prospects for applications to industrial instruments via a direct drive are promising. This study aimed to develop practical multi-DOF motors capable of performing high-power rotary and linear motions using conventional three-phase inverters. A motor that performs rotary and linear motions is proposed. First, a method is presented for installing a salient pole on a needle with magnets. The method facilitates the use of soft magnetic materials with low eddy-current loss as iron cores. This study demonstrated the effectiveness of the salient pole for increasing the electromagnetic force. The model is used to explain the interactive magnetic interference generated by the armature currents for rotational and translation motions.

The encoding in multiple degrees of freedom can effectively improve the performance of current quantum key distribution, but the collective channel noise reduces the security of these proposals. In this article, we propose a high capacity quantum key distribution with single-photon in polarization and spatial-mode degrees of freedom, and protect the quantum states against the general collective noise by error-rejection in two degrees of freedom and quantum channel multiplexing. The states transmission and measurements in the presented quantum key distribution can be realized deterministically. The security analysis under the intercept-measure-resend eavesdropping and controlled-NOT operation eavesdropping attacks is conducted to verify the security, and the secure key rate analysis proves the efficiency of our proposal. These advantages make our proposal useful in practical quantum communication under current experimental conditions.

Earthquake response mitigation of base-isolated (BI) buildings with a tuned mass damper (TMD) is investigated. Two-dimensional reinforced concrete buildings having multiple degrees of freedom are n...

This paper presents the design, fabrication, and testing of a novel three-dimensional (3D) three-fingered electrothermal microgripper with multiple degrees of freedom (multi DOFs). Each finger of the microgripper is composed of a V-shaped electrothermal actuator providing one DOF, and a 3D U-shaped electrothermal actuator offering two DOFs in the plane perpendicular to the movement of the V-shaped actuator. As a result, each finger possesses 3D mobilities with three DOFs. Each beam of the actuators is heated externally with the polyimide film. The durability of the polyimide film is tested under different voltages. The static and dynamic properties of the finger are also tested. Experiments show that not only can the microgripper pick and place microobjects, such as micro balls and even highly deformable zebrafish embryos, but can also rotate them in 3D space.

Elastic valley metamaterials offer an excellent platform to manipulate elastic waves and have potential applications in energy harvesting and elastography. Here we introduce a series of strategies to realize a topological transition in spiral elastic valley metamaterials by parameter modulations. We show the evolution of the Berry curvature and valley Chern number as a function of inherent parameters of a spiral, which further results in a general scheme to achieve topological valley edge states. Our strategy leverages multiple degrees of freedom in spiral elastic valley metamaterials to provide enhanced opportunities for desired topological states.

Inspired by common patterns of biological movement, a series of near-infrared (NIR) laser-driven bionic intelligent hydrogel actuators were successfully fabricated via the combination of infiltration method (entirety infiltration and locality infiltration), structure design and material characteristics. The controllable distribution of graphene oxide (GO) particles in a hydrogel matrix resulting from the infiltration method led to abundant bionic deformations with multiple degrees of freedom and flexibility. In addition to the highest response speed of 187.7°/s, the hydrogel actuators underwent accurate and repeatable static deformations and efficient and stabilized dynamic locomotion, demonstrated, for example, through the assembly of origami, the deformation of fingers and palm, the closing and blooming of a chrysanthemum and the crawling of an inchworm. This study opens a new path for practical bionic applications of NIR-triggered hydrogel actuators in self-assembly biosensor, targeted drug delivery and minimally invasive surgery.

Developing robotic manipulators capable of performing effective physical interaction tasks is a challenging topic. In this study, we design a soft robotic arm (SRA) with multiple degrees of freedom inspired by the flexible structures and the unique motion mechanism of the octopus arm. The SRA is fabricated with elastomeric materials, which consists of four series of integrated pneumatic chambers that play similar roles as the muscles in the octopus arm can achieve large bending in various directions with variable stiffness. This SRA displays specified movements via controlling pressure and selecting channels. Moreover, utilizing parallel control, the SRA demonstrates complicated three-dimensional motions. The force response and motion of the SRA are determined both experimentally and computationally. The applications of the present SRA include tightly coiling around the objects because of its large bending deformation (nearly $$360^{{\circ }})$$ , grasping multiple objects, and adjusting the grabbing mode in accordance with the shape of objects.

Origami, also known as paper folding, has shown its potential to construct 3D structures from designed crease patterns on a flat sheet. This paper proposes a method to design axisymmetric 3D origami with generic six-crease bases. Inspired by the conventional six-crease bases, i.e., waterbomb base or Yoshimura base, where six regular crease lines meet at an interior vertex, we generalize the generic base so that the lengths of the crease lines can be regular or irregular. This method is based on designing the crease patterns. First, we interactively generate a crease pattern consisting of such generic bases. Then, our method analytically calculates the 3D origami shape with an axisymmetric structure. We demonstrate various configurations, i.e., sets of input parameters, to explore the variations of the calculated 3D origami. The 3D origami can have multiple degrees of freedom, but by continually changing one parameter we present a motion that can axisymmetrically deploy or flatten the shape. The method for designing 3D origami has potential applications ranging from self-folding tessellations to deployable architectures.

With the evolution of technology, it is now possible to build more flexible surgical instruments with multiple degrees of freedom that can be deployed in natural orifice translumenal endoscopic surgery, further reducing tissue damage, blood loss, and recovery time. However, the limits of flexible robots are mainly represented by the lack of accurate position feedback during the surgical procedure. The most critical problems of shape sensors are size and quantity limits, as well as sterilizability. This paper presents a novel helical configuration of single optic fiber with multiple fiber Bragg grating sensors to measure the shape of flexible robots. Detailed design of helix parameters, simulation and verification experiments were performed. We have shown the feasibility of helical configuration to reduce the effect of temperature, and detect the torsion and bending of the flexible shaft. The experimental results demonstrated the potential to provide a shape detection for flexible robot.

A multivariable approach of modeling and feedforward control of rate-independent hysteresis in multi-dof piezoelectric actuators is proposed in this paper. For that, the classical Prandtl–Ishlinskii (CPI) hysteresis model is extended into multivariable. Then, based on the inverse multiplicative structure and on the multivariable CPI model, a compensator is suggested. The proposed compensator does not require an extra-calculation: As soon as the model is identified, the compensator is obtained by structure. Furthermore, inversion of the model is avoided. Additionally to the hysteresis suppression, the multivariable compensator permits to reduce the cross-couplings between the axes which is not possible with standard techniques. The modeling and the inversion-free compensator are afterward applied to a two-degrees-of-freedom (2-dof) piezoactuator. The extensive investigated experimental tests demonstrate that the strong cross-couplings and the strong hysteresis in the two axes can be substantially reduced and linearized, respectively.

Continuum robots have attracted increasing attention from robotic community due to their intrinsic compliance and high dexterity. However, the compliant body structures and multiple degrees of freedom (DOFs) make it difficult for operators to intuitively regulate the configuration of continuum robots. Therefore, this paper presents a rod-driven continuum robot with teleoperation device achieving master-slave control. The master articulated manipulator has the same number of joints as the slave continuum robot. The slave continuum robot is equipped with two continuum joints with elastic backbones. Each joint possesses two DOFs and is driven by three elastic rods. The configuration parameters of the master manipulator are acquired by embedded sensors and return to a host computer. After kinematics calculating, the control command is sent to the slave continuum robot, to reproduce the configuration of the master manipulator. Experimental results show that the robotic system can achieve good master-slave following performance.

In this paper, a morphing carbon fibre composite aerofoil concept with an active trailing edge is proposed. This aerofoil features of camber morphing with multiple degrees of freedom. The shape morphing is enabled by an innovative structure driven by an electrical actuation system that uses linear ultrasonic motors (LUSM) with compliant runners, enabling full control of multiple degrees of freedom. The compliant runners also serve as structural components that carry the aerodynamic load and maintain a smooth skin curvature. The morphing structure with compliant truss is shown to exhibit a satisfactory flexibility and loading capacity in both numerical simulations and static loading tests. This design is capable of providing a pitching moment control independent of lift and higher L/D ratios within a wider angle-of-attack range. Such multiple morphing configurations could expand the flight envelope of future unmanned aerial vehicles. A small prototype is built to illustrate the concept, but as no off-the-shelf LUSMs can be integrated into this benchtop model, two servos are employed as actuators, providing two controlled degrees of freedom. This paper received a Written Paper Prize - Bronze Award from the Royal Aeronautical Society in 2018.

Reconfigurable devices, whose shape can be drastically altered, are central to expandable shelters, deployable space structures, reversible encapsulation systems and medical tools and robots. All these applications require structures whose shape can be actively controlled, both for deployment and to conform to the surrounding environment. While most current reconfigurable designs are application specific, here we present a mechanical metamaterial with tunable shape, volume and stiffness. Our approach exploits a simple modular origami-like design consisting of rigid faces and hinges, which are connected to form a periodic structure consisting of extruded cubes. We show both analytically and experimentally that the transformable metamaterial has three degrees of freedom, which can be actively deformed into numerous specific shapes through embedded actuation. The proposed metamaterial can be used to realize transformable structures with arbitrary architectures, highlighting a robust strategy for the design of reconfigurable devices over a wide range of length scales., Typically, most structures and devices that can be reconfigured are designed with application specific requirements. Inspired by modular origami ideas, Overvelde et al. present a mechanical metamaterial enabling the design of three-dimensional structures of arbitrary architecture with tunable shape, volume and stiffness.

If a picture tells a thousand words, then we might ask ourselves how many photons does it take to form a picture? In terms of the transmission of the picture information, then the multiple degrees of freedom (e.g., wavelength, polarization, and spatial mode) of the photon mean that high amounts of information can be encoded such that the many pixel values of an image can, in principle, be communicated by a single photon. However, the number of photons required to transmit the image information is not necessarily, at least technically, the same as the number of photons required to image an object. Therefore, another equally important question is how many photons does it take to measure an unknown image?

International audience; Recent technological advancements in augmented and mixed reality devices opened up many opportunities to users to interact in their environments. However, there are many unanswered questions about the definition of these interaction paradigms. In this article, we present a new approach to interact in these environments: using the body as a physical support to constrain the movement of a multiple degrees of freedom device (3D Mouse). This mouse offers enough degrees of freedom as well as a necessary accuracy to support the interaction. The use of the body as a support for the interaction allows the user to move in his environment and avoids the inherent fatigue of mid-air interactions. Thus, we propose a new design space for tangible interactions on the body, and specifically on theforearm. To validate the feasibility of such an approach, we present an experiment aimed at establishing the range, stability and comfort of gestures performed with a multiple degrees of freedom mouse on the forearm.; Les récents avènements technologiques au travers des périphériques de réalité augmenté ou mixte ouvrent de nombreuses opportunités aux utilisateurs pour interagir dans leurs environnements. Cependant, il reste de nombreuses questions sur la définition de ces paradigmes d’interaction. Dans cet article, nous présentons une nouvelle approche avec l’utilisation du corps comme support physique pour contraindre les déplacements d’un périphérique de type souris 3D. Cette souris offre suffisamment de degrés de liberté et une précision satisfaisante pour supporter l’interaction. L’utilisation du corps comme support à l’interaction permet à l’utilisateur de se déplacer dans son environnement et réduit la fatigue inhérente à l’interaction en l’air. Ainsi, nous proposons un nouvel espace de conception pour les interactions tangibles sur le corps, et en particulier sur l’avant-bras. Pour valider la faisabilité d’une telle approche, nous présentons une expérience visant à établir la portée, stabilité et confort des gestes effectués avec une souris 3D sur l’avant-bras.

Optical information security techniques are developed at a fast pace over the past two decades. In the present scenario, where enormous amount of data is being exchanged, information security plays an important role in protecting the information/data from unauthorized use/access. In this context, securing information using optical means has become relevant, given the suitable features of speed and multiple degrees of freedom that optical cryptosystems offer. Asymmetric cryptosystems have been introduced as an upgrade over the conventional double random phase encoding technique and they show resistance towards the known-plaintext attack. This paper reviews the symmetric and asymmetric cryptosystems and their attack analysis.

International audience; We present an application of the input shaping technique on infinite dimensional systems such as systems described by PDEs. The presented method is a feedforward scheme which allows to target multiple modes of a flexible system and also provide robustness with respect to parameters variations. The method is based on recently developed input shaper with multiple degrees of freedom that are needed to meet all constraints for the given task. We show that, even though the system consists of infinitely many modes, it is required to target only dominant ones. In addition, the method is illustrated on a case example of oil well drilling.

With rapid development of assistive technologies, robots have been adopted to assist impaired persons to perform daily functions. To increase functionality of robotic arm in grasping, a universal robotic gripper consists of multiple degrees of freedom (DOF) is proposed and examined in this paper. Through modelling, simulation, and mechatronics integration, the proposed gripper design is validated to be able to morph its shape to adapt objects with various shapes. Compliance of the gripper in grasping is also validated, which can increase the safety should it be included in assistive devices.

We developed a new technique for measuring the thermodynamic entropy as a function of the magnetic field angle. This technique enables high-resolution angle-resolved measurements of the entropy in an unprecedentedly short measuring time. When the magnetic field is rotated under adiabatic conditions, the sample temperature changes owing to the field-angle variation of its entropy, which is referred to as the rotational magnetocaloric effect. By investigating this effect along with the specific heat, the field-angle dependence of the entropy can be determined. To demonstrate this technique, we chose the spin-ice compound Dy$_2$Ti$_2$O$_7$ as a benchmark and showed good agreement between the measured and theoretical entropies as a function of the field angle. This development provides a new approach to studying condensed-matter physics, in which multiple degrees of freedom play an important role., 5 pages, 6 figures, published in J. Phys. Soc. Jpn

The Feature Selective Validation (FSV) method is both a de factor and de jure standard for comparing data for validation of computational electromagnetics in the EMC domain. However, the “domain agnostic” approach means that it is also seeing application outside its initial area of application. The focus of development was mostly on comparisons of, or with, numerical data but the potential application to measured data was proposed but has not been fully investigated. This paper addresses radio frequency EMC characterization applications of FSV with a view to assessing its suitability for a new IEEE Standards Project, P2665, “Statistical Process Control for EMC Test Laboratories”. The conclusions are that the FSV technique may, indeed, provide a suitable objective comparison method for visually complex data or for data that requires comparison with multiple degrees of freedom but further analysis is required in order to define the clear limits of operation.

By treating coherence as a shareable resource between multiple degrees of freedom (DoFs), we experimentally demonstrate a reversible exchange of coherence between polarization and spatial DoFs using only unitary transformations.

Piezoelectric actuators play huge role in positioning field and take micro technology to the new level. Micro positioning stages using piezoelectric actuators make it possible to enhance micro-technology. They are the key devices in micro management. This paper presents design and simulation of PZT XY-microstage with multiple degrees of freedom. This XY-Microstage has a high precision positioning. The whole structure is arranged in a symmetrical manner made up of silicon having dimension 20mm×20mm×0.4mm. All PZT actuators can be driven individually, results deflection of a micro stage in different directions. Two actuation units with Moonie amplification mechanism are integrated into the structure. Each actuation unit has the command or control on whole structure for movement in the desired direction. The performances of the XY-Microstage are simulated with the help of Finite Element Method of COMSOL Multiphysics.

We present a 3D user interface for collaborative manipulation of three-dimensional objects in virtual environments. It maps inertial sensors, touch screen and physical buttons of a mobile phone into well-known gestures to alter the position, rotation and scale of virtual objects. As these transformations require the control of multiple degrees of freedom (DOFs), collaboration is proposed as a solution to coordinate the modification of each and all the available DOFs. Users are free to decide their own manipulation roles. All virtual elements are displayed in a single shared screen, which is handy to aggregate multiple users in the same physical space.

Epitaxial heterostructures composed of complex oxides have fascinated researchers for over a decade as they offer multiple degrees of freedom to unveil emergent many-body phenomena often unattainable in bulk. Recently, apart from stabilizing such artificial structures along the conventional [001]-direction, tuning the growth direction along unconventional crystallographic axes has been highlighted as a promising route to realize novel quantum many-body phases. Here we illustrate this rapidly developing field of geometrical lattice engineering with the emphasis on a few prototypical examples of the recent experimental efforts to design complex oxide heterostructures along the (111) orientation for quantum phase discovery and potential applications.

This chapter focuses on a patient self-controlled rehabilitation system using our developed exoskeleton-type hand-motion-assist robot and tele-rehabilitation. The virtual reality-enhanced new hand rehabilitation support system, which we have developed for stroke patients in the acute stage, is aiming to allow such patients to conduct every day exercises by themselves without supervisors. This system features a multi-DOF motion assistance device, a virtual reality interface for patients, and a symmetrical master-slave motion assistance training strategy called ”self-motion control”, in which the stroke patients' healthy hand on the master side creates the assistance motion for the impaired hand on the slave side. Moreover, a tele-rehabilitation system consisting of a hand rehabilitation support system for the patients, an anthropomorphic robot hand for the therapist, and a remote monitoring system for diagnosing the degree of recovery is explained.

Drosophila melanogaster has been studied to gain insight into relationships between neural circuits and learning behaviour. To test models of their neural circuits, a robot that mimics D. melanogaster larvae has been designed. The robot is made from silicone by casting in 3D printed moulds with a pattern simplified from the larval muscle system. The pattern forms air chambers that function as pneumatic muscles to actuate the robot. A pneumatic control system has been designed to enable control of the multiple degrees of freedom. With the flexible body and multiple degrees of freedom, the robot has the potential to resemble motions of D. melanogaster larvae, although it remains difficult to obtain accurate control of deformation.

Soft robots are an interesting alternative for classic rigid robots in applications requiring interaction with organisms or delicate objects. Elastic inflatable actuators are one of the preferred actuation mechanisms for soft robots since they are intrinsically safe and soft. However, these pneumatic actuators each require a dedicated pressure supply and valve to drive and control their actuation sequence. Because of the relatively large size of pressure supplies and valves compared to electrical leads and electronic controllers, tethering pneumatic soft robots with multiple degrees of freedom is bulky and unpractical. Here, a new approach is described to embed hardware intelligence in soft robots where multiple actuators are attached to the same pressure supply, and their actuation sequence is programmed by the interaction between nonlinear actuators and passive flow restrictions. How to model this hardware sequencing is discussed, and it is demonstrated on an 8-degree-of-freedom walking robot where each limb comprises two actuators with a sequence embedded in their hardware. The robot is able to carry pay loads of 800 g in addition to its own weight and is able to walk at travel speeds of 3 body lengths per minute, without the need for complex on-board valves or bulky tethers. ispartof: ADVANCED MATERIALS vol:31 issue:3 ispartof: location:Germany status: published

During the last few decades, substantial scientific and technological efforts have been focused on the development of neuroprostheses. The major emphasis has been on techniques for connecting the human nervous system with a robotic prosthesis via natural-feeling interfaces. The peripheral nerves provide access to highly processed and segregated neural command signals from the brain that can in principle be used to determine user intent and control muscles. If these signals could be used, they might allow near-natural and intuitive control of prosthetic limbs with multiple degrees of freedom. This review summarizes the history of neuroprosthetic interfaces and their ability to record from and stimulate peripheral nerves. We also discuss the types of interfaces available and their applications, the kinds of peripheral nerve signals that are used, and the algorithms used to decode them. Finally, we explore the prospects for future development in this area.

Galleries are common structures to protect roads and railways from rockfall hazards. The design concepts in recent guidelines are based on the application of a static equivalent impact force. This approach is simple to use for practicing engineers. However, the dynamic behavior of the structure is not adequately taken into consideration. An analytical model based on a system of multiple degrees of freedom is proposed, which enables predicting shear and bending failure of the gallery due to the impact of a falling block of rock. Several simplifications allow numerically solving the basic equations by means of a spreadsheet. In large-scale tests reinforced concrete slabs, measuring 3,5 m × 4,5 m and with two different thicknesses, were subjected to increasing impact loads up to failure. The measured decelerations in the block and the reaction forces at the supports provide the required data to verify the analytical model. The evaluation of an existing structure shows that for dimensions of average Swiss galleries failure is governed by punching shear.

We present the real time simultaneous and proportional control of two degrees of freedom (DoF), using surface electromyographic signals from the residual limbs of three subject with limb deficiency. Three subjects could control a virtual object in two dimensions using their residual muscle activities to achieve goal-oriented tasks. The subjects indicated that they found the control intuitive and useful. These results show that such a simultaneous and proportional control paradigm is a promising direction for multi-functional prosthetic control.

Myoelectric control is known since decades. Academic methods are usually based on the supervised classification of electromyographic (EMG) signals into a set of pre-defined functions. Therefore, such methods are sequential and non-proportional. In this talk, novel approaches based on the simultaneous and proportional control of multiple degrees of freedom using EMG will be presented. These methods can be either based on supervised regression (e.g., artificial neural networks) or on EMG signal factorization. The latter method is particularly promising because it does not require training. Results of the application of the new control schemes for both able-bodied and amputee subjects will be presented.

Recently vortex coalescence was reported in superconducting Sr${}_{2}$RuO${}_{4}$ by several experimental groups for fields applied along the $c$ axis. We argue that Sr${}_{2}$RuO${}_{4}$ is a type-1.5 superconductor with long-range attractive, short-range repulsive intervortex interaction. The type-1.5 behavior stems from an interplay of the two orbital degrees of freedom describing this chiral superconductor together with the multiband nature of the superconductivity. These multiple degrees of freedom give rise to multiple coherence lengths, some larger and some smaller than the magnetic field penetration length, resulting in nonmonotonic intervortex forces.

This letter investigates simultaneous and proportional estimation of force in 2 degree-of-freedoms (DoFs) from intramuscular electromyography (EMG). Intramuscular EMG signals from three able-bodied subjects were recorded along with isometric forces in multiple DoF from the right arm. The association between five EMG features and force profiles was modeled using an artificial neural network. Correlation coefficients between the measured and the estimated forces were 0.85 ± 0.056 and 0.88 ± 0.05 without and with post processing, respectively. The results showed that force can be estimated in 2 DoFs with high accuracy and that the degree of performance depended on the force function (task) to be estimated.