Search

A tendon-driven snake-arm robot can achieve a bending motion with multiple degrees of freedom (DOF) with a compact structure, which enables the robot to be widely used in confined environments. However, if a conventional tendon-driven snake-arm robot is subject to a lateral force on the distal end, it will experience passive compliance. In this paper, a 2-DOF rolling joint is proposed, based on the opposite-pole attraction of spherical magnets, which has a relatively simple structure compared with traditional joints. By serially connecting the 2-DOF rolling joints, a novel snake-arm robot is designed utilizing a tendon-driven approach. The kinematic model and workspace of the snake-arm robot are obtained, and the bending motion is validated. Based on the kinematic model, it is theoretically proven that the proposed robot can avoid passive compliance. In addition, this feature is verified through load experiments on the developed prototype.

A gear is used not only for power transmission but also in precision positioning. A conventional and general gear has only one degree of freedom motion. Therefore, the case of its use is limited. In this paper, we propose and manufacture an innovative spherical gear. The proposed spherical gear has a multiple degrees of freedom motion. Compared with other spherical gear, the proposed spherical gear does not have complex shape. Moreover, the handle of the proposed spherical gear is similar to that of a spur gear. The experimental apparatus using the spherical gear pair measures a transmission efficiency and an angular backlash between the gears. According to experimental results, the spherical gear teeth could mesh firmly and transmit power at any shaft angle. In addition, the maximum transmission efficiency and the angular backlash become about 87.1% and 16.9 mrad when the shaft angle is 0°, respectively.

Studies have developed various types of soft robotic gloves for hand rehabilitation in recent years. Most soft actuators achieved a sufficient thumb flexion assist while lacking opposition support, which requires the coordination of thumb flexion and abduction-adduction. The difficulties for thumb support lie in the intrinsic complexity of thumb movements and spatial restriction of the hand. To realize multiple degrees of freedom of the thumb and make effective use of the limited space of the hand's dorsal side, we optimized and compared two approaches for thumb support. The combination approach used two independent soft actuators for thumb flexion and abduction-adduction support, respectively. The all-in-one approach used one single soft actuator to assist motions in different directions. We designed the soft actuators for each approach based on the thumb's biomechanical characteristics and evaluated their thumb flexion, abduction support performance in terms of the range of motion (RoM) and force output, and the opposition support performance using an enhanced Kapandji test. The results showed a larger abduction RoM and force output of the composition approach and a higher Kapandji score of the all-in-one approach, indicating that the two approaches might be applicable for thumb support but have the advantage in different rehabilitation stages.

Performing a successful robotic grasping to uncertain objects in unstructured environments is challenging. This study presents a new compliant soft robotic gripper for objects handling and cap manipulation through the coordination of three soft fingers and in-hand manipulation. The experiments are conducted to validate that the soft robotic gripper can successfully realize simultaneous grasping and capping manipulations with only one flexible shaft actuation for every single soft finger. Note to Practitioners —Uncertain object manipulation tasks pose significant challenges to a robotic gripper while grasping and capping unknown objects without damaging them. The existing rigid grippers have experienced flexible manipulation through multiple degrees of freedom (DoFs) by complex mechanical structures, and the soft gripper can realize stiffness-compliant manipulation differently. The proposed novel robotic in-hand manipulation can execute grasping and cap manipulation by a single flexible shaft to simultaneously achieve bending and rotational movements. The relationship between stretching force and finger’s curvature can enable a custom design for user-specific applications.

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.

This paper introduces the modular design and manufacturing method, mechanical model, and test verification of a new type of soft actuator driven by fluid. First, the modular design scheme and driving principle of omnidirectional bending and elongation of the soft actuator are described. Three print-based elastic air cavities constrained by fire lines are distributed radially inside the actuator. The actuator can complete the 3 DOF motions of omnidirectional bending and elongation. From the basic principle of material mechanics, a novel mechanical model of the soft elastomer actuator is established. By numerically solving the nonlinear model, the relationship between actuator elongation/bending angle and driving pressure is obtained. The theoretical prediction and test results show that the deformation of the actuator exhibits a linear relationship with pressure when the chambers are charged. Additionally, the maximum allowable load force on the actuator terminal also exhibits good linearity when the driving pressure increases. Furthermore, the established mechanical model, which considers gravity effects can more accurately describe the features of bend and elongation of the actuator. The results shows that the proposed model is more convenient than the FEM models. This study provides theoretical support for accurate control of a soft actuator.

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.

The embodied theory of tooling predicts that when using a grasped object as a tool, individuals accommodate their actions to manage the altered degrees of freedom in the body-plus-object system. We tested predictions from this theory by studying how 3 tufted capuchin monkeys (Sapajus spp.) and 6 humans (Homo sapiens) used a hoe to retrieve a token. The hoe's handle was rigid, had 2 segments with 1 planar joint, or had 3 segments with 2 (orthogonal) planar joints. When jointed, rotating the handle could render it rigid. The monkeys used more actions to retrieve the token when the handle had 1 joint than when it had no joints or 2 joints. They did not use exploratory actions frequently nor in a directed manner in any condition. Although they sometimes rotated the handle of the hoe, they did not make it rigid. In a follow-up study, we explored whether humans would rotate the handle to use a 2-jointed hoe in a conventional manner, as predicted both by the embodied theory and theories of functional fixedness in humans. Two people rotated the handle to use the hoe conventionally, but 4 people did not; instead, they used the hoe as it was presented, as did the monkeys. These results confirm some predictions but also highlight shortcomings of the embodied theory with respect to specifying the consequences of adding multiple degrees of freedom. The study of species' perceptual sensitivity to jointed object's inertial properties could help to refine the embodied theory of tooling. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Inspired by flatworm locomotion, we proposed concept of a novel flatworm like robot named WORMESH. The feature of this robot is its structure, in which the component links are connected in a mesh pattern in the vertical and horizontal directions with joints having multiple degrees of freedom. The entire body of the robot is flexed to create multiple pedal waves simultaneously, to move and work. The second experimental model, WORMESH-II was then developed, with newly designed interlocking double joints. Further, its mobility performance is being verified.

Purpose To determine whether children and adults with unilateral congenital upper limb amputation can control myoelectric prostheses with multiple degrees of freedom (DOF) using pattern recognition (PR) technology. Methods Seven participants (age 9–62 years) with unilateral congenital transradial amputation were tested on both their residual and sound side limbs to determine proficiency in controlling a virtual prosthesis using electromyographic signals captured by an array of surface electrodes that were processed using PR technology. Proficiency was measured through a virtual environment game called the target achievement control test, in which the testing protocol asked participants to match increasingly complex prosthesis postures with 1, 2, and 3 DOF. Results All the participants successfully created a PR calibration at 1, 2, and 3 DOF with their residual limb during testing, and no differences in calibration accuracy were observed when comparing the residual versus sound upper limbs. No differences were noted in the mean completion rate on the target achievement control test between the residual and sound limbs. Conclusions Participants with a congenital upper limb amputation achieved PR control calibration of multi-DOF prostheses with proficiency and quality results of PR calibration that were comparable to those of their sound limb. This capability was observed in children as well as in adults. This demonstrates the potential for children and adults with a unilateral congenital transradial amputation to benefit from myoelectric prostheses with PR control. Clinical relevance The results from this study highlight the potential for patients in this population to benefit from myoelectric prostheses with PR control. Persons with unilateral congenital upper limb amputations can be considered for provision of this technology and enrollment in future research activities.

This paper wishes to present a compliant platform solution with multiple degrees of freedom, with the role of compensating vibrations and parasitic movements. In addition, there are key issues regarding the aspects of tremor, especially in the medical field. Of course, the emphasis is on the impact that tremor (vibrations) has in microsurgery, where very high positioning accuracies are required. Of interest, regarding the construction of the proposed platform, are the compliant elements that bring a series of advantages, starting from the simplification of the entire system and up to the manufacturing process of the platform, which is made monolithically by selective laser sintering (SLS) from PA2200 polyamide powder.

Inspection and maintenance of industrial pipes using robots represent an emerging application in Oil & Gas and refinery facilities for NonDestructive Tests (NDT). In this work, we present the design and development of a novel articulated mobile robot able to safely navigate over straight and curved pipes for inspection tasks. This rover is meant to be the base of the hybrid aerial-ground platform of the HYFLIERS project that aims to develop novel solutions to perform inspection measurements with reduced exposure to risks and costs. Thanks to the multiple degrees of freedom and onboard sensors, the rover proposed in this paper can stabilize and navigate on a pipe across welding and over curves. After discussed the mechanical design of the rover, we demonstrate its effectiveness in the localization and navigation of curved pipes.

Therapeutic endoscopic resection has gained favor for its ability to achieve high en bloc and histologically complete resection rates via a minimally invasive approach. The main technical difficulties faced by interventionists are first the lack of traction causing suboptimal visualization of the dis section field and second, the lack of triangulation using existing therapeutic apparatuses. These challenges can be overcome with the use of robots and the multiple degrees of freedom afforded by the robotic wrists. Nevertheless, com plications such as bleeding and perforation can occur. It is hence beneficial for the robotic device to be equipped with additional abilities such as suturing. Once the robotic proto types have been fully optimized and marketed, a structured program should be instituted to ensure proper and adequate training of the end-users. The future of robotics should then explore the possibility of developing a soft robot or a robot with more natural human-like movements. A robot with a force feedback mechanism would be superior and improve safety. Eventually, a supervised autonomous robot may per form interventions with greater precision and accuracy than an expert procedurist. This review describes the benefits of robot-assisted endoscopic resections, recent developments aimed at managing iatrogenic complications and future di rections for robotic endoscopy. (Gut Liver 2020;14:150-152)

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 describes economical strategies to design electrical substations and control buildings that are commonly used at industrial plants. Limited literature addressed design aspects for this class of buildings. Furthermore, little guidelines are available in practice to regulate this type of steel construction. The first part of the paper overviews the architectural and structural layouts of electrical buildings. Blast resistance requirements for occupied control buildings are also discussed. Simplified multiple degrees of freedom (MDOF) dynamic model is also illustrated that can be utilized for analysis of the blast resistant buildings. The economical aspects and cost savings resulting in using mobile industrial buildings are discussed. The article also highlights the engineering challenges that are encountered in design of mobile electrical facilities. The transportation procedure and design requirements are briefly described. Guidelines are proposed to calculate the center of mass of the building combined with interior equipments. The proposed design concept for electrical and control buildings is cost effective and can be implemented in industry to reduce projects cost.

The image quality of reflective optical systems is influenced strongly when the position of each mirror changed compared to the theoretical design state. Since multiple degrees of freedom in reflective optical system and the interaction between each mirror coupled, which makes it difficult to separate the misalignment of each mirror accurately. By now, vector wave-front aberration theory has been used to computer-aided alignment of two-mirror and three-mirror optical systems widely, however, due to actual engineering demands, optical systems with more than three mirrors have been designed, which greatly increases the difficulty of installation and alignment. At present, there are still few researches on this aspect. Based on vector wave aberration theory, the aberration shift vector of each element in four-mirror optical systems with off-axis field is derived by using paraxial ray trace equation of the optical axis ray and the principle ray, then the misalignment model of the four-mirror optical systems with shifted field is established in detail. The model can accurately calculate the misalignment of optical elements, which greatly promotes the high-precision alignment of complex reflective optical systems. And the perturbed off-axis four-mirror telescope can be perfectly aligned in terms of the vector aberration theory. This greatly facilitates the optical design technology of complex reflective optical systems in some way.

Vector beam with spin-orbital non-separable coupling acts as classically entangled state with two degrees of freedom, here we generalize the ray-wave structured vectorially structured light to create multi-degree-of-freedom control towards high-dimensional classical entanglement.

The basic approach of elastic actuation can be expanded to applications with multiple Degrees of Freedom (DoF). In this chapter, conceptual configurations and examples are described. Control approaches such as linear-quadratic-integral (LQI) and cascaded force-velocity control are presented and discussed, including the equivalence of these schemes for the 1-DoF case. In addition, underactuation and kinematic redundancy are considered with relation to robotic systems with elastic actuation.

Most of the structures represented as multiple degrees of freedom system are subjected to dynamic loads, for which they are to be analysed.

After getting a taste of two degrees of freedom system, we now proceed to a more general treatment of the problem. In the previous chapter, it is revealed that the two degrees of freedom system are more involved in computation than the single degree of freedom system. When more number of masses are considered, the mathematical formulation becomes much more complicated.

Many real-world applications, including adaptive radar scanning and smart stealth, require reconfigurable multifunctional devices to simultaneously manipulate multiple degrees of freedom of electromagnetic (EM) waves in an on-demand manner. Recently, kirigami technique, affording versatile and unconventional structural transformation, has been introduced to endow metamaterials with the capability of controlling EM waves in a reconfigurable manner. Here, we report for a kirigami-inspired sparse meta-architecture, with structural density of 1.5% in terms of the occupation space, for adaptive invisibility based on independent operations of frequency, bandwidth, and amplitude. Based on the general principle of dipolar management via structural reconstruction of kirigami-inspired meta-architectures, we demonstrate reconfigurable invisibility management with abundant EM functions and a wide tuning range using three enantiomers (A, B, and C) of different geometries characterized by the folding angle β . Our strategy circumvents issues of limited abilities, narrow tuning range, extreme condition, and high cost raised by available reconfigurable metamaterials, providing a new avenue toward multifunctional smart devices.

Certain nonlinear phenomena can occur only with systems having multiple degrees of freedom. Thus, nonlinear interaction requires the presence of at least two components that can interact. In this chapter we shall consider only 2-DOF systems, since these will suffice for illustrating important properties of nonlinear multiple-DOF systems in general. A 2-DOF model typically arises as an approximation to a real multiple-DOF or continuous system, for which a single-DOF model fails to describe the behavior to be studied.

It is known that coordination between joint movements is crucial for the achievement of motor tasks and has been studied extensively. Especially, in sports biomechanics, researchers are interested in determining which joint movements are coordinated to achieve a motor task. However, this issue cannot be easily addressed with the methods employed in previous studies. Therefore, we aimed to propose a method for identifying joint coordination. Subsequently, we examined which joint movements were coordinated using accurate overhead throwing, which required reduction in vertical hand velocity variability. Fourteen baseball players participated by attempting throwing using a motion capture system. The index of coordination for each joint movement and the effect of deviation of one joint movement on vertical hand velocity were quantified. Our results showed that the shoulder internal/external rotation angle (θ1-IE) and the other joint movements or the shoulder horizontal flexion/extension angular velocity (ω1-FE) and the other joint movements were coordinated. These results could be explained by the fact that the effects of the deviation of the shoulder internal rotation angle (θ1-I) and shoulder horizontal flexion angular velocity (ω1-F) on vertical hand velocity were larger than those of the other joint movements. This meant that it was necessary to cancel the deviations of θ1-IE and ω1-FE by the other joint movements. These findings indicate that the method proposed in this study enables the identification of which joint movements are coordinated in multiple degrees of freedom.

“Tsumori Control” is proposed as a control method to solve the problem of maneuvering, which requires multiple degrees of freedom. From previous studies, Tsumori Control has been able to estimate current behavioral intentions, but a delay always occurs. It is a problem for intuitively control the robot. Therefore, the purpose of this study is the possibility of estimating the behavior intention of one behavioral segment in the future with Tsumori Control. As a result, we present the possibility of estimating behavioral intention in the future with Tsumori Control.

This article presents a systematic method useful in the structural design and motion synthesis of motion assist exoskeleton. To this end, a method for analyzing complex human motions with multiple degrees of freedom for different functions and for regenerating arbitrary motions from the analyzed data by adjusting parameters based on the principal component analysis is described. An illustrative example on the design of walking assist device for hemiplegics is presented.

We observe the coupled dynamics of both translational motion and torsional vibration for a levitated nanodumbbell at high vacuum. We also report cooling multiple degrees of freedom of the levitated nanodumbbell.

Measurement-device-independent quantum key distribution (MDI-QKD) provides us a powerful approach to resist all attacks at detection side. Besides the unconditional security, people also seek for high key generation rate, but MDI-QKD has relatively low key generation rate. In this paper, we provide an efficient approach to increase the key generation rate of MDI-QKD by adopting multiple degrees of freedom (DOFs) of single photons to generate keys. Compared with other high-dimension MDI-QKD protocols encoding in one DOF, our protocol is more flexible, for our protocol generating keys in independent subsystems and the detection failure or error in a DOF not affecting the information encoding in other DOFs. Based on above features, our MDI-QKD protocol may have potential application in future quantum communication field., Comment: 10 pages, 3 figures, accepted in Front. Phys

A multi-degree of freedom (MDOF) system describes structural motion with multiple degrees of freedom.

StartReact is the ability of the startle reflex to involuntarily release a planned movement in the presence of a loud acoustic stimulus resulting in muscle activity patterns and kinematics that are tightly regulated and scaled with the intended action. Previous studies demonstrated startReact's robustness during simple single-joint reaching tasks and found no difference between startReact and voluntary movements for movement kinematics and muscle activation patterns. However, startReact has not been evaluated during multi-joint reaching movements with multiple degrees of freedom. It is unclear if startReact would evoke accurate and precise multi-joint reaching movements in an unrestricted workspace. Furthermore, if tested more rigorously, multi-joint startReact movement kinematics and muscle activation patterns might not be truly equivalent despite showing no difference through traditional ANOVAs. A previous study found multi-joint startReact was possible during unrestricted elbow and shoulder movement when reaching to a forward target. Therefore, we hypothesized that startReact would evoke similar multi-joint reaching movements for movement accuracy and muscle activation patterns when compared to voluntary movements in a multi-directional workspace. Expanding upon the previous study, our study uses a larger workspace and fully evaluates movement kinematics and muscle activations patterns. Results confirmed our hypothesis and found startReact movements were readily evoked in all directions. StartReact responses presented stereotypically earlier muscle activation, but the relative timing of agonist/antagonist firing pairs between startReact and voluntary movements remained similar. Results demonstrate that startReact is robustly present and equivalent in multi-joint reaching tasks and has potential clinical use for evaluating healthy and impaired movement.

Objectives The aim of the present study was to examine whether movement contingent sensory effects could be used to prime and facilitate motor performance on a ball-tossing task. Design The ball-tossing task was performed across two consecutive days, and consisted of an acquisition phase and a test phase. During the acquisition phase, participants ( N = 30) practiced an underhanded ball tossing task to a near and far target ( N = 360 total, n = 180 each distance). Tosses that landed near the target immediately produced an auditory feedback tone upon landing, with unique tones for both the near and far target. In the test phase, the auditory tones preceded the toss and served as imperative stimuli for the tossing task. Method The test phase consisted of three tossing conditions (corresponding, non-corresponding, and control) in which the participants responded to the tones by tossing the ball to either the corresponding or non-corresponding target associated with the tones during learning. Results Findings indicated that both accuracy and consistency of ball tossing improved when the toss was preceded by the corresponding auditory feedback associated with the successful execution of the action during learning. Conclusions The present study extends previous research by showing that complex actions consisting of multiple degrees of freedom can be primed via movement contingent sensory effects. Furthermore, this study demonstrates that movement-effect priming can impact distal measures of motor performance (e.g., accuracy of tossing), as opposed to the features of movement production (e.g., response selection, initiation, and execution).

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.

Vibration vehicle models provide a great opportunity to integrate vehicle-based vibrations into a mechanical engineering vibrations course. This paper documents and discusses an approach to a multiple-degree-of-freedom (MDOF) in regards to pitch and bounce of the vehicle body with dampening and stiffness observed. The approach utilizes hand calculations, OCTAVE, and ANSYS to solve speed-bump induced vibration and to calculate vibrations modes. The problem involves a bicycle-model approach to a vehicle’s response when subject to a speed bump, or a sudden impulse load upon the forward-face of the model. These responses are captured and analyzed on pitch and bounce of the model at the center-of-gravity and the front/rear sides of the model. Graphical models capture responses of the loading conditions and the modal equations of the model providing a method of studying and understanding vibrational responses under provided stiffness. Using ANSYS as an approach of the model to capture damping response, further graphical models can be captured and used to describe motions of the vehicle model’s center-of-gravity, frontward and rearward wheel assembly, and the pitch (rotation) of the center-of-gravity to the introduced responses. A successful study with analysis of each graphical element and further dissemination of the results is concluded.

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.

Humans perform a variety of feedback adjustments to maintain balance during walking. These include lateral footfall placement, and center of pressure adjustment under the stance foot, to stabilize lateral balance. A less appreciated possibility would be to steer for balance like a bicycle, whose front wheel may be turned toward the direction of a lean to capture the center of mass. Humans could potentially combine steering with other strategies to distribute balance adjustments across multiple degrees of freedom. We tested whether human balance can theoretically benefit from steering, and experimentally tested for evidence of steering for balance. We first developed a simple dynamic walking model, which shows that bipedal walking may indeed be stabilized through steering—externally rotating the foot about vertical toward the direction of lateral lean for each footfall—governed by linear feedback control. Moreover, least effort (mean-square control torque) is required if steering is combined with lateral foot placement. If humans use such control, footfall variability should show a statistical coupling between external rotation with lateral placement. We therefore examined the spontaneous fluctuations of hundreds of strides of normal overground walking in healthy adults (N = 26). We found significant coupling (P = 9·10−8), of 0.54 rad of external rotation per meter of lateral foot deviation. Successive footfalls showed a weaker, negative correlation with each other, similar to how a bicycle’s steering adjustment made for balance must be followed by gradual corrections to resume the original travel direction. Steering may be one of multiple strategies to stabilize balance during walking.

Restoration of intestinal continuity following total proctocolectomy is performed by constructing an ileal pouch-anal anastomosis (IPAA). Since the advent of this technique in 1978, the operation has evolved from hand-sewn to stapled anastomoses, from a two-stage to three-stage approach in the setting of immunosuppression, and from an open technique to a minimally invasive approach. While laparoscopy has become widely used for IPAA construction, a robotic approach may offer several advantages and may become more widely used in future years. The bony confines of a narrow pelvis make the angles of laparoscopy challenging, and the robot provides improved three-dimensional and high-definition visualization of the pelvis. Once the pelvic floor has been exposed, the improved visualization and multiple degrees of freedom help to improve deployment of intracorporeal stapling devices. Herein, we discuss our approach to a robotic IPAA and highlight steps that may require intraoperative troubleshooting.

Prosthetics need to incorporate the users sense of proprioception into the control paradigm to provide intuitive control, and reduce training times and prosthetic rejection rates. In the absence of functional tasks with a prosthetic, virtual cursor control tasks have been used to train users to control multiple degrees of freedom. In this study, A proportional position signal was derived from the cross-sectional ultrasound images of the users forearm. We designed a virtual cursor control task with one degree of freedom to measure the users ability to repeatably and accurately acquire different levels of muscle flexion, using only their sense of proprioception. The experiment involved a target acquisition task, where the cursors height corresponded to the extent of muscle flexion. Users were asked to acquire targets on a screen. Visual feedback was disabled at certain times during the experiment, to isolate the effect of proprioception. We found that as visual feedback was taken away from the subjects, position error increased but their stability error did not change significantly. This indicates that users are not perfect at using only their proprioceptive sense to reacquire a level of muscle flexion, in the absence of haptic or visual feedback. However, they are adept at retaining an acquired flexion level without drifting. These results could help to quantify the role of proprioception in target acquisition tasks, in the absence of haptic or visual feedback.

Stimulus distribution on a finger pad dynamically changes during dynamic interactions such as manipulation or handling of an object. This is caused by the magnitude and direction of the applied force on the finger pad and the elasticity of materials handled. Several past studies proposed wearable tactile systems. However, generation of distributed stimuli on a finger pad (multiple degrees of freedom stimulation) has not yet been achieved. Herein, we propose a rendering system for stimulus distribution on a finger pad. The proposed system consists of a display using multi-channel suction that presents distributed stimuli to a finger pad skin, and a real-time simulator that calculates dynamic pressure distribution on the finger pad when in contact with an elastic object. The developed display has good wearability as lightweight (5 g) and compact because it does not have an actuator on the fingertip in spite of multiple outputs (16 suction ports). We performed two different experiments using the proposed system. These experiments proved that it is possible to present different stimulus distribution depending on the contact posture between a finger and an object (experiment 1) and to present the softness of the virtual material with different elasticity values (experiment 2).

To reduce the torsional vibration of vehicle power transmission system (VPTS), a torsional vibration model with multiple degrees of freedom (MDOF) of VPTS was established. The scheme of equipping torsional vibration dampers (TVDs) on the drive shaft was employed by the calculation of the forced vibration and the free vibration of the VPTS. The energy method was used to optimize the parameters of single-stage, two-stage parallel, and two-stage series TVDs based on the principle that balances the damping effect and lightweight design. On the basis of this, the parameters of the models incorporating TVD and elastic couplings (ECs) were optimized. Results showed that the proposed method can ensure the damping effects of TVD and realize the lightweight.