Tail Swing Research Articles

Stability and Controller Research of Double-Wing FMAV System Based on Controllable Tail.

This study aimed to enhance the stability and response speed of a passive stabilized double-wing flapping micro air vehicle (FMAV) by implementing a feedback-controlled biomimetic tail. A model for flapping wings accurately calculated the lift force with only a 2.4% error compared to the experimental data. Experimental tests established the relationship between control torque and tail area, swing angle, and wing-tail spacing. A stability model for the double-wing FMAV was developed, incorporating stabilizing sails. Linearization of the hovering state facilitated the design of a simulation controller to improve response speed. By adjusting the feedback loops of velocity, angle, and angular velocity, the tail controller reduced the angle simulation response time from 4 s to 0.1 s and the velocity response time from 5.64 s to 0.1 s. In take-off experiments, a passive stabilized prototype with an adjustable tail angle exhibited enhanced flight stability compared to fixed tails, reducing standard deviation by 72.96% at a 0° take-off angle and 56.85% at a 5° take-off angle. The control axis standard deviation decreased by 38.06% compared to the passive stability axis, confirming the effectiveness of the designed tail angle controller in reducing angular deflection and improving flight stability.

Comparative study on lateral vibration characteristics of the head and tail cars of high-speed trains under unsteady aerodynamic loadings

With the increasing speed of high-speed trains, abnormal vibrations in the tail car pose a threat to its overall stability and running safety. In this study, the aerodynamic and multibody dynamics models for 3-car and 8-car trains are established. The flow field characteristics and dynamic performance around the head and tail cars under both steady and unsteady aerodynamic loadings at a speed of 400 km/h are compared. The results reveal that the surrounding flow field exhibits highly pronounced unsteady characteristics, directly leading to a significant impact of unsteady aerodynamic loadings on the train's dynamic response. Under unsteady loadings, the lateral stability indexes, displacement, velocity, and acceleration of the tail car are all worser compared to those of the head car. Additionally, the larger oscillation amplitudes and frequencies closer to the suspension modal frequencies under unsteady aerodynamic loadings contribute to more pronounced lateral displacements and accelerations, constituting a crucial factor in the observed ‘tail swing' phenomenon for the high-speed train.

Spinetoram-Induced Potential Neurotoxicity through Autophagy Mediated by Mitochondrial Damage.

Spinetoram is an important semi-synthetic insecticide extensively applied in agriculture. It is neurotoxic to insects, primarily by acting on acetylcholine receptors (nAChRs). However, few studies have examined the neurotoxicity of spinetoram in human beings. In this study, various concentrations (5, 10, 15, and 20 μM) of spinetoram were employed to expose SH-SY5Y cells in order to study the neurotoxic effects of spinetoram. The results showed that spinetoram exposure markedly inhibited cell viability and induced oxidative stress. It also induced mitochondrial membrane potential collapse (ΔΨm), and then caused a massive opening of the mitochondrial permeability transition pore (mPTP), a decrease in ATP synthesis, and Ca2+ overloading. Furthermore, spinetoram exposure induced cellular autophagy, as evidenced by the formation of autophagosomes, the conversion of LC3-I into LC3-II, down-regulation of p62, and up-regulation of beclin-1. In addition, we observed that p-mTOR expression decreased, while p-AMPK expression increased when exposed to spinetoram, indicating spinetoram triggered AMPK/mTOR-mediated autophagy. Complementarily, the effect of spinetoram on neurobehavior was studied using the zebrafish model. After being exposed to different concentrations (5, 10, and 20 μg/mL) of spinetoram, zebrafish showed neurobehavioral irregularities, such as reduced frequency of tail swings and spontaneous movements. Similarly, autophagy was also observed in zebrafish. In conclusion, spinetoram exposure produced potential neurotoxicity through autophagy mediated by mitochondrial damage. The experimental data and results of the neurotoxicity study of spinetoram provided above are intended to serve as reference for its safety assessment.

Study on Lateral Vibration of Tail Coach for High-Speed Train under Unsteady Aerodynamic Loads

As the speed of high-speed trains increases, the vehicle’s lateral stability steadily deteriorates. There have been observations of abnormal vibrations in the tail car, particularly on certain sections of the railway line. This study built a high-speed train aerodynamic simulation model for a three-car consist, and a multibody dynamics simulation model for an eight-car consist based on numerical simulations of train aerodynamics and multibody dynamics. It investigated both steady and unsteady aerodynamic loads, flow field characteristics, and the dynamic performance of vehicles under varied aerodynamic loads at 400 km/h. The results indicate that the aerodynamic loads generated during high-speed train operation exhibit highly unsteady characteristics. Steady aerodynamic loads have a relatively minor impact on the vehicle’s dynamic performance, whereas unsteady loads exert a more significant influence. Under unsteady aerodynamic forces, the tail car experiences severe lateral vibrations. The lateral stability index, displacement, velocity, and acceleration of the tail car under unsteady conditions were measured at 2.26, 7.54 mm, and 0.53 m/s2, respectively. These values represent increases of over 17.71%, 148.84%, and 111.24%, respectively, compared to the steady loads. Large oscillation amplitudes result in more significant lateral displacements and accelerations of the vehicle. This phenomenon is a crucial factor contributing to the “tail swing” effect observed in high-speed trains. This study emphasizes the importance of considering unsteady aerodynamic effects in assessing the lateral stability of high-speed trains and highlights the significance of mitigating the adverse impacts of such dynamic responses, particularly in the tail car.

Tunable Tail Swing of Nanomillipedes.

The physical properties of graphene nanoribbons (GNRs) are closely related to their morphology; meanwhile GNRs can easily slide on surfaces (e.g., superlubricity), which may largely affect the configuration and hence the properties. However, the morphological evolution of GNRs during sliding remain elusive. We explore the intriguing tail swing behavior of GNRs under various sliding configurations on Au substrate. Two distinct modes of tail swing emerge, characterized by regular and irregular swings, depending on the GNR width and initial position relative to the substrate. The mechanism can be explained by the moiré effect, presenting both symmetric and asymmetric patterns, resembling a mesmerizing nanomillipede. We reveal a compelling correlation between the tail swing mode and the edge wrinkle patterns of GNRs induced by the moiré effect. These findings provide fundamental understanding of how edge effects influence the tribomorphological responses of GNRs, offering valuable insights for precise manipulation and operation of GNRs.

Effects of 0.4 T, 3.0 T and 9.4 T static magnetic fields on development, behaviour and immune response in zebrafish (Danio rerio)

Magnetic Resonance Imaging (MRI) is widely applied in medical diagnosis due to its excellent non-invasiveness. With the increasing intensity of static magnetic field (SMF), the safety assessment of MRI has been ongoing. In this study, zebrafish larvae were exposed to SMFs of 0.4, 3.0, and 9.4 T for 2 h (h), and we found that there was no significant difference in the number of spontaneous tail swings, heart rate, and body length of zebrafish larvae in the treatment groups. The expression of development-related genes shha, pygo1, mylz3 and runx2b in the three SMF groups was almost not significantly different from the control group. Behavior tests unveiled a notable reduction in both the average speed and duration of high-speed movements in zebrafish larvae across all three SMF groups. In addition, the 0.4 and 3.0 T SMFs increased the migration of neutrophils in caudal fin injury, and the expression of pro-inflammatory cytokines was also increased. To explore the mechanism of SMFs on zebrafish immune function, this study utilized aanat2−/− mutant fish to demonstrate the effect of melatonin (MT) involvement in SMFs on zebrafish immune function. This study provides experimental data for understanding the effects of SMFs on organisms, and also provides a new insight for exploring the relationship between magnetic fields and immune function.

A free-swimming tadpole model based on immersed boundary-lattice Boltzmann method and its application

A two-dimensional (2D) free-swimming tadpole model is built in this study using the immersed boundary-lattice Boltzmann method. The tadpole is developed by connecting a passive elliptical head with a beating tail. This developed tadpole is capable of controlling the tail swing amplitude to change the swimming speed and achieve the desired swimming direction by attaching an angle offset on the tail axis. The hydrodynamics of the proposed tadpole model in swimming is investigated by regulating the width of the confined space. To be specific, three points are summarized below. First, a lower swimming speed will be produced in a narrower channel under the identical swimming pattern. Second, under the effect of a slight swing strength, a small-scale disturbance is triggered to the surrounding fluid, and a small swimming speed will be generated. Third, a relatively small or excessive swimming speed adversely affects the stability of its swimming. Moreover, a perception-response strategy for the tadpole is further formulated to achieve its autonomous locomotion control. A virtual perceptive field is proposed as the visual range, which is conducive to implementing tadpole motion control based on a set of mechanical response rules. With the above-mentioned improvements, the tadpole can effectively achieve obstacle avoidance in sophisticated obstacle array environments and tracking sine curve routines. Accordingly, this study can provide a valuable reference for the theoretical design of underwater bionic tadpole-like robots.

Structure design and dynamic analysis of a tensegrity-based carangiform robotic fish

<p indent="0mm">Bionic robots are widely used in various fields due to their high flexibility and mobility. When conducting complex underwater operations, it is expected to design a bionic robotic fish with good underwater navigation ability based on the excellent swimming performance of fish. At present, the tail swing mechanism of bionic robotic fish is mostly composed of serial rigid joints. Limited by their own materials and manufacturing process, the joints cannot undergo large elastic deformation, so the corresponding bionic robotic fish is far less flexible than fish in water. A flexible design is a natural choice to better mimic the movement of fish underwater. Tensegrity is a grid-like spatial structural system that consists of pre-tensioned strings and pre-compressed bars. Such structure has the advantages of light weight, flexible deformation, and impact resistance. Introducing tensegrity into the robot field has greater advantages than traditional rigid robots due to its flexibility and other characteristics. Based on a novel 2D tensegrity and the physiological characteristics of fish, this paper proposed a four-joint bionic robotic fish that imitates carangiform swimming motions. Referring to the shape characteristics of fish, the three-dimensional model of robotic fish is established using software. By simplifying several ropes as the external forces of the system, ignoring the parameters of gravity, buoyancy and mass of some parts, the dynamic equations of the two-joint model are established through the coordinate transformation matrix and further extended to the multi-joint system. Taking the single and four-joint systems as examples, the accuracy of the dynamic model is verified by Adams simulations, and the obtained results are consistent with the motion curve of fish during cruise. In order to improve the propulsion performance of robotic fish, some parameters of the system are analyzed. When the stiffness distribution between the joints is changed, the results show that reducing the spring stiffness of the tail fin joint can effectively reduce the influence on the front-end joint. Further analysis is carried out on reducing the stiffnesses of only side springs, or both side and center springs. It is found that reducing the stiffnesses of only side springs is more conducive to the improvement of the driving effect. The influence of the driving strategy on the dynamic performance of the system is discussed, and the application of step function and sinusoidal function to the robotic fish without/with damping is also analyzed. The results show that the fluctuation of the sinusoidal function driven system is larger under the condition of without damping, and the similar dynamic response can be obtained under the condition of damping. This work provides a theoretical basis and application reference for the design of flexible robotic fish. The proposed tensegrity-based carangiform robotic fish holds potential applications as exploration, search and rescue equipment in complex underwater environments.

Design of Transverse Brachiation Robot and Motion Control System for Locomotion between Ledges at Different Elevations.

Bio-inspired transverse brachiation robots mimic the movement of human climbers as they traverse along ledges on a vertical wall. The constraints on the locomotion of these robots differ considerably from those of conventional brachiation robots due primarily to the need for robust hand-eye coordination. This paper describes the development of a motion control strategy for a brachiation robot navigating between wall ledges positioned on a level plane or at different elevations. We based our robot on a four-link arm-body-tail system performing a four-phase movement, including a release phase, body reversal phase, swing-up phase, and grasping phase. We designed a gripper that uses passive wrist joint motion to grasp the ledge during the tail swing. We also developed a dynamic model by which to coordinate the swing-up movement, define the phase switching conditions, and time the grasping action of the grippers. In experiments, the robot proved highly effective in traversing between wall ledges of the same or different elevations.

A Novel Fish-Inspired Robot with a Double-Cam Mechanism

Fishes have evolved different excellent swimming strategies. To study the influence of tail fin swing on the swimming performance of bionic robot fish, with one joint under the same tail swing frequency and amplitude, we designed a novel robot fish, driven by a double-cam mechanism. By designing the profile of the cam in the mechanism, the robot fish can achieve different undulatory motion trajectory of the caudal fin under the same tail swing frequency and amplitude. The mechanism simulated the undulatory motion of crucian carp. We studied the influence of undulatory motion on the swimming speed of robot fish, which was analyzed by dynamic analysis of the undulatory motion and experiments. According to the experimental results, we can find that the swimming speed of the robotic fish is different under various wave motions. When other conditions are the same, the speed that the robot fish can achieve by imitating the swing motion of the real fish is 1.5 times that of the robot fish doing the cycloid motion. The experimental results correspond to the kinetic analysis results. Furthermore, it is proven that the robot fish with a low caudal peduncle stiffness swims faster under a low swinging frequency, and the speed of a robot fish with a high caudal peduncle stiffness is higher under a high tail swinging frequency.

Development of a Bionic Dolphin Flexible Tail Experimental Device Driven by a Steering Gear

In order to study the mechanism of the tail swing of the bionic dolphin, a flexible tail experimental device based on a steering engine was developed. This study was focused on the common three joint steering gear and its use in a bionic dolphin tail swing mechanism, and it was found that the bionic dolphin driven by the steering gear had the problem of excessive stiffness. In order to solve this problem, we designed a bionic dolphin tail swing mechanism. The tail swing mechanism was designed rationally through the combination of a steering gear drive and two flexible spines. Analysis of kinematic and dynamic modeling was further completed. Through simulation using, the research on the bionic dolphin tail swing mechanism was verified. Experiments showed that the swing curve formed by the steering gear-driven bionic dolphin tail swing mechanism with two flexible spines fit the real fish body wave curve better than the original bionic dolphin tail swing mechanism.

The Opportunities and Challenges Overview: Implementing Performance Based Standards Regulation for High Capacity Passenger Vehicle in Malaysia

&#x0D; &#x0D; &#x0D; Road accidents involving heavy commercial passenger vehicle (HCPV) in Malaysia have always been in the spotlight and various efforts have been taken with much attention given on operational issues. At present, the weight and dimensions of HCPV in Malaysia generally regulated under prescriptive standards regulations which do not provide clear safety outcomes and often limits the flexibility about how to achieve it. This paper provides an overview of opportunities and challenges of implementing Performance Based Standards (PBS) regulation for HCPV vehicle in Malaysia based on the Australian PBS regulation implementation for heavy vehicle. It was found that Tail Swing, Braking Efficiency and Maximum Stable Inclination Angle under the existing regulation have or partly met the PBS approach. The opportunities for implementing PBS regulation were explained in terms of the possibility adopting PBS approaches in the existing regulation and second, the institutional readiness to develop and implement it. However, challenges were expected, for example increase in cost of vehicle’s assessment. Implementing PBS regulation for HCPV in Malaysia will provide various benefits such as increase productivity, efficiency and most importantly safety.&#x0D; &#x0D; &#x0D;

Modeling and simulation of the intermittent swimming gait with the muscle-contraction model of pre-strains

The muscle-contraction model of pre-strains is employed to study the intermittent swimming gait of a 2D freely swimming fish. The fluid-structure interaction problem of fish swimming is solved with the finite elements method. Benefits of the intermittent swimming and the effects of the duty cycle and the tail swing number in a burst phase are emphasized. The results show that, compared to the steady swimming, a huge energy saving for swimming can be achieved by sacrificing a little speed during the intermittent swimming. Moreover, the fish swimming can be gradually transited from an intermittent mode to the continuous mode by increasing the duty cycle. With a smaller duty cycle, the fish can save more energy to obtain the same swimming velocity. A smaller tail swing number in a burst phase is more helpful to improve the energy utilization rate under the condition of Rduty = 0.5. In addition, the intermittent swimming will have more benefits at the lower and the higher average swimming speeds, and it is very important to have a proper proportion of the velocity bounds for the performance improvement of the intermittent swimming. These conclusions may have direct meanings for the development of biomimetic autonomous underwater vehicles.

Mammals repel mosquitoes with their tails.

The swinging of a mammal's tail has long been thought to deter biting insects, which, in cows, can drain up to 0.3 liters of blood per day. How effective is a mammal's tail at repelling insects? In this combined experimental and theoretical study, we filmed horses, zebras, elephants, giraffes and dogs swinging their tails. The tail swings at triple the frequency of a gravity-driven pendulum, and requires 27 times more power input. Tails can also be used like a whip to directly strike at insects. This whip-like effect requires substantial torques from the base of the tail on the order of 101-102Nm, comparable to the torque of a sedan, but still within the physical limits of the mammal. Based on our findings, we designed and built a mammal tail simulator to simulate the swinging of the tail. The simulator generates mild breezes of 1 m s-1, comparable to a mosquito's flight speed, and sufficient to deter up to 50% of mosquitoes from landing. This study may help us determine new mosquito-repelling strategies that do not depend on chemicals.

Active Trailer Steering Control for High-Capacity Vehicle Combinations

In this paper, a new control strategy for the active steering of a trailers of longer and heavier vehicle combinations is proposed to improve both low speed maneuverability and high speed stability. A novelty of the approach is in the use of a single controller structure for all velocities using a gain scheduling method for optimal performance at any velocity. To achieve such a control objective, the problem is initially formulated as a path following problem and subsequently transformed into a tracking problem using a reference model. To support controller design, a generic nonlinear model of a double articulated vehicle, based on a single track model, is employed. The proposed systematic design approach allows to easily adjust the controller for additional trailers or different dimensions, in which only some of the towed vehicles are allowed to steer. The performance of the controller is verified on a high-fidelity multi-body model for evidencing the practical applicability of the approach. Simulation results show substantial reduction of both, the swept path width and tail swing for low speed, and the rearward amplification for high speed.

鱼体文字意涵及其艺术赏析

书法所赋予文字艺术之创作，随历代闻人创作而有不同的风貌与价值。现代人若仅继承或充实传统书法艺术，则文字艺术将走入死胡同。勇于以各种造型观念去诠释文字之特性和书法艺术之内涵，将可活化文字艺术创作并增其光辉。是以吾人利用鱼体来取代生硬的字体笔划而让字体充满灵性与生命，于是乎创出了鱼体文字。鱼体文字是以鱼体为建构基素，而鱼种类有千、万种，其悠游姿态亦多不胜数，而其色彩更是缤纷绚丽；若吾人将其组合成字体，将可见到变幻万端之字体及所呈现之美感，例如象形之美、书画之美、气韵之美、创意之美、祥和之美及灵动之美。另外，鱼儿生命循环、悠游姿态(或跃、或潜、或摆)皆有其意涵，在感受自然生命之流转后而赋予鱼体文字特有之意涵。端此，鱼体文字将牵涉到：字的艺术、字意艺术、色彩艺术、外体形状艺术、整体结构艺术及动态艺术等，此等将可满足作者在书写上的万般巧思。 Calligraphy’s creation for word of art has different styles and values under the creation of celebrity in past dynasties. If the modern people only inherit or enrich the traditional art of calligraphy, then the word art will go into a dead end. Using variety of modeling ideas bravely to interpret the characteristics of the word and the connotation of calligraphy art will be able to activate the word art creation and increase its glory. Thus we use fish script to replace the blunt font such that the font will be full of spirituality and life. And then the word with fish script is created. This word is constructed based on the body format of the fish and while they come in thousand types of different species so are the chorographical swimming movements as well as the abundance of radiant colors they come with, and that being said, one can only imagine the result of the combination is unspeakably beautiful and radiant. If we combine it into a word, one can see the fantasy of the word and its beauty shown, such as the beauty of pictographic, the beauty of painting and calligraphy, the beauty of artistic conception, the beauty of creation, the beauty of peace and the beauty of agility. Furthermore, the fish’s life cycle and leisurely attitude (body jump, dive and tail swing) have their unique meaning. That is we will give special meaning to word with fish script after feeling the flow of natural life. Therefore, the art of word with fish script will include art of word, art of literal meaning, art of color, art of structure shape, art of structure in whole word and kinetic art and etc. And that will be able to meet the author's writing on the ingenuity.

Trailer Steering Control of a Tractor–Trailer Robot

In this paper, we consider active trailer steering control as a means to improve the maneuverability of (long) truck–trailer combinations during cornering. Hereto, we formulate the problem of reducing the so-called swept path width during cornering and that of eliminating unsafe tail swing of the trailer as a tracking control problem. We present a kinematic tractor–trailer model including off-axle hitching, on the basis of which we design nonlinear control strategies solving this tracking problem. The effectiveness of the proposed approach is evidenced experimentally on a robotic tractor–trailer platform.

The coordination of cyclic microtubule association/dissociation and tail swing of cytoplasmic dynein

The dynein motor domain is composed of a tail, head, and stalk and is thought to generate a force to microtubules by swinging the tail against the head during its ATPase cycle. For this "power stroke," dynein has to coordinate the tail swing with microtubule association/dissociation at the tip of the stalk. Although a detailed picture of the former process is emerging, the latter process remains to be elucidated. By using the single-headed recombinant motor domain of Dictyostelium cytoplasmic dynein, we address the questions of how the interaction of the motor domain with a microtubule is modulated by ATPase steps, how the two mechanical cycles (the microtubule association/dissociation and tail swing) are coordinated, and which ATPase site among the multiple sites in the motor domain regulates the coordination. Based on steady-state and pre-steady-state measurements, we demonstrate that the two mechanical cycles proceed synchronously at most of the intermediate states in the ATPase cycle: the motor domain in the poststroke state binds strongly to the microtubule with a K(d) of approximately 0.2 microM, whereas most of the motor domains in the prestroke state bind weakly to the microtubule with a K(d) of >10 microM. However, our results suggest that the timings of the microtubule affinity change and tail swing are staggered at the recovery stroke step in which the tail swings from the poststroke to the prestroke position. The ATPase site in the AAA1 module of the motor domain was found to be responsible for the coordination of these two mechanical processes.

Kinetic Characterization of Tail Swing Steps in the ATPase Cycle of Dictyostelium Cytoplasmic Dynein

According to the power stroke model of dynein deduced from electron microscopic and fluorescence resonance energy transfer studies, the power stroke and the recovery stroke are expected to take place at the two isomerization steps of the ATPase cycle at the primary ATPase site. Here, we have conducted presteady-state kinetic analyses of these two isomerization steps with the single-headed motor domain of Dictyostelium cytoplasmic dynein by employing fluorescence resonance energy transfer to probe ATPase steps at the primary site and tail positions. Our results show that the recovery stroke at the first isomerization step proceeds quickly ( approximately 180 s(-1)), whereas the power stroke at the second isomerization step is very slow ( approximately 0.2 s(-1)) in the absence of microtubules, and that the presence of microtubules accelerates the second but not the first step. Moreover, a comparison of the microtubule-induced acceleration of the power stroke step and that of steady-state ATP hydrolysis implies the intriguing possibility that microtubules simultaneously accelerate the ATPase activity not only at the primary site but also at other site(s) in the motor domain.

3P144 細胞質ダイニンの微小管相互作用と尾部スイングの協調(分子モーター,ポスター発表,第45回日本生物物理学会年会)

3P144 細胞質ダイニンの微小管相互作用と尾部スイングの協調(分子モーター,ポスター発表,第45回日本生物物理学会年会)