Leg Structure Research Articles

Structural design and gait research of a new bionic quadruped robot

Quadruped bionic robot has a strong adaptability to the environment, compared with wheeled and tracked robots, it has superior motion performance, and has a wide range of application prospects in rescue and disaster relief, ground mine clearance, mountain transportation, so it has become a research hotspot all over the world. Leg structure is an important embodiment of the superior performance of quadruped robot, and it is also the key and difficult point of design. This article proposes a novel quadruped robot with waist structure, which can complete a variety of gait forms. Based on the theory of linkage mechanism, a novel leg structure is designed with anti-parallelogram mechanism, which improves the strength and stiffness of the robot. Using D-H description method, the kinematics analysis of this quadruped robot single leg is carried out. On this basis, in order to ensure the foot contact with the ground and achieve zero impact, polynomial programming is used to plan the foot trajectory of swing phase and support phase. Based on the static stability margin, the optimal static gait of the quadruped robot is planned. A co-simulation study has been carried out to investigate further the validity and effectiveness of the quadruped robot on gait. The simulation results clearly show the robot can walk steadily and its input and output meet the expected requirements. The solid prototype platform is built, and the trajectory planning experiment of single leg is carried out, and the foot trajectory of single leg is obtained by using laser tracker. The gait planning algorithm is applied to the whole robot, and the results show that the robot can walk according to the scheduled gait, which proves the effectiveness of the proposed algorithm.

Two new species of the bee-mimicking genus Mallophora (Diptera, Asilidae) from Colombia.

Mallophora Macquart, 1834 is a bee-mimicking genus of Asilidae, which has more than 50 described species in the Neotropical Region. Examination of specimens of this genus from Colombia indicate that there are two undescribed species based on the structure of the hind leg of males. Here we describe Mallophora gauteovan sp. nov. and Mallophora kalos sp. nov. from Tayrona National Park (Magdalena) and Arauca, respectively. For each new species a diagnosis and a description including the structure of the face, thorax, male hind leg, abdomen, and hypandrium are provided. All morphological structures are documented with digital photographs.

Conceptual Design of the Combinable Legged Robot Bio-Inspired by Ants’ Structure

This study presents a new combinable multi-legged modular robot that mimics the structures of ants to expand the physical capabilities of the legged robot. To do this, the robot design is focused on exploring a fusion of two robotic platforms, modular and multi-legged, in which both the body frame and the legged structure are designed to be a rectangular prism and a 3-DoF sprawling-type articulated leg structure, respectively. By imitating ants’ claws, the hook-link structure of the robot as the coupling mechanism is proposed. This study includes the platform’s development, and the experimental work on the locomotion in both single and combined modes is carried out. The result of this study proves that mimicking ants’ structure in the proposed robots successfully enhances the capability of the conventional legged robot. It is feasible to use in a multi-robot system to realize ants’ super-organized behavior.

Research on fuzzy control of permanent magnet synchronous motor for a mobile robot

In this paper, a biped robot powered by permanent magnet synchronous motor (PMSM) is proposed, and each leg of the robot is a 6-degrees of freedom (DOF) parallel mechanism. Due to highly nonlinear characteristics of the leg structure, the conventional PID control strategy based on trial-error process cannot maintain the high performance of the PMSM. In order to improve the robustness of PMSM servo system and the dynamic stability of the robot, the PID controller based on fuzzy theory is developed. Fuzzy PID controller can improve the tracking accuracy and load rejection capability of PMSM, which makes the real-time system response faster without overshoot. The simulation results show that compared with conventional PID, fuzzy PID can reduce position tracking error of PMSM and deal with the external disturbance effectively.

Do holometabolous insects molt spontaneously after adulthood? An exceptional case report in fireflies (Coleoptera: Lampyridae), with discussion of its inferred endocrine regulation especially in relation to neoteny

It has been a traditionally held view that winged insects stop molting after they reach adulthood. We observed a fascinating phenomenon of a post-imago molt occurring in the neotenic females of a firefly species in Taiwan over the last two years. By rearing Lamprigera minor larvae to adults, four out of the five unmated females studied were found undergoing an extra molt 8–18 days after adult eclosion. They were reproductively mature when the post-imago molt occurred, as evidenced by the eggs inside their bodies. The four females died without oviposition whereas the only normal female laid eggs. A comparison of exuviae of different stages confirmed the existence of post-imago ecdysis. The adult skin differed from the pupal one mainly in the mouthparts and leg structures. No mix of pupal and adult traits was seen in the adult skin. The females retained the same morphology after the extra molt. A close examination of the post-imago molting females revealed that their oviduct openings were all blocked by larval or pupal skin and thus unable to lay eggs. The reproductive stress may invoke an endocrine disorder and lead to an extra molt. We propose that L. minor females retain their prothoracic glands even as adults, allowing them to molt as adults under certain environmental or physiological conditions. Thus, neoteny of L. minor is reflected in both the external morphology as well as the internal physiology. The possible developmental changes associated with the evolution of neoteny are discussed.

Trajectory planning and optimization of the bionic mantis robot front leg

In this paper, a manipulator of the bionic mantis robot is designed inspired by the anatomical structure of the mantis front leg. A geometrical method is utilized to calculate the forward kinemics. Then, by analyzing the mantis motion video frame by frame, each of the front leg joints angles is measured in crawling and preying motion, which are used as interpolation conditions to solve the planned trajectory for manipulator by cubic spline interpolation. In some circumstance, the planned joint angles may exceed its limitation. By undermining the interpolation conditions, the problem is transformed from solving a cubic spline function to optimization. Finally, particle swarm optimization with variable inertia weight is introduced to optimize the planned trajectory. The result indicates that the trajectory, smoother after optimization could effectively imitate the motion of mantis front leg within the joint rotation range, which lays the basis for further research on the motion control.

<p class="Body"><strong>Review of free-living predatory cheyletid mites (Acari: Cheyletidae) of Western Siberia, Russia</strong></p>

Investigation of diversity of free-living predatory mites of the family Cheyletidae in Western Siberia, Russia, undertaken for the first time, has recorded 10 species, of which eight species are new for this region. Description of a new species Eutogenes bicornis sp. nov. includes all active stages; a male of Cheletomimus (Hemicheyletia) recki (Volgin, 1966) comb. nov. is redescribed and its remanining active stages are described for the first time; Cheyletus rashtiensis Salarzehi et al. 2018 is recorded from Russia for the first time, and its female is redescribed, and tritonymph is described for the first time; Chelacheles apanaskevichi Bochkov and Abramov, 2016, Cheletacarus raptor Volgin, 1961, Paracheyletia pyriformis (Banks, 1904), Cunliffella whartoni (Baker, 1949), and Bothrocheyla pavlovskyi (Volgin, 1964) are recorded from Western Siberia for the first time. Nomenclature of some setal structures of legs is discussed.

Gate Driver for Wide-Bandgap Power Semiconductors With Small Negative Spike and Switching Ringing in Zero-Voltage Switching Circuit

Because SiC MOSFET-based zero-voltage switching (ZVS) power converter circuits provide high-speed switching, high power density and high efficiency can be achieved. However, an undesired negative spike is formed at the gate-source voltage owing to the crosstalk phenomenon in leg structures, such as half-bridge switch configurations, during high-speed switching. Additionally, ringing voltage occurs owing to resonance between the snubber capacitor and the common source inductance of the SiC MOSFET. Because SiC MOSFETs have a lower gate voltage rating than conventional Si devices, it is essential to reduce the negative spike and ringing voltages to ensure reliability. In this paper, the gate driver circuit is proposed for reducing the negative spike and ringing voltages of the gate-source in ZVS circuits. Because the proposed gate driver circuit provides an effective impedance path for each section through an active switch, a stable driving voltage range of the gate-source can be achieved. To verify the proposed gate driver circuit, an accurate simulation model of the 3-pin SiC MOSFET package is proposed, and the validity of the proposed model is verified through comparison of the simulated waveforms with experimental waveforms. The performance of the proposed gate driver circuit is verified through PSpice simulation.

Lower leg muscle structure and function are altered in long-distance runners with medial tibial stress syndrome: a case control study

BackgroundMedial tibial stress syndrome (MTSS) is a common lower leg injury experienced by runners. Although numerous risk factors are reported in the literature, many are non-modifiable and management of the injury remains difficult. Lower leg muscle structure and function are modifiable characteristics that influence tibial loading during foot-ground contact. Therefore, this study aimed to determine whether long-distance runners with MTSS displayed differences in in vivo lower leg muscle structure and function than matched asymptomatic runners.MethodsLower leg structure was assessed using ultrasound and a measure of lower leg circumference to quantify muscle cross-sectional area, thickness and lean lower leg girth. Lower leg function was assessed using a hand-held dynamometer to quantify maximal voluntary isometric contraction strength and a single leg heel raise protocol was used to measure ankle plantar flexor endurance. Outcome variables were compared between the limbs of long-distance runners suffering MTSS (n = 20) and matched asymptomatic controls (n = 20). Means, standard deviations, 95 % confidence intervals, mean differences and Cohen’s d values were calculated for each variable for the MTSS symptomatic and control limbs.ResultsMTSS symptomatic limbs displayed a significantly smaller flexor hallucis longus cross-sectional area, a smaller soleus thickness but a larger lateral gastrocnemius thickness than the control limbs. However, there was no statistical difference in lean lower leg girth. Compared to the matched control limbs, MTSS symptomatic limbs displayed deficits in maximal voluntary isometric contraction strength of the flexor hallucis longus, soleus, tibialis anterior and peroneal muscles, and reduced ankle plantar flexor endurance capacity.ConclusionsDifferences in lower leg muscle structure and function likely render MTSS symptomatic individuals less able to withstand the negative tibial bending moment generated during midstance, potentially contributing to the development of MTSS. The clinical implications of these findings suggest that rehabilitation protocols for MTSS symptomatic individuals should aim to improve strength of the flexor hallucis longus, soleus, tibialis anterior and peroneal muscles along with ankle plantar flexor endurance. However, the cross-sectional study design prevents us determining whether between group differences were a cause or effect of MTSS. Therefore, future prospective studies are required to substantiate the study findings.

Türkiye’de Yetiştirilen Siyah Alaca İneklerin Doğrusal Tip Özellikleri, Birinci Laktasyon Karlılığı ve Verim Özellikleri Arasındaki Genotopik Korelasyonlar

Amaç: Bu çalışmanın amacı, ıslah programlarında kullanılmak üzere doğrusal tip özellikleri, verim özellikleri ve birinci laktasyon karlılığı arasındaki genetik korelasyonların tespitini yapmaktır.Materyal ve Metot: Araştırma 2012-2017 yılları arasında Hatay ilinde yürütülmüştür. Araştırmada toplam 810 baş birinci laktasyonda olan inek kullanılmıştır. Genetik parametrelerinin varyans ve kovaryanslarının analizi ise Multivariate Limited Maximum Likelihood testi ile gerçekleştirilmiştir.Bulgular: Ortalama inek başına birinci laktasyon net kar, 305-gün süt verimi, ilk buzağılama yaşı, ilk tohumlamada gebe kalma oranı ve kolay doğum oranı 540 US$, 6008 kg, 793 gün, %61.6 ve %91.7 olarak belirlenmiştir. Doğrusal tip özellikleri ile verim özelliklerinin kalıtım dereceleri sırasıyla; 0.10-0.42 ve 0.04-0.39 arasında tahmin edilmiştir. Birinci laktasyon karlılığı ile doğrusal tip özellikleri arasındaki genetik korelasyonlar -0.08 ve 0.42 arasında, birinci laktasyon karlılığı ile verim özellikleri arasındaki korelasyonlar 0.06 ve 0.34. arasında tahmin edilmiştir. Birinci laktasyon karlılığı ile en yüksek korelasyonu meme merkez bağı (0.42) gösterirken, en düşük korelasyonu meme derinliği (-0.08) göstermiştir. Yine birinci laktasyon karlılığı ile en yüksek korelasyonu süt proteini verimi (0.34) gösterirken, en düşük korelasyonu ilk tohumlamada gebe kalma oranı (0.09) göstermiştir. Doğrusal tip özellikleri ile verim özellikleri arasındaki genetik korelasyonlar -0.42 (Ayak açısı ve ilk tohumlamada gebe kalma oranı) ile 0.49 (Sütçü tip özelliği ve 305-gün süt verimi) arasında değişiklik göstermiştir.Sonuç: Araştırma sonuçları, birinci laktasyondaki daha fazla sütçü tipe sahip, ön meme bağlantısı güçlü, güçlü ayak ve bacak yapısına sahip ineklerin, birinci laktasyonda daha karlı olduklarını ve süt sığırı ıslah programlarında doğrusal tip özellikleri ile verim özellikleri arasındaki bu genetik korelasyonlardan yararlanılarak, daha isabetli seleksiyon yapılabileceğini ortaya koymuştur.

Control of Three-Axis Manipulator Placed on Heavy-Duty Pentapod Robot

Research on the effective use of joint-legged robots continues rapidly in many sectors. However, studies on pentapod robots are rare. In this study, a heavy-duty 5-legged robot on which a manipulator's arm with 3-axis and rotating joints is placed was modeled in a Matlab Simscape Multibody environment. The walking simulations of the robot and the position control of the manipulator arm were carried out. PID control method was used for the control of the joints. In order to minimize the vibrations of the base and the gripper end, a suitable gait sequence for 5 leg structure was formed. The effects of vibrations in the robot's base during the walk on manipulator position control are presented graphically and the results are discussed.

PSI-35 Foot and hair shedding scores of crossbred cattle grazing native rangeland differ by age group

Abstract Structural soundness is crucial to improve productivity and longevity of beef cattle in rangeland landscapes. In addition, hair shedding scores are utilized to select for heat tolerant cattle. Thus, the objective of this study was to collect data indicative of cattle adaptability to extensive rangeland landscapes in the Cal Poly beef cattle herd. Three trained technicians assigned claw set, foot angle and hair shedding scores. All data were collected over a 2-day period (n = 3 ranch locations) and foot scores were only collected from females (n = 211) that were at least 1 year of age. Each female was assigned a score for foot angle and claw set (1–9, 5 being ideal). A hair shedding score was also allocated (1–5, 1 = 0% winter coat, 5 = 100% winter coat) to both cows and calves of dams assigned to different age groups. Cattle were retrospectively assigned to a group based on age (Young = 2–3 years of age, Moderate = 4–7 years of age, Old = 8+ years of age) and data were analyzed with the main effects of ranch location and cow age group. Ranch location had no impact (P > 0.05) on foot score or hair shedding score. Cow age group had a significant impact (P < 0.01) on claw set, with young cows exhibiting a lower and more ideal foot score. However, cow age had no effect on hoof angle (P = 0.23). Young cows had a greater (P < 0.001) hair shedding score than their counterparts. Calf hair shedding score was not different (P ≥ 0.23) among dam age groups or ranch locations. Thus, these data indicate that feet and leg structure is compromised as cows age, and younger cows with higher hair shedding scores may lack adaptability to heat stress.

Structural Design and Crawling Pattern Generator of a Planar Quadruped Robot for High-Payload Locomotion.

Load capacity is an important index to reflect the practicability of legged robots. Existing research into quadruped robots has not analyzed their load performance in terms of their structural design and control method from a systematic point of view. This paper proposes a structural design method and crawling pattern generator for a planar quadruped robot that can realize high-payload locomotion. First, the functions required to evaluate the leg’s load capacity are established, and quantitative comparative analyses of the candidates are performed to select the leg structure with the best load capacity. We also propose a highly integrated design method for a driver module to improve the robot’s load capacity. Second, in order to realize stable load locomotion, a novel crawling pattern generator based on trunk swaying is proposed which can realize lateral center of mass (CoM) movement by adjusting the leg lengths on both sides to change the CoM projection in the trunk width direction. Finally, loaded crawling simulations and experiments performed with our self-developed quadruped robot show that stable crawling with load ratios exceeding 66% can be realized, thus verifying the effectiveness and superiority of the proposed method.

Pseudanuretes anfoozi n. sp. (Copepoda: Siphonostomatoida: Caligidae) from the yellowbar angelfish Pomacanthus maculosus (Forsskål) in coral reefs off Iraq.

A new species of Pseudanuretes Yamaguti, 1936 (Copepoda: Caligidae) parasitic on the gills of the yellowbar angelfish Pomacanthus maculosus (Forsskål) from a coral reef off Iraq, north-western Arabian Gulf, is described. Pseudanuretes anfoozi n. sp. belongs within a group of species characterised by the spear-like structure of leg 4. Morphologically P. anfoozi n. sp. is similar to P. papernai Kabata & Deets, 1988 in possessing an armature of I,6 on the third exopodal segment of leg 2 rather than I,7 in the other species of this group. However, P. anfoozi n. sp. can be distinguished from P. papernai by the possession of only 5 caudal setae instead of 6, and in the shape of the caudal rami, which are shorter and wider in new species. In addition, these two species differ in the shape of the genital complex of the adult female.

Functional diversity of attachment and grooming leg structures is retained in all but the smallest insects

AbstractMiniaturization strongly affects functional morphology. Whereas some anatomical structures are barely affected by scaling, others can fundamentally change as the body becomes ever smaller. No prior study has focused on the effect of miniaturization on grooming and attachment structures in Hymenoptera, which can be highly diverse and complex. Through comparative description of the legs of the extremely small wasps of the families Mymaridae and Trichogrammatidae, we evaluate the functional and phylogenetic patterns concerning possible functional effects of miniaturization. On the one hand, the studied species retain some features characteristic of other Chalcidoidea, while on the other, they display some parallelisms associated with miniaturization in leg structure. These observations support a two‐stage morphocline of miniaturization, wherein the first stage is characterized by the preservation of structural complexity and retention of all basic functions, as for instance in examined Megaphragma and the females of Dicopomorpha. The second stage is characterized by a significant simplification, with the loss of redundant non‐essential functions, as observed for the males of Dicopomorpha, which have grossly reduced leg structures, including total loss cleaning devices. Whether these stages are ordered or unordered should be evaluated in future study. Functional optimization of attachment in male Dicopomorpha is indicated by the highly derived mushroom‐shaped tarsi, complemented by novel grappling spurs on the hindfeet, possibly for copulation. Our observations underline adaptive trade‐offs in the expression of complex and multifunctional leg structures at extreme scales.

Economy, energy, exergy and mechanical study of co-axial ring shape configuration of legs as a novel structure for cylindrical thermoelectric generator

The n-type and p-type leg structure of any conventional thermoelectric module are in the form of filled rectangular shape which are placed next to the each other (see graphical abstract). In this paper, hollow cylindrical configuration is investigated as a novel leg structure for thermoelectric module in which the n-type and p-type legs are placed co-axial inside each other. A validated 3D numerical simulation was employed to investigate the proposed structure from thermal, economic, exergetic and mechanical viewpoints. The cylindrical ring-shape co-axial configuration can be made in different azimuthal angle, slant angle and width ratio all of which are probed in this research under different boundary conditions. The ring shape structure is able to reduce the thermal-stresses level without the reduction of thermal efficiency. Results indicate that the increment of hot side temperature can improve the output power and conversion efficiency of the cylindrical thermoelectric generator (CTEG) device but reduces the mechanical reliability of the system. It addition, with increment of slant angle of thermoelectric legs, the maximum Von Mises stress in the legs increases and power output of the CTEG is improved. The increase of the width ratio leads to the improvement of the output power and reduction of conversion and exergy efficiencies. Moreover, it is proved that the azimuthal angle of CTEG device has minor impact on the conversion and exergy efficiencies. It is found that the Von Mises stress attains the peak values in the contact regions between wielding layers and hot sides of the legs.

Water strider females use individual experience to adjust jumping behaviour to their weight within physical constraints of water surface tension

Different species of water striders match leg speeds to their body sizes to maximize their jump take off velocity without breaking the water surface, which might have aided evolution of leg structures optimized for exploitation of the water surface tension. It is not understood how water striders achieve this match. Can individuals modify their leg movements based on their body mass and locomotor experience? Here we tested if water striders, Gerris latiabdominis, adjust jumping behaviour based on their personal experience and how an experimentally added body weight affects this process. Females, but not males, modified their jumping behaviour in weight-dependent manner, but only when they experienced frequent jumping. They did so within the environmental constraint set by the physics of water surface tension. Females’ ability to adjust jumping may represent their adaptation to frequent increases or decreases of the weight that they support as mating bouts, during which males ride on top of females, start or end, respectively. This suggests that natural selection for optimized biomechanics combined with sexual selection for mating adaptations shapes this ability to optimally exploit water surface tension, which might have aided adaptive radiation of Gerromorpha into a diversity of semiaquatic niches.

CaseCrawler: A Lightweight and Low-Profile Crawling Phone Case Robot

The CaseCrawler is a lightweight and low-profile movable platform with a high payload capacity; it is capable of crawling around carrying a smartphone. The body of the robot resembles a phone case but it has crawling legs stored in its back. It is designed with a deployable, in-plane transmission that is capable of crawling locomotion. The CaseCrawler's leg structure has a knee joint that can passively bend only in one direction; this allows it to sustain a load in the other direction. This anisotropic leg allows a crank slider to be used as the main transmission for generating the crawling motion; the crank slider generates a motion only within a 2D plane. The crank slider deploys the leg when the slider is pushed and retracts it when pulled; this enables a low-profile case that can fully retract the legs flat. Furthermore, by being restricted to swinging within a plane, the hip joint is highly resistant to off-axis deformation, this results in a high payload capacity. As a result, the CaseCrawler has a body thickness of 16 mm (the transmission without the gearbox is only 1.5 mm) and a total weight of 22.7 g; however, it can carry a load of over 300 g, which is 13 times its own weight. To show the feasibility of the robot for use in real-world applications, in this study, the CaseCrawler was employed as a movable platform that carries a 190 g mass, including a smartphone and its cover. This robot can crawl around with the smartphone to enable the phone to charge itself on a wireless charging station. In the future, if appropriate sensing and control functions are implemented, the robot will be able to collect data or return to the owner when needed.

Fatigue life prediction on jacket leg structure subjected to axial and wave loads

Fixed jacket platform is an offshore structure consists of many elements such as leg and braces. Both legs and braces play an important role to support the structure from internal and external loads like structure its self and wave loads. Especially for jacket leg, the deck load is distributed to all jacket leg to support deck structure. Besides, jacket leg also resists wave loads in horizontal direction. Due to the axial load caused by deck and horizontal load caused by wave, these loads act periodically on jacket leg. Therefore, the analysis of fatigue life to jacket leg should be performed for structural design. The present study focuses on fatigue life prediction on jacket leg under axial and wave load. The numerical method is conducted to analyze fatigue life on jacket leg. It is found that the fatigue life due to axial and wave loads are 185 and 108 years, respectively.

Novel design of a family of legged mobile landers based on decoupled landing and walking functions

The lander has made a significant contribution to soft landings and exploration of an extraterrestrial surface. To further expand its detection range and meet the needs of base construction in the future, it is necessary to design a legged mobile lander (LML) that lets the fixed lander walk. In this paper, a decoupled functions synthesis method (DFSM), which means the decoupled landing and walking functions for LMLs, is proposed: it uses separate structures of landing leg (LL) and walking leg (WL) to perform landing and walking functions. The structure of the Chang’e lander’s leg is selected and designed as the LL. The structures of WLs are determined and presented by the Lie group type synthesis method. In accordance with the combination principle, the landing-walking leg (LWL) for LMLs is designed by combining the structures of a LL and a WL. The structures of a family of LMLs are achieved by assembling the same or different structures of legs. Furthermore, the actuated joints are assigned according to the principle for selecting the actuated joint and one case of LWL is selected as an optimized type by the qualitative evaluation. Finally, one leg of LMLs is taken as an example to analyze the properties and abilities during different stages.