Quadrupedal Gait Research Articles

A biomechanical approach on the optimal stance of Anhanguera piscator (Pterodactyloidea) and its implications for pterosaur gait on land

The stance of pterosaurs on land is traditionally a controversial question. Here, we show that pterosaurs like Anhanguera piscator were quadrupeds. An osteological model of A. piscator was three-dimensionally built in digital space. The reconstructed muscles of its pelvic girdle were then placed on their points of origin and insertion to allow the biomechanical calculations to find the most efficient stance on land to be performed. The hindlimb readjustment (i.e. the repositioning of the hindlimb according to the achieved results) led to a pelvic counterclockwise displacement at 10°, which means that the ilium previously placed at 0° regarding an axis parallel to the ground was moved (and so the whole pelvis) 10° up from the preacetabular process. This new position prevents A. piscator from having a fully upright stance. A 10° displacement of the pelvic girdle would compel the forelimbs to be highly sprawled. Therefore, this study affords A. piscator having a quadrupedal gait and demonstrates that a bipedal stance is not viable once the lever arm values decrease abruptly both for extensor and flexor muscles during the femoral extension. This is the first time this approach is used to shed light on this question.

Metapodial or Phalanx? An Evolutionary and Developmental Perspective on the Homology of the First Ray's Proximal Segment

The first mammalian metapodial (MP1) has periodically been argued to actually be a phalanx, because the first ray has one less element than the four posterior rays, and because the MP1 growth plate is proximal like those of all phalanges, rather than distal as in metapodials 2-5. However, growth plates are formed at both ends in non-therian tetrapod metapodials, and phylogenetic analysis demonstrates that growth plate loss is a therian synapomorphy that postdates the establishment of the mammalian phalangeal formula. These data, along with results of developmental and morphological studies, suggest that the MP1 is not a phalanx. The singular, proximal growth plates in MPs 2-5 are likely to be an adaptation to dynamic erect quadrupedal gait which was characterized by conversion of the posterior metapodials into rigid struts with the carpus/tarsus. While the adaptive significance of the reversed ossification of MP1 is less clear, we present three functional/developmental hypotheses.

Prevention of cartilage degeneration and gait asymmetry by lubricin tribosupplementation in the rat following anterior cruciate ligament transection

To investigate whether cartilage degeneration is prevented or minimized in a rat model of anterior cruciate ligament (ACL) injury following a single dose-escalated intraarticular injection of lubricin derived from human synoviocytes in culture. Unilateral ACL transection (ACLT) of the right hind limb was performed in Lewis rats (n = 56). Control animals underwent a capsulotomy alone, leaving the ACL intact (n = 11). Intraarticular injections (50 μl/injection) of phosphate buffered saline (PBS; n = 14 rats) and human synoviocyte lubricin (1,600 μg/ml; n = 14 rats) were performed on day 7 postsurgery. Animals were killed on day 70 postsurgery. Histologic specimens were immunoprobed for lubricin and sulfated glycosaminoglycans. Urinary C-telopeptide of type II collagen (CTX-II) levels were measured on days 35 and 70 postsurgery. Hind limb maximum applied force was determined using a variable resistor walkway to monitor quadruped gait asymmetries. Increased immunostaining for lubricin in the superficial zone and on the surface of cartilage was observed in lubricin-treated and control animals but not in PBS-treated or untreated animals with ACLT. On days 35 and 70 after surgery, urinary CTX-II levels in human synoviocyte lubricin-treated animals were lower than in untreated and PBS-treated animals (P < 0.005 and P < 0.001, respectively). Animals with ACLT treated with human synoviocyte lubricin and control animals distributed their weight equally between hind limbs compared to PBS-treated or untreated animals (P < 0.01). Our findings indicate that a single intraarticular injection of concentrated lubricin following ACLT reduces type II collagen degradation and improves weight bearing in the affected rat joint. These findings support the practice of tribosupplementation with lubricin for retarding cartilage degeneration and possibly the development of posttraumatic osteoarthritis.

Gait definition and successive gait-transition method based on energy consumption for a quadruped

In nature, to realize the smooth motion for different speeds, the continuous gait transition is usually required for the quadrupeds. Thus, the gait simulation of quadrupeds is a requisite step to obtain the stable and energy-efficient gait for the walking machines. In this paper, the definitions of the two gait parameters, phasic difference and duty factor are presented, which can determine the gait of the quadrupeds. Then, several typical gaits of the quadrupeds are analyzed such that the seven standard gaits and corresponding parameters are summarized. Additionally, the variance law of the two parameters, which determine the relationship of gait transition, is analyzed. Furthermore, the quadruped gait derivative spectrum (QGDS) is proposed and the gait definition of the quadrupeds is presented. To minimize the power consumption, the choice criterion of gait, the optimal gait in terms of the motion speed, duty factory, and power consumption for the walking machines, is developed. Last, the continuous variance of the gait is implemented by the simulation of the gait transition from walk to trot, which evaluate the choice criterion and transition of gait.

Computer simulation and dynamic modeling of a quadrupedal pronking gait robot with SLIP model

In this study, a quadrupedal pronking gait robot modeling was carried out with Spring Loaded Inverted Pendulum model in stance phase. This is achieved by solving a natural problem in which the main goal is to enable the robot to walk and run in a stable condition regardless of the environmental conditions. In order to solve this problem, dynamic model and control of a quadrupedal robot were realized for a pronking gait. The stance and flight phase dynamic structures were solved in a sequential closed loop to obtain the equation of motion for pronking gait. Spring Loaded Inverted Pendulum model was used as a dynamic model to simplify the simulation, dynamic locomotion and experimental works of the system, and also to simplify the pronking gait concept. The quadrupedal robot with pronking gait was controlled by proportional-derivative control algorithm. As a result, all computer simulations have shown that the proposed control actions and methods are more effective and make the system control quite easy and successful.

Features of hand-foot crawling behavior in human adults

Interlimb coordination of crawling kinematics in humans shares features with other primates and nonprimate quadrupeds, and it has been suggested that this is due to a similar organization of the locomotor pattern generators (CPGs). To extend the previous findings and to further explore the neural control of bipedal vs. quadrupedal locomotion, we used a crawling paradigm in which healthy adults crawled on their hands and feet at different speeds and at different surface inclinations (13°, 27°, and 35°). Ground reaction forces, limb kinematics, and electromyographic (EMG) activity from 26 upper and lower limb muscles on the right side of the body were collected. The EMG activity was mapped onto the spinal cord in approximate rostrocaudal locations of the motoneuron pools to characterize the general features of cervical and lumbosacral spinal cord activation. The spatiotemporal pattern of spinal cord activity significantly differed between quadrupedal and bipedal gaits. In addition, participants exhibited a large range of kinematic coordination styles (diagonal vs. lateral patterns), which is in contrast to the stereotypical kinematics of upright bipedal walking, suggesting flexible coupling of cervical and lumbosacral pattern generators. Results showed strikingly dissimilar directional horizontal forces for the arms and legs, considerably retracted average leg orientation, and substantially smaller sacral vs. lumbar motoneuron activity compared with quadrupedal gait in animals. A gradual transition to a more vertical body orientation (increasing the inclination of the treadmill) led to the appearance of more prominent sacral activity (related to activation of ankle plantar flexors), typical of bipedal walking. The findings highlight the reorganization and adaptation of CPG networks involved in the control of quadrupedal human locomotion and a high specialization of the musculoskeletal apparatus to specific gaits.

Phenotypical spectrum of cerebellar ataxia associated with a novel mutation in the CA8 gene, encoding carbonic anhydrase (CA) VIII

We define the neurological characteristics of familial cases from multiple branches of a large consanguineous family with cerebellar ataxia, mental retardation (MR), and dysequilibrium syndrome type 3 caused by a mutation in the recently cloned CA8 gene. The linkage analysis revealed a high logarithm of the odds (LOD) score region on 8q that harbors the CA8 in which a novel homozygous c.484G>A (p.G162R) mutation was identified in all seven affected members. The patients had variable cerebellar ataxia and mild cognitive impairment without quadrupedal gait. The brain MRI showed variable cerebellar volume loss and ill-defined peritrigonal white matter abnormalities. The Fluorodeoxyglucose Positron Emission Tomography (FDG PET) revealed hypometabolic cerebellar hemispheres, temporal lobes, and mesial cortex. This report expands the neurological and radiological phenotype associated with CA8 mutations. CA8 involvement should be considered in the differential diagnosis of other genetically unresolved autosomal recessive cerebellar ataxias.

Study on Kinematics-Based Symbolic Computation–Driven Quadruped Robot Gait Simulation System

The paper presents a dedicated kinematics-based simulation system for quadruped robot gait study, named as TQRSS. The system employs Ginac’s symbolic computation technology, making it possible on-line planning and help concentrate on robot gait planning and parameter adjusting. The Taishan quadruped robot’s kinematics analysis is also presented.

BigDog-Inspired Studies in the Locomotion of Goats and Dogs

Collision-based expenditure of mechanical energy and the compliance and geometry of the leg are fundamental, interrelated considerations in the mechanical design of legged runners. This article provides a basic context and rationale for experiments designed to inform each of these key areas in Boston Dynamic's BigDog robot. Although these principles have been investigated throughout the past few decades within different academic disciplines, BigDog required that they be considered together and in concert with an impressive set of control algorithms that are not discussed here. Although collision reduction is an important strategy for reducing mechanical cost of transport in the slowest and fastest quadrupedal gaits, walking and galloping, BigDog employed an intermediate-speed trotting gait without collision reduction. Trotting, instead, uses a spring-loaded inverted pendulum mechanism with potential for storage and return of elastic strain energy in appropriately compliant structures. Rather than tuning BigDog's built-in leg springs according to a spring-mass model-based virtual leg-spring constant , a much stiffer distal leg spring together with actuation of the adjacent joint provided good trotting dynamics and avoided functional limitations that might have been imposed by too much compliance in real-world terrain. Adjusting the directional compliance of the legs by adopting a knee-forward, elbow-back geometry led to more robust trotting dynamics by reducing perturbations about the pitch axis of the robot's center of mass (CoM). BigDog is the most successful large-scale, all-terrain trotting machine built to date and it continues to stimulate our understanding of legged locomotion in comparative biomechanics as well as in robotics.

A robust sauropodomorph specimen from the Upper Triassic of Argentina and insights on the diversity of the Los Colorados Formation

The Late Triassic rocks document the first steps of the early dinosaur evolutionary radiation. Although the oldest dinosaurs were not abundant in their assemblages, sauropodomorphs achieved a wide taxonomic diversity and high abundance towards the Triassic–Jurassic boundary. In South America, this pattern is documented in the Ischigualasto-Villa Unión Basin of northwestern Argentina, in which dinosaurs achieved a numerical dominance over other tetrapods during the deposition of the upper levels of the late Norian-Rhaetian Los Colorados Formation. In this contribution we enrich the faunal list of this assemblage with the description of a new medium-sized basal sauropod specimen with a very robust tibial morphology. This new specimen differs from the other known sauropodomorphs described for the Los Colorados Formation and increases the alpha-diversity recorded for this group. A phylogenetic analysis recovered the new specimen at the base of Sauropoda and closely related to Lessemsaurus, Antetonitrus, and other basal sauropods. These results match with the high degree of robustness observed in the tibia of the specimen reported here, which closely approaches the morphology documented for other basal sauropods and departs from the morphospace occupied by non-sauropod sauropodomorphs. A two step pattern of tibia robustness increase is observed in the sauropodomorph phylogeny, a pattern that coincides and could be related with the acquisition of more habitual quadrupedal gait achieved by basal sauropods.

A collisional perspective on quadrupedal gait dynamics

The analysis of terrestrial locomotion over the past half century has focused largely on strategies of mechanical energy recovery used during walking and running. In contrast, we describe the underlying mechanics of legged locomotion as a collision-like interaction that redirects the centre of mass (CoM). We introduce the collision angle, determined by the angle between the CoM force and velocity vectors, and show by computing the collision fraction, a ratio of actual to potential collision, that the quadrupedal walk and gallop employ collision-reduction strategies while the trot permits greater collisions. We provide the first experimental evidence that a collision-based approach can differentiate quadrupedal gaits and quantify interspecific differences. Furthermore, we show that this approach explains the physical basis of a commonly used locomotion metric, the mechanical cost of transport. Collision angle and collision fraction provide a unifying analysis of legged locomotion which can be applied broadly across animal size, leg number and gait.

Mina: A Sensorimotor Robotic Orthosis for Mobility Assistance

While most mobility options for persons with paraplegia or paraparesis employ wheeled solutions, significant adverse health, psychological, and social consequences result from wheelchair confinement. Modern robotic exoskeleton devices for gait assistance and rehabilitation, however, can support legged locomotion systems for those with lower extremity weakness or paralysis. The Florida Institute for Human and Machine Cognition (IHMC) has developed the Mina, a prototype sensorimotor robotic orthosis for mobility assistance that provides mobility capability for paraplegic and paraparetic users. This paper describes the initial concept, design goals, and methods of this wearable overground robotic mobility device, which uses compliant actuation to power the hip and knee joints. Paralyzed users can balance and walk using the device over level terrain with the assistance of forearm crutches employing a quadrupedal gait. We have initiated sensory substitution feedback mechanisms to augment user sensory perception of his or her lower extremities. Using this sensory feedback, we hypothesize that users will ambulate with a more natural, upright gait and will be able to directly control the gait parameters and respond to perturbations. This may allow bipedal (with minimal support) gait in future prototypes.

Carbonic Anhydrase Related Protein VIII and its Role in Neurodegeneration and Cancer

Mammalian carbonic anhydrase (α-CA) gene family comprises sixteen isoforms, thirteen of which are active isozymes and three isoforms lack classical CA activity of reversible hydration of CO(2) due to absence of one or more histidine residues required for CA catalytic activity. The inactive isoforms are known as carbonic anhydrase related proteins (CARPs) VIII, X and XI. Among these three, CARP VIII was reported first in 1990 from a mouse brain cDNA library and is well studied structurally as well as functionally compared to CARP X and XI. CARP VIII is an intriguing protein and is widely distributed and evolutionarily well-conserved across the species. It is mainly expressed in the Purkinje cells of cerebellum and in wide variety of other tissues both in mouse and human. CARP VIII has been linked to development of colorectal and lung cancers in humans, and overexpression of CARP VIII has been observed in several other cancers. A mutation in the CA8 gene has been associated with ataxia, mild mental retardation and quadrupedal gait in humans and with lifelong gait disorder in mice, suggesting an important role for CARP VIII in the brain. However, the precise function of CARP VIII is still an enigma. The present review article describes the previous data on CARP VIII, including its structure, role in neurodegeneration and cancer; and bioinformatic and expression analyses recently performed in our laboratory.

Novel VLDLR microdeletion identified in two Turkish siblings with pachygyria and pontocerebellar atrophy

Congenital ataxia with cerebellar hypoplasia is a heterogeneous group of disorders that presents with motor disability, hypotonia, incoordination, and impaired motor development. Among these, disequilibrium syndrome describes a constellation of findings including non-progressive cerebellar ataxia, mental retardation, and cerebellar hypoplasia following an autosomal recessive pattern of inheritance and can be caused by mutations in the Very Low Density Lipoprotein Receptor (VLDLR). Interestingly, while the majority of patients with VLDL-associated cerebellar hypoplasia in the literature use bipedal gait, the previously reported patients of Turkish decent have demonstrated similar neurological sequelae, but rely on quadrupedal gait. We present a consanguinous Turkish family with two siblings with cerebellar atrophy, predominantly frontal pachygyria and ataxic bipedal gait, who were found to have a novel homozygous deletion in the VLDLR gene identified by using high-density single nucleotide polymorphism microarrays for homozygosity mapping and identification of CNVs within these regions. Discovery of disease causing homozygous deletions in the present Turkish family capable of maintaining bipedal movement exemplifies the phenotypic heterogeneity of VLDLR-associated cerebellar hypoplasia and ataxia.

四脚ロボット「Rush」を用いたバウンド歩容生成(機械力学,計測,自動制御)

We have been studying on quadruped gait using our quadruped robot "Rush", which has rotational passive joints. Among quadruped gait, "bound gait" is simple and easy to emerge for quadruped robot. Thus, most of researches on quadruped robot running have dealt with bound gait. But, bound gait of most quadruped robot differed from four legged mammals. This paper shows that the bound gait similar to four legged manmals can realized by controlling the position of the center of gravity of the robot body in both simulations and actual experiments.

The first pterosaur trackways from Japan

In 1990, five well-preserved pterosaur trackways were discovered in the Kitadani Formation (Lower Cretaceous) of the Kitadani Dinosaur Quarry, Fukui Prefecture, Japan. They occur on the surface of an isolated dark grey siltstone slab (70 × 50 cm) along with amphibian and bird tracks as well as feeding marks. All pterosaur trackways (a total of 64 imprints) show a clear quadrupedal gait pattern comprising manus and pes prints which reflect their detailed anatomy of the feet. Manus and pes imprint is very small, average 22.6 mm and 21.9 mm long, respectively. The manus has an anteriorly oriented digit I imprint with a medially oriented hook-like sharp claw mark, which makes a high divarication (average 155.4°) between the posteriorly oriented digit III imprint. The high digital abduction clearly shows that digit I of the manus could be more hyper-extended anteriorly than previously thought: spreading the digits as much as possible would provide a more stable contact with substrate as well as better support the center of pterosaur body mass displaced anteriorly. The interdigital webbing of the pes imprint extends from the metatarso-phalangeal joint near to the bases of four claws. As these features clearly distinguish the Kitadani pterosaur trackways from five known ichnospecies of Pteraichnus, we assign them to a new ichnospecies, Pteraichnus nipponensis. Abundant small pterosaur ichnotaxa from Spain, Korea, and Japan indicate that many small pterodactyloid pterosaur species existed in the Early Cretaceous although there is no single skeletal datum yet.

A new transitional sauropodomorph dinosaur from the Early Jurassic of South Africa and the evolution of sauropod feeding and quadrupedalism

Aardonyx celestae gen. et sp. nov. is described from the upper Elliot Formation (Early Jurassic) of South Africa. It can be diagnosed by autapomorphies of the skull, particularly the jaws, cervical column, forearm and pes. It is found to be the sister group of a clade of obligatory quadrupedal sauropodomorphs (Melanorosaurus + Sauropoda) and thus lies at the heart of the basal sauropodomorph-sauropod transition. The narrow jaws of A. celestae retain a pointed symphysis but appear to have lacked fleshy cheeks. Broad, U-shaped jaws were previously thought to have evolved prior to the loss of gape-restricting cheeks. However, the narrow jaws of A. celestae retain a pointed symphysis but appear to have lacked fleshy cheeks, demonstrating unappreciated homoplasy in the evolution of the sauropod bulk-browsing apparatus. The limbs of A. celestae indicate that it retained a habitual bipedal gait although incipient characters associated with the pronation of the manus and the adoption of a quadrupedal gait are evident through geometric morphometric analysis (using thin-plate splines) of the ulna and femur. Cursorial ability appears to have been reduced and the weight bearing axis of the pes shifted to a medial, entaxonic position, falsifying the hypothesis that entaxony evolved in sauropods only after an obligate quadrupedal gait had been adopted.

CA8 Mutations Cause a Novel Syndrome Characterized by Ataxia and Mild Mental Retardation with Predisposition to Quadrupedal Gait

We describe a consanguineous Iraqi family in which affected siblings had mild mental retardation and congenital ataxia characterized by quadrupedal gait. Genome-wide linkage analysis identified a 5.8 Mb interval on chromosome 8q with shared homozygosity among the affected persons. Sequencing of genes contained in the interval revealed a homozygous mutation, S100P, in carbonic anhydrase related protein 8 (CA8), which is highly expressed in cerebellar Purkinje cells and influences inositol triphosphate (ITP) binding to its receptor ITPR1 on the endoplasmatic reticulum and thereby modulates calcium signaling. We demonstrate that the mutation S100P is associated with proteasome-mediated degradation, and thus presumably represents a null mutation comparable to the Ca8 mutation underlying the previously described waddles mouse, which exhibits ataxia and appendicular dystonia. CA8 thus represents the third locus that has been associated with quadrupedal gait in humans, in addition to the VLDLR locus and a locus at chromosome 17p. Our findings underline the importance of ITP-mediated signaling in cerebellar function and provide suggestive evidence that congenital ataxia paired with cerebral dysfunction may, together with unknown contextual factors during development, predispose to quadrupedal gait in humans.

Ballistic Walking Design via Impulsive Control

Mathematical models of a biped and quadruped walking are considered. The planar five-link biped consists of a one-link trunk and two identical two-link legs. In the single support motion swing phase, the biped has five degrees of freedom and is described by a system of nonlinear ordinary differential equations of the 10th order. These equations are written in a visible matrix form. A seven-link planar biped with massless feet is also considered. In this paper, the swing motion of the biped is assumed a ballistic passive one. There are no active torques in the interlink joints during the single support motion—only the gravity force and ground reaction forces are applied to the biped. The problem of design of ballistic swing motion is reduced to the boundary-value problem for the system of nonlinear differential equations with given initial and final configurations and the duration of the half-step. It is assumed that there is no friction in the interlink joints note that the friction in the human joints is very small. Therefore, in the ballistic swing motion the complete energy of the system kinetic energy plus potential one is conserved and the system has the energy integral. Due to this fact some properties of symmetry of ballistic motions are proved. Linearized model can be reduced to the canonical Jordan form. Then the linear boundary-value problem can be solved analytically. Using numerical investigations of the linear model we have animated the biped walking, which occurs similar to the human gait: the transferring leg moves over the support, the legs bend with knees forward, and the trunk makes one vibration during one half-step. All these features have not been prescribed beforehand in the statement of the problem. Iteration process is used to solve the nonlinear boundary-value problem. For some cases, several solutions of this nonlinear problem are found numerically. The symmetry properties of the ballistic motions help to find numerically the solutions of this complex nonlinear problem. The ballistic motion is also designed numerically for the three-dimensional biped model with 6, 8, 9, and finally with 11 degrees of freedom. The double-support phase is assumed an instantaneous one. During this phase there is a collision of the transferring swing leg and the support. Active impulsive torques are applied in the interlink joints at this instant. These impulsive torques and ground reaction forces are described by delta functions of Dirac. Thus, with this impulsive control, most of the efforts are applied in the double-support phase. Formulas for the energy cost of impulsive control actions have been found. Some problems of optimal distribution of the impulsive actions between the joints are discussed. A planar seven-link model of biped with arms is considered. This model consists of a one-link trunk, two identical one-link arms, and two identical two-link legs with point feet. Ballistic gait of this biped model is studied. The goal of this study is to find the optimal amplitude of the arms swinging, minimizing the energy consumption. We show numerically the existence of the optimal amplitude of the arms swinging. Ballistic walking of a quadruped is investigated too. Three types of quadruped gaits, bound, amble, and trot, are considered. For each kind of the gait, ballistic locomotion is designed and energy consumption is evaluated.

Unertan Syndrome: A New Variant of Unertan Syndrome: Running on All Fours in Two Upright-Walking Children

A new variant of Unertan Syndrome (UTS) is described in two Turkish children who exhibit both bipedal and quadrupedal locomotion and have normal cognitive abilities, including speech and intelligence. Quadrupedal locomotion was used by these individuals for rapid motivity when needed. An X-linked autosomal recessive transmission appears to be responsible for the UTS trait, with no intrafamilial marriages. The children did not show any neurological signs and symptoms except for a positive Babinski sign and an inability to perform a tandem walk. The results suggest that quadrupedality may result from using ancestral neural networks when needed. The preference for the quadrupedal gait as a hidden skill may be an example of learned dynamical adaptation to limited motor control, pointing out a phase transition in system dynamical terms. Human quadrupedality may have important consequences regarding human evolution with respect to the transition from quadrupedalism to bipedalism, which is generally recognized as important trait in the hominization process during human evolution.