Locomotion Method Research Articles

Evolution of side-winding locomotion of simulated limbless, wheelless robots

Inspired by the efficient method of locomotion of the rattlesnake Crotalus cerastes, the objective of this work was the automatic design through genetic programming of the fastest possible, side-winding locomotion of simulated limbless, wheelless artifacts. The realism of the simulation is ensured by employing open dynamics engine (ODE), which allows accounting for all the physical forces resulting from the actuators (muscles), friction, gravity, collisions, and joint constraints. The empirically obtained results demonstrate that the complex side-winding locomotion emerges from relatively simple motion patterns of morphological segments (vertebrae). The robustness of automatically evolved locomotion is verified by (i) the reasonable performance degradation when partial damage to the artifact is inflicted, and (ii) the ability to tackle obstacles. Contributing to the better understanding of the unique, side-winding locomotion, this work could be considered as a step toward building real limbless, wheelless robots, featuring unique engineering characteristics, which are able to perform robustly in difficult environments.

Friction manipulation for intestinal locomotion

The importance of colonoscopies on the one hand and the drawbacks of the conventional instrumentation on the other have led to research into alternative colonoscopic devices. The main question for the development of such devices is the method of locomotion along the slippery and flaccid intestinal tube. This paper suggests a new intestinal locomotion method based on friction manipulation between the device and the intestinal wall. A new concept to manipulate friction is described. The concept is based on the active alterations of the friction between the device and the intestinal wall and it is inspired by the locomotion of biological species such as snails and starfish.

Automatic Locomotion Design and Experiments for a Modular Robotic System

This paper presents a design method and experiments for whole-body locomotion by a modular robot. There are two types of locomotion for modular robots: a repeating self-reconfiguration and whole-body motion such as walking or crawling. For whole-body locomotion, designing a control method is more difficult than for ordinary robots because a modular robotic system can form various configurations, each of which has many degrees of freedom. This study proposes a unified framework for automatically designing an efficient locomotion controller suitable for any module configuration. The method utilizes neural oscillators (central pattern generators, CPGs), each of which works as a distributed joint controller of each module, and a genetic algorithm to optimize the CPG network. We verified the method by software simulations and hardware experiments, in which our modular robotic system, named M-TRAN II, performed stable and effective locomotion in various configurations.

지면의 미끄러운 정도에 따른 캐릭터의 걷기 동작 생성

3차원 가상현실 내에서 캐릭터 움직임 동작의 기술은 기존 방식인 키프레임 기법에 의존하던 것이 점차 동작 제어 기법을 활용하고, 보다 사실적이고 자연스러운 움직임을 생성해 내고자 하는 방향으로 발전해 가고 있다. 그러나 이러한 동작 제어 기법을 통해 가상현실의 지형 성질에 따라 적응적인 캐릭터의 동작을 표현하는데 한계가 있다. 즉, 대부분의 가상환경에서 캐릭터의 걷는 움직임은 일정하고 단조로운 동작만을 반복하여 표현하고 있어 관찰자로 하여금 지루함을 느끼게 하고, 지형의 조건이나 형태에 맞지않게 캐릭터의 발끝이 지면에 스며들거나 떠있는 등의 부자연스러운 동작으로 인해 사실감을 저하시킨다. 본 논문에서는 적은 매개변수들과 역운동학 방법을 적용하여 기본 걷기 동작을 표현하고, 지면의 성질을 마찰계수로 대표시켜 지면에 적응적인 걷기 동작의 생성 방법을 제안한다. 제안된 방법에서는 구심력과 마찰계수를 결합한 후, 이를 근거로하여 한 주기 동안의 걷는 동작을 분석하고 이를 기반으로 동작에 필요한 매개변수를 조정하여 지질에 따른 적응적인 캐릭터의 걷기 동작을 생성한다. In 3D virtual environment the description of character' s movement that has utilized the conventional key-frame technique is gradually being developed toward the application of motion control method to generate more realistic and natural motion. Even the motion control method, however, has the limitation for expression of character's motion adapted to the ground properties of virtual world. That is, the walking motions of character are not only, for the most part, so uniform simple and repeated often as to feel to be tedious, but also the unnatural motion in which the tips of the toes soak through a plane or float in the air discording with the conditions of terrain lowers the semblance of reality. This paper proposes an adaptive motion control method for human figure locomotion in virtual environments or games, in which the walking motion is dynamiccally adapted to the ground's sliding properties. We compute an optimal parameters for one cycle of walking motion adapted to the ground properties by combining the coefficient of friction and centripetal force, and therefrom we induce a set of nonskid speed corresponding to various sliding properties of the ground.

Understanding Snakelike Locomotion Through a Novel Push-Point Approach

Limbless locomotion reveals increasing interest among locomotion methods inspiring mobile robots. This paper deals with the lateral undulation, one type of terrestrial snakelike locomotion. It represents the first part of a research project based on a biologically inspired approach. The purpose, in this first place, is to cover the physical principles involved in lateral undulation. Following an overview of the lateral undulation as it occurs in nature, the authors consider a generic planar mechanism and a related environment that suit to satisfy the fundamental mechanical phenomenon observed in the locomotion of terrestrial snakes. Application of a relatively simple control law is tested through dynamic simulations. In the second place, the results of this introductory study are going to be used in the research of an appropriate technological solution for an artificial snake exerting lateral undulation. The approach presented differs from other works on the subject in the sense that it does not require any wheeled structure.

Crocodilian bone-tendon and bone-ligament interfaces

We investigated bone-tendon (27 sites) and bone-ligament (12 sites) interfaces in six pairs of crocodile limbs and girdles under light microscopy. These crocodilian interfaces often included a direct, unmediated insertion in which the tendon or ligament fibers inserted directly into the bone itself without fibrocartilaginous mediation. This was quite different from the usual direct insertion known in mammals and lizards. Fibrocartilaginous tissue at the bone-tendon interface is generally believed to protect tendon fibers against shear stress. Other types of insertions were found in the crocodilian epiphyses, namely, hyaline cartilage and pseudofibrocartilaginous insertions. Notably, a thick periosteum/perichondrium and subchondral layer was involved at both interfaces. The thick periosteum/perichondrium seemed to form along the epiphyseal hyaline cartilage and might function in replacement of fibrocartilaginous tissues. Crocodilian thick periosteum/perichondrium would be expected to reinforce the limb and girdle bones--especially their epiphyses, in which secondary centers of ossification are absent. The subchondral layer--a kind of fibrocartilaginous tissue--seemed to play the role of the growth plate in compensating for the absence of secondary centers of ossification. Therefore, we hypothesized that the crocodile-specific bone-tendon interfaces were the result of these specializations of bone development and growth. In crocodiles, the disadvantages of the single ossification center are effectively compensated for by specialized morphologies, including these interfaces. Specialized bone growth provides the crocodile with the largest body size of the recent reptiles and an extremely fast method of locomotion.

Physiological diversity: listening to the large‐scale signal

Physiological diversity: listening to the large‐scale signal

Quantification of the wake of rainbow trout (Oncorhynchus mykiss) using three-dimensional stereoscopic digital particle image velocimetry.

Although considerable progress has been made within the last decade in experimental hydrodynamic analyses of aquatic locomotion using two-dimensional digital particle image velocimetry (two-dimensional DPIV), data have been limited to simultaneous calculation of two out of the three flow velocity variables: downstream (U), vertical (V) and lateral (W). Here, we present the first biological application of stereo-DPIV, an engineering technique that allows simultaneous calculation of U, V and W velocity vectors. We quantified the wakes of rainbow trout (Oncorhynchus mykiss, 16.5-21.5 cm total body length, BL), swimming steadily in a recirculating flow tank at a slow cruising speed of 1.2 BL s(-1). These data extend the comparative basis of current hydromechanical data on the wakes of free-swimming fishes to the salmoniforms and are used to test current hypotheses of fin function by calculations of mechanical performance and Froude efficiency. Stereo-DPIV wake images showed three-dimensional views of oscillating jet flows high in velocity relative to free-stream values. These jet flows are consistent with the central momentum jet flows through the cores of shed vortex rings that have been previously viewed for caudal fin swimmers using two-dimensional DPIV. The magnitude and direction of U, V and W flows in these jets were determined over a time series of 6-8 consecutive strokes by each of four fish. Although the fish swam at the same relative speed, the absolute magnitudes of U, V and W were dependent on individual because of body size variation. Vertical flows were small in magnitude (<1 cm s(-1)) and variable in direction, indicating limited and variable vertical force production during slow, steady, forward swimming. Thus, in contrast to previous data from sunfish (Lepomis macrochirus) and mackerel (Scomber japonicus), the trout homocercal caudal fin does not appear to generate consistent vertical forces during steady swimming. U flows were of the order of 3-6 cm s(-1); lateral flows were typically strongest, with W magnitudes of 4-6 cm s(-1). Such strong lateral flows have also been shown for more derived euteleosts with homocercal caudal fins. The ratios of the magnitudes of wake flow, U/(U+V+W), which is a flow equivalent to mechanical performance, were also dependent on individual and ranged from 0.32 to 0.45, a range similar to the range of mechanical performance values previously determined using standard two-dimensional DPIV methods for caudal fin locomotion by more derived euteleosts. Strong lateral jet flow appears to be a general feature of caudal fin locomotion by teleosts and may reflect the nature of undulatory propulsion as a posteriorly propagated wave of bending. Froude efficiency (eta(p)) was independent of individual; mean eta(p) was 0.74, which is similar to previous findings for trout.

A Self-Reconfigurable Modular Robot: Reconfiguration Planning and Experiments

In this paper we address a reconfiguration planning method for locomotion of a homogeneous modular robotic system and we conduct an experiment to verify that the planned locomotion can be realized by hardware. Our recently developed module is self-reconfigurable. A group of the modules can thus generate various three-dimensional robotic structures and motions. Although the module itself is a simple mechanism, self-reconfiguration planning for locomotion presents a computationally difficult problem due to the many combinatorial possibilities of modular configurations. In this paper, we develop a two-layered planning method for locomotion of a class of regular structures. This locomotion mode is based on multi-module blocks. The upper layer plans the overall cluster motion called flow to realize locomotion along a given desired trajectory; the lower layer determines locally cooperative module motions, called motion schemes, based on a rule database. A planning simulation demonstrates that this approach effectively solves the complicated planning problem. Besides the fundamental motion capacity of the module, the hardware feasibility of the planning locomotion is verified through a self-reconfiguration experiment using the prototype modules we have developed.

A Self-Reconfigurable Modular Robot: Reconfiguration Planning and Experiments

In this paper we address a reconfiguration planning method for locomotion of a homogeneous modular robotic system and we conduct an experiment to verify that the planned locomotion can be realized by hardware. Our recently developed module is self-reconfigurable. A group of the modules can thus generate various three-dimensional robotic structures and motions. Although the module itself is a simple mechanism, self-reconfiguration planning for locomotion presents a computationally difficult problem due to the many combinatorial possibilities of modular configurations. In this paper, we develop a two-layered planning method for locomotion of a class of regular structures. This locomotion mode is based on multi-module blocks. The upper layer plans the overall cluster motion called flow to realize locomotion along a given desired trajectory; the lower layer determines locally cooperative module motions, called motion schemes, based on a rule database. A planning simulation demonstrates that this approach effectively solves the complicated planning problem. Besides the fundamental motion capacity of the module, the hardware feasibility of the planning locomotion is verified through a self-reconfiguration experiment using the prototype modules we have developed.

Self-Excited Locomotion of a Snake Mechanism.

Snake-like animal locomotion by means of friction force can perform many kinds of motion and body shape. We have proposed the method of locomotion based on self-excitation principle in order to realize the high speed and high efficiency locomotion. In this study, we applied the self-excited locomotion to a snake mechanism. First we analyzed the kinematics and the dynamics of a three link snake mechanism driven by the self-excitation. Then we manufactured a prototype of a snake robot. By experimental identification of the traction parameters of the robot, we showed a good agreement between the experimental and simulated results and a high locomotion velocity of 0.4[m/s]. We further showed the high efficiency of the self-excited snake locomotion.

A new impact actuator using linear momentum exchange of inertia mass

For self-controlled endoscopes, many kinds of systems have been proposed. Among these, pneumatic actuators show significant potential. However, existing actuators, such as those used in endoscopes, have many weak points. In particular, free movement inside the human intestine is difficult because the diameter of the intestine varies dramatically along its length. We design and test a new method of locomotion of robotic endoscopes which allows safe manoeuverability in the human intestine. The actuating mechanism is composed of a solenoid at each end of the actuator and a single permanent magnet in the centre guide. If current is supplied to the two solenoids, attractive and repulsive forces occur between the permanent magnet and solenoid at each end. The permanent magnet moves by controlling the current supply period. When the current direction for operation is reversed, repulsive and attractive forces at each side are changed and the permanent magnet moves in the opposite direction. The collision at each period transfers momentum from the moving magnet to the actuator body. Furthermore, the moving speed of the actuator can be changed by the control of the impact force. Modelling and simulation are carried out to predict the performance of the actuator. The results of simulations are verified by comparison with experimental results. Finally, the momentum is measured by attaching an accelerometer to the solenoid head to define moving characteristics.

Aquatics, Flyers, Creepers and Terrestrials — students' conceptions of animal classification

There have been several investigations into students' conceptions of animal classification. Previous research has generally failed to study the criteria of classification used by the students. This study shows that students prefer to classify creatures along the criteria of habitat and locomotion (method of movement). They continue using these criteria even after learning the categories of biological taxonomy. The results lead to the assumption of an implicit theory of natural kinship of animals. The educational consequences for biology instruction, especially with regard to biological taxonomy, biodiversity, and evolution, are discussed.

Path Generation for Autonomous Locomotion of Articulated Steering Wheel Loader

A wheel loader is the major machine that has been used in several fields for scooping, carrying, and loading of crushed ores. Recently, automation of the wheel loader task has been receiving considerable attention. This article describes a path‐generation method for autonomous locomotion of the wheel loader. From the viewpoint of locomotion stability and ease of control, it is necessary for the path to be smooth and easily calculated. In order to satisfy these conditions, a path‐generation method using a clothoid curve is proposed. The change in curvature of the clothoid curve is continuous and is proportional to the length of the curve. Therefore, the clothoid curve provides continuous change of the steering angle. Furthermore, an interpolation method between the initial and target points of the wheel loader is proposed in this study, which consists of the clothoid curve segment and a straight‐line segment. A V‐shaped curve including the backward path and the forward path is also generated, taking into account the avoidance of rapid turning.

Intelligent Cruise-Control Navigation: A new navigation/travel method for use in virtual environments

An important feature of virtual reality is the facility for the user to move around a virtual environment in a natural and easily controlled manner. Navigation, also called locomotion, travel or motion, involves changing the perspective of the user in the virtual environment (VE). It allows the user to move in the VE as well as reorient themselves to look at the world differently. Natural locomotion methods are able to contribute to a sense of presence and reality. The illusion of presence can be lost through unnatural experiences during travel in the VE. This can be caused by poor interactive metaphors or by experiences which do not agree with the user's everyday understanding of the real world. This paper focuses on the navigation method in the VE, one of the major interfaces for the interactivity between human and VE in virtual reality circumstances and worlds. It proposes a new navigation method. Intelligent Cruise-Control Navigation (ICCN), which provides a natural and user-centred approach to navigation in the VE and can improve the user's sense of reality and presence. ICCN is composed of three major phases: Constant Velocity Navigation, Collision Detection and Avoidance, and Path Adjustment. The ICCN can reduce the user's fatigue and improve the user's presence in the VE. The small experimental study reported in this paper suggests that the ICCN will be a natural, straightforward, and useful navigation interface in VE.

Animal‐Inspired Sensing for Autonomously Climbing or Avoiding Obstacles

The way that natural systems navigate their environments with agility, intelligence and efficiency is an inspiration to engineers. Biological attributes such as modes of locomotion, sensory modalities, behaviours and physical appearance have been used as design goals. While methods of locomotion allow robots to move through their environment, the addition of sensing, perception and decision making are necessary to perform this task with autonomy. This paper contrasts how the addition of two separate sensing modalities – tactile antennae and non‐contact sensing – and a low‐computation, capable microcontroller allow a biologically abstracted mobile robot to make insect‐inspired decisions when encountering a shelflike obstacle, navigating a cluttered environment without collision and seeking vision‐based goals while avoiding obstacles.

Ontogenetic Effects on Locomotory Gaits in Nymphs of Baetis tricaudatus Dodds (Ephemeroptera:Baetidae)

The locomotory behavior of Baetis tricaudatus Dodds nymphs was examined by placing individuals of various lengths in a still-water tank and recording movement sequences using high-speed cinematography and video. Gait of small nymphs (≤3.0 mm) differed from that of larger nymphs (≥4.0 mm). Small nymphs combined dorso-ventral oscillations of the abdomen in addition to rowing with their legs, whereas large nymphs used only abdominal oscillations for propulsion. Transition from rowing to swimming gait occurred when the nymphs were ca 3.5 mm long, at Reynolds numbers of 60-90. When viscous forces predominate, friction-based methods of locomotion (i.e., rowing) are most efficient, whereas propulsive methods (i.e., abdominal undulations involving vortices--swimming) are more effective when inertial forces prevail. Small B. tricaudatus nymphs row because viscous forces do not allow propulsive mechanisms, and the use of leg orientation minimizes drag of the recovery stroke relative to that of the power stroke. Average speed increased linearly with body length in small nymphs, but exponentially in large nymphs. The shift from linear to exponential increase in speed occurred within the same range of body lengths as did change in gait. Ontogenic changes in gait and speed could be the mechanisms that regulate other size-dependent behaviors observed in Baetis spp., namely those involved with risk management and predator avoidance.

Development of Visually Guided Locomotion

This article presents a developmental account of changes in the visual guidance of locomotion. In contrast to the impressive efficiency of adult locomotion, locomotor activity is not under prospective control at the onset of human mobility. Infants require extensive crawling and walking experience before responding adaptively to variations in the terrain. At the same time that they are learning to navigate in increasingly varied environments, their bodies and skills are rapidly changing. Learning generalizes from safe, flat ground to novel surfaces but it does not transfer to new methods of locomotion. We account for these patterns of generality and specificity of learning by focusing on the role of exploratory behavior in detecting threats to balance control.

The mobility needs of women with physical disabilities in India: A functional perspective

The purpose of this research was to explore the functional mobility needs of women with lower extremity disabilities in Gujarat state, India. Ten women participated in a Mobility Needs Assessment which used multiple data collection methods to gather quantitative and qualitative information in five main areas. The results indicated that the physical environment was diverse, at times unpredictable, and environmental barriers were commonly encountered. The women travelled relatively long distances to perform self-care activities such as bathing and toileting. Furthermore, the women had compensated for their disability by implementing different strategies, such as four methods of locomotion, ten sitting positions, and various methods for carrying objects. Activities of daily living were similar amongst the women, although some women required assistance to complete specific activities successfully. Although the women expressed different views on how they felt about their present level of mobility, all were able to identify activities they wished to perform if they could move more easily. The resulting information contributed towards an area where little has been documented previously.

Locomotion in a Virtual Environment: Performance Measures and Physiological Responses

We are developing and studying a human-computer interface that allows a scientist to interact with complex software systems through immersive virtual reality technology. Virtual tools are being developed to empower the user to view, manipulate, model, diagnose, analyze, navigate through the software simulations and the multidimensional data it generates. For these tools to be truly effective, they must be evaluated in the context of human performance studies. This paper addresses one such category of tool: an efficient and natural means of locomotion in 3D virtual spaces. The current study is investigating three different methods of virtual body locomotion in the following context. Subjects were required to fly through a series of 3D tunnels while performance times and number of wall collisions were used as response measures. In addition, during each trial subjects were continuously monitored for physiological responses and psychological assessments were performed before and after the series of flights. This paper reports on the preliminary findings of the current study and the lessons learned in performing empirical studies on locomotion in virtual environments.