Hexapod (robotics)

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A six-legged walking robot should not be confused with a Stewart platform, a kind of parallel manipulator used in robotics applications.

Contents

Beetle hexapod Beetle robot.jpg
Beetle hexapod

A hexapod robot is a mechanical vehicle that walks on six legs. Since a robot can be statically stable on three or more legs, a hexapod robot has a great deal of flexibility in how it can move. If legs become disabled, the robot may still be able to walk. Furthermore, not all of the robot's legs are needed for stability; other legs are free to reach new foot placements or manipulate a payload.

Many hexapod robots are biologically inspired by Hexapoda locomotion – the insectoid robots. Hexapods may be used to test biological theories about insect locomotion, motor control, and neurobiology.

Designs

Two hexapod robots at the Georgia Institute of Technology with CMUCams mounted on top Hexapod robots.jpg
Two hexapod robots at the Georgia Institute of Technology with CMUCams mounted on top

Hexapod designs vary in leg arrangement. Insect-inspired robots are typically laterally symmetric, such as the RiSE robot at Carnegie Mellon. [1] A radially symmetric hexapod is ATHLETE (All-Terrain Hex-Legged Extra-Terrestrial Explorer) robot at JPL. [2]

Typically, individual legs range from two to six degrees of freedom. Hexapod feet are typically pointed, but can also be tipped with adhesive material to help climb walls or wheels so the robot can drive quickly when the ground is flat.

Locomotion

Walking hexapod simulated in Webots Hexapod webots.gif
Walking hexapod simulated in Webots

Most often, hexapods are controlled by gaits, which allow the robot to move forward, turn, and perhaps side-step. Some of the most common gaits are as follows:

Gaits for hexapods are often stable, even in slightly rocky and uneven terrain.

Motion may also be nongaited, which means the sequence of leg motions is not fixed, but rather chosen by the computer in response to the sensed environment. This may be most helpful in very rocky terrain, but existing techniques for motion planning are computationally expensive.

Biologically inspired

Insects are chosen as models because their nervous system are simpler than other animal species. Also, complex behaviours can be attributed to just a few neurons and the pathway between sensory input and motor output is relatively shorter. Insects' walking behaviour and neural architecture are used to improve robot locomotion. Conversely, biologists can use hexapod robots for testing different hypotheses.

Biologically inspired hexapod robots largely depend on the insect species used as a model. The cockroach and the stick insect are the two most commonly used insect species; both have been ethologically and neurophysiologically extensively studied. At present no complete nervous system is known, therefore, models usually combine different insect models, including those of other insects.

Insect gaits are usually obtained by two approaches: the centralized and the decentralized control architectures. Centralized controllers directly specify transitions of all legs, whereas in decentralized architectures, six nodes (legs) are connected in a parallel network; gaits arise by the interaction between neighbouring legs.

List of robots

See also

Related Research Articles

<span class="mw-page-title-main">Walking</span> Gait of locomotion among legged animals

Walking is one of the main gaits of terrestrial locomotion among legged animals. Walking is typically slower than running and other gaits. Walking is defined by an 'inverted pendulum' gait in which the body vaults over the stiff limb or limbs with each step. This applies regardless of the usable number of limbs—even arthropods, with six, eight, or more limbs, walk. In humans, walking has health benefits including improved mental health and reduced risk of cardiovascular disease and death.

<span class="mw-page-title-main">Gait</span> Pattern of movement of the limbs of animals

Gait is the pattern of movement of the limbs of animals, including humans, during locomotion over a solid substrate. Most animals use a variety of gaits, selecting gait based on speed, terrain, the need to maneuver, and energetic efficiency. Different animal species may use different gaits due to differences in anatomy that prevent use of certain gaits, or simply due to evolved innate preferences as a result of habitat differences. While various gaits are given specific names, the complexity of biological systems and interacting with the environment make these distinctions "fuzzy" at best. Gaits are typically classified according to footfall patterns, but recent studies often prefer definitions based on mechanics. The term typically does not refer to limb-based propulsion through fluid mediums such as water or air, but rather to propulsion across a solid substrate by generating reactive forces against it.

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<span class="mw-page-title-main">Snakebot</span> Snake-like robot

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Robot locomotion is the collective name for the various methods that robots use to transport themselves from place to place.

<span class="mw-page-title-main">Mobile robot</span> Type of robot

A mobile robot is an automatic machine that is capable of locomotion. Mobile robotics is usually considered to be a subfield of robotics and information engineering.

<span class="mw-page-title-main">Terrestrial locomotion</span> Ability of animals to travel on land

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<span class="mw-page-title-main">Tripedalism</span> Locomotion by use of three limbs

Tripedalism is locomotion by the use of three limbs. It has been said that parrots (Psittaciformes) display tripedalism during climbing gaits, which was tested and proven in a 2022 paper on the subject, making parrots the only creatures to truly use tripedal forms of locomotion. Tripedal gaits were also observed by K. Hunt in primates. This is usually observed when the animal is using one limb to grasp a carried object and is thus a non-standard gait. Apart from climbing in parrots, there are no known animal behaviours where the same three extremities are routinely used to contact environmental supports, although the movement of some macropods such as kangaroos, which can alternate between resting their weight on their muscular tails and their two hind legs and hop on all three, may be an example of tripedal locomotion in animals. There are also the tripod fish. Several species of these fish rest on the ocean bottom on two rays from their two pelvic fins and one ray from their caudal fin.

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<span class="mw-page-title-main">Legged robot</span> Type of mobile robot

Legged robots are a type of mobile robot which use articulated limbs, such as leg mechanisms, to provide locomotion. They are more versatile than wheeled robots and can traverse many different terrains, though these advantages require increased complexity and power consumption. Legged robots often imitate legged animals, such as humans or insects, in an example of biomimicry.

<span class="mw-page-title-main">Rhex</span>

RHex is an autonomous robot design, based on hexapod with compliant legs and one actuator per leg. A number of US universities have participated, with funding grants also coming from DARPA.

<span class="mw-page-title-main">Glossary of robotics</span> List of definitions of terms and concepts commonly used in the study of robotics

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<span class="mw-page-title-main">Robotics</span> Design, construction, use, and application of robots

Robotics is an interdisciplinary field that involves the design, construction, operation, and use of robots.

<span class="mw-page-title-main">Undulatory locomotion</span>

Undulatory locomotion is the type of motion characterized by wave-like movement patterns that act to propel an animal forward. Examples of this type of gait include crawling in snakes, or swimming in the lamprey. Although this is typically the type of gait utilized by limbless animals, some creatures with limbs, such as the salamander, forgo use of their legs in certain environments and exhibit undulatory locomotion. In robotics this movement strategy is studied in order to create novel robotic devices capable of traversing a variety of environments.

The following outline is provided as an overview of and topical guide to robotics:

<span class="mw-page-title-main">LAURON</span>

LAURON is a six-legged walking robot, which is being developed at the FZI Forschungszentrum Informatik in Germany. The mechanics and the movements of the robot are biologically-inspired, mimicking the stick insect Carausius Morosus. The development of the LAURON walking robot started with basic research in field of six-legged locomotion in the early 1990s and led to the first robot, called LAURON. In the year 1994, this robot was presented to public at the CeBIT in Hanover. This first LAURON generation was, in contrast to the current generation, controlled by an artificial neural network, hence the robot's German name: LAUfROboter Neuronal gesteuert. The current generation LARUON V was finished in 2013.

<span class="mw-page-title-main">Bio-inspired robotics</span>

Bio-inspired robotic locomotion is a fairly new subcategory of bio-inspired design. It is about learning concepts from nature and applying them to the design of real-world engineered systems. More specifically, this field is about making robots that are inspired by biological systems, including Biomimicry. Biomimicry is copying from nature while bio-inspired design is learning from nature and making a mechanism that is simpler and more effective than the system observed in nature. Biomimicry has led to the development of a different branch of robotics called soft robotics. The biological systems have been optimized for specific tasks according to their habitat. However, they are multifunctional and are not designed for only one specific functionality. Bio-inspired robotics is about studying biological systems, and looking for the mechanisms that may solve a problem in the engineering field. The designer should then try to simplify and enhance that mechanism for the specific task of interest. Bio-inspired roboticists are usually interested in biosensors, bioactuators, or biomaterials. Most of the robots have some type of locomotion system. Thus, in this article different modes of animal locomotion and few examples of the corresponding bio-inspired robots are introduced.

<span class="mw-page-title-main">Walking vehicle</span> Vehicles that use legs rather than wheels, wings or hulls, for land locomotion

A walking vehicle is a vehicle that moves on legs rather than wheels or tracks. Walking vehicles have been constructed with anywhere from one to more than eight legs. There are many designs for the leg mechanisms of walking machines that provide foot trajectories with different properties.

<span class="mw-page-title-main">Insectoid robot</span> Robot featuring some insect-like features

An insectoid robot is a, usually small, robot featuring some insect-like features. These can include the methods of locomotion, methods of navigation, and artificial intelligence based on insect models. Many of the problems faced by miniature robot designers have been solved by insect evolution. Researchers naturally look to insects for inspiration and solutions.

References

  1. "RiSE robot". Carnegie Mellon University.
  2. "ATHLETE". JPL. Archived from the original on 2006-09-29.