Hexapod (other)
Hexapod may refer to: Things with six limbs, e.g. a hexapod chair would have six not the traditional four limbs Biology * Hexapoda, a subphylum of arthropods including the insects * Hexapodidae, a family of crabs Technology * Hexapod (robotics), a mechanical vehicle that walks on six legs * Stewart platform, a machine platform supported by six struts, used in robotics * Hexapod-Telescope, a telescope in Chile mounted on a Stewart platform chassis frame See also * Tetrapod * Octopod An octopus ( : octopuses or octopodes, see below for variants) is a soft-bodied, eight- limbed mollusc of the order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttl ...

Hexapoda
The subphylum Hexapoda (from Greek for 'six legs') comprises most species of arthropods and includes the insects as well as three much smaller groups of wingless arthropods: Collembola, Protura, and Diplura (all of these were once considered insects). The Collembola (or springtails) are very abundant in terrestrial environments. ''Hexapods'' are named for their most distinctive feature: a consolidated thorax with three pairs of legs (six legs). Most other arthropods have more than three pairs of legs. Most recent studies have recovered Hexapoda as a subgroup of Crustacea. Morphology Hexapods have bodies ranging in length from 0.5 mm to over 300 mm which are divided into an anterior head, thorax, and posterior abdomen. The head is composed of a presegmental ''acron'' that usually bears eyes (absent in Protura and Diplura), followed by six segments, all closely fused together, with the following appendages: :Segment I. None :Segment II. Antennae (sensory), absent in Pr ...
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Hexapodidae
Hexapodidae is a family of crabs, the only family in the superfamily Hexapodoidea. It has traditionally been treated as a subfamily of the family Goneplacidae, and was originally described as a subfamily of Pinnotheridae. Its members can be distinguished from all other true crabs by the reduction of the thorax, such that only seven sternites are exposed, and only four pairs of pereiopods are present. Not counting the enlarged pair of claws, this leaves only six walking legs, from which the type genus ''Hexapus'', and therefore the whole family, takes its name. Some anomuran "crabs", such as porcelain crabs and king crabs also have only four visible pairs of legs. With the exception of '' Stevea williamsi'', from Mexico, all the extant members are found either in the Indo-Pacific oceans, or around the coast of Africa. Fossil record In addition to the extant taxa, the family contains two genera known only from fossils – '' Goniocypoda'' and '' Palaeopinnixa'' – and two furth ...
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Hexapod (robotics)
''A six-legged walking robot should not be confused with a Stewart platform, a kind of parallel manipulator used in robotics applications''. 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 Hexapod designs vary in leg arrangement. Insect-inspired robots are typically laterally symmetric, such as the RiSE robot at Carnegie Mellon. A radially symmetric hexapod is ATHLETE (All-Terrain Hex-Legged Extra-Terrestrial Explorer) ro ...
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Stewart Platform
A Stewart platform is a type of parallel manipulator that has six prismatic actuators, commonly hydraulic jacks or electric linear actuators, attached in pairs to three positions on the platform's baseplate, crossing over to three mounting points on a top plate. All 12 connections are made via universal joints. Devices placed on the top plate can be moved in the six degrees of freedom in which it is possible for a freely-suspended body to move: three linear movements x, y, z (lateral, longitudinal, and vertical), and the three rotations (pitch, roll, and yaw). Stewart platforms are known by various other names. In many applications, including in flight simulators, it is commonly referred to as a motion base. It is sometimes called a ''six-axis platform'' or ''6-DoF platform'' because of its possible motions and, because the motions are produced by a combination of movements of multiple actuators, it may be referred to as a ''synergistic motion platform'', due to the synergy (m ...
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Hexapod-Telescope
The Hexapod-Telescope (HPT) is a telescope located at Cerro Armazones Observatory in northern Chile. The Ritchey-Chrétien reflecting telescope is notable for the design of the telescope mount. Instead of the typical mounting where the telescope moves on two rotating axes, the mirror end of the telescope is supported by six extensible struts, an arrangement known as a Stewart platform. This configuration allows the telescope to move in all six spatial degrees of freedom and also provides strong structural integrity. As a result, the ratio of bearing pressure and its own weight is very high. Furthermore, the six-leg structure allows for a very precise positioning and repeatability. The disadvantage of the system is that controlling and aiming a hexapod-mounted telescope is much more complex than with conventional telescope mounts. The mounting was designed by engineers of the company Vertex, in collaboration with astronomers of the Astronomy Institute of the Ruhr University B ...
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Tetrapod
Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids ( reptiles, including dinosaurs and therefore birds) and synapsids (pelycosaurs, extinct therapsids and all extant mammals). Tetrapods evolved from a clade of primitive semiaquatic animals known as the Tetrapodomorpha which, in turn, evolved from ancient lobe-finned fish (sarcopterygians) around 390 million years ago in the Middle Devonian period; their forms were transitional between lobe-finned fishes and true four-limbed tetrapods. Limbed vertebrates (tetrapods in the broad sense of the word) are first known from Middle Devonian trackways, and body fossils became common near the end of the Late Devonian but these were all aquatic. The first crown-tetrapods (last common ancestors of extant tetrapods capable of terrestrial locomotion) appeared by the very early Carboniferous, 350 million years ago. The specific aquatic ancestors ...
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