''A six-legged walking robot should not be confused with a

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 po ...

, a kind of

parallel manipulator A parallel manipulator is a mechanical system that uses several computer-controlled serial chains to support a single platform, or end-effector. Perhaps, the best known parallel manipulator is formed from six linear actuators that support a mova ...

used in robotics applications''. Beetle robot

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 robot An insectoid robot is a, usually small, robot featuring some insect-like features. These can include the methods of locomotion (including flying), methods of navigation, and artificial intelligence based on insect models. Many of the problems f ...

s. 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) robot at

JPL The Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center in the City of La Cañada Flintridge, California, United States. Founded in the 1930s by Caltech researchers, JPL is owned by NASA an ...

. Typically, individual legs range from two to six

degrees of freedom Degrees of freedom (often abbreviated df or DOF) refers to the number of independent variables or parameters of a thermodynamic system. In various scientific fields, the word "freedom" is used to describe the limits to which physical movement or ...

. 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

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: * Alternating tripod: 3 legs on the ground at a time. * Quadruped. * Crawl: move just one leg at a time. 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 A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. N ...

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 The Phasmatodea (also known as Phasmida, Phasmatoptera or Spectra) are an order of insects whose members are variously known as stick insects, stick-bugs, walking sticks, stick animals, or bug sticks. They are also occasionally referred to as ...

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

* Hexbug (insectoid toy robot) *

Stiquito Stiquito (pronounced sti ke to) is a small, inexpensive hexapod (i.e., six-legged) robot commonly used by universities, high schools, and hobbyists, since 1992. Stiquito's "muscles" are made of nitinol, a shape memory alloy that expands and co ...

(inexpensive

) *

Rhex 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. Versions have shown good mobility over a wide range o ...

Whegs Whegs (''wheel-legs or wing-legs'') are mechanisms for robot locomotion. Whegs use a strategy of locomotion that combines the simplicity of the wheel with the obstacle-clearing advantages of the foot. Whegs were pioneered at the Biologically In ...

LAURON 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 developme ...

References

External links