User:Alexander L. McQuiggan/sandbox

Undulatory Locomotion

Undulatory locomotion is a process of movement that can be described as alternating wavelength which propel an objects body in a given direction. A unique characteristic of the wave motion is that it is sinusoidal, or has equidistant positive and negative magnitudes throughout the length of a period. This allows for nice, even strokes that appear harmonious in nature when observed. Consider a sine graph, for example, the line moves evenly up and down from period to period without any disruption to an infinite length. With that in mind, think of the motion untilized by a snake, or that of the fins of a cuttlefish; the same pattern is followed, a constant wave both up and down, or side to side, that is even throughout a period of observation. Another exceptional aspect of undulatory motion is that it provides a means for balance and directional compensation as well as allowing for both frontward and backward movement. Take for example a cuttlefish, the animal utilizes such motion to allow for fast lateral movement as well as foreward and reverse directional movement. Also, it grants the species the unique ability to hover in any given location.

Existence in Nature

Undulatory locomotion proves most effective as a means of propulsion, and therefore it is not unexpected that it occures most commonly in organisms which exist in aquatic environments. The wave ocsilations push the water which allow for an exceptionally useful means of transportation. Undulatory locomotion, as it exists in underwater existing organisms equipped with fins, is broken into three different forms; rajiform, amiiform, and gymnotiform types. The rajiform type is fin propulsion that is generated by passing vertical undulations along pectoral fins. This form is the type of motion that is seen in stingrays, mantas, cuttlefish, as well as in the fins of squid. Amiiform locomotion is achieved through the use of a long-based dorsal fin that propels the object through the water while maintaining a straight body. Third, gymnotiform propulsion in almost opposite of amiiform locomotion as it employs the undulation of a long-based anal fin. A forth form exists in animals that use the motion in a full body application, for example eels or snakes. Such organisms employ a full body wave ocsilation from front to back which causes them to move in a motion that is commonly described as slithering.

Though the motions differ in appearence, some more than others, the motion is conceptually the same as it employs the same characteristics.

Robotic Application

Studies in the field of Biomimetics of undulatory locomotion as it exists in nature have led to the creation of robotic mechanisms which replicate the motion. Such robots intend to mimic the organisms and perform just as said organisms would when set in similar conditions. Therefore the robots have multiple nodes upon the axis of motion, meaning that if the robot were to have a fin which employs undulatory locomotion, that fin would need to be broken up into numerous sections. At each of these points, the motor would be required to move the band in both a positive and negative direction on a timed interval, all the while making sure that each node corresponds in perfect sync with every other node upon the same fin axis. This is an imperative attribute because if just one of the motors is off by any margin, the motion is compromised and the robot would not maintain an even pattern of locomotion.

A robot with multiple fins, replicating the body of an organism like a cuttlefish or ray, would require seperate motors per each fin. This is essential to replicate the motion due to the fact that if the fins were on the same motor, it would not permit the fins to move independently from one another. This would then not allow for lateral movement among the robot, and also would not equip the robot with the same balacing ability that is unique to squid, cuttlefish, and rays, and would not permit the robot to correct itself if thrown off course by any unforseen act.