Parallel manipulator usually more limited in the workspace; for instance, they generally cannot reach around obstacles. The calculations involved in performing a desired manipulation (forward kinematics) are also usually more difficult and can lead to multiple solutions. Two examples of popular parallel robots are the Stewart platform and the Delta robot. 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 movable base for devices such as flight simulators. This device is called a Stewart
38th parallel structures 38th parallel structures The 38th parallel structures, also known as the 38th parallel lineament, are a series of circular depressions or deformations stretching 700 km (435 mi) across southern Illinois and Missouri into eastern Kansas at a latitude of roughly 38 degrees north. Rampino and Volk (1996) postulated that these structures could be the remains of a serial meteorite strike in the late Mississippian or early Pennsylvanian periods. Difficulty in determining the age of many of the structures and doubts about the exogenic origins of several of them leave some geologists skeptical of this hypothesis. As of 2016, only two