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Kinematic Pair
In classical mechanics, a kinematic pair is a connection between two physical objects that imposes constraints on their relative movement (kinematics). German engineer Franz Reuleaux introduced the kinematic pair as a new approach to the study of machines that provided an advance over the motion of elements consisting of simple machines. Description Kinematics is the branch of classical mechanics which describes the motion of points, bodies (objects) and systems of bodies (groups of objects) without consideration of the causes of motion. Kinematics as a field of study is often referred to as the "geometry of motion". For further detail, see Kinematics. Hartenberg & Denavit presents the definition of a kinematic pair: In the matter of connections between rigid bodies, Reuleaux recognized two kinds; he called them higher and lower pairs (of elements). With higher pairs, the two elements are in contact at a point or along a line, as in a ball bearing or disk cam and follower; t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Classical Mechanics
Classical mechanics is a physical theory describing the motion of macroscopic objects, from projectiles to parts of machinery, and astronomical objects, such as spacecraft, planets, stars, and galaxies. For objects governed by classical mechanics, if the present state is known, it is possible to predict how it will move in the future (determinism), and how it has moved in the past (reversibility). The earliest development of classical mechanics is often referred to as Newtonian mechanics. It consists of the physical concepts based on foundational works of Sir Isaac Newton, and the mathematical methods invented by Gottfried Wilhelm Leibniz, Joseph-Louis Lagrange, Leonhard Euler, and other contemporaries, in the 17th century to describe the motion of bodies under the influence of a system of forces. Later, more abstract methods were developed, leading to the reformulations of classical mechanics known as Lagrangian mechanics and Hamiltonian mechanics. These advance ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prismatic Joint
A prismatic joint is a one- degree-of-freedom kinematic pair which constrains the motion of two bodies to sliding along a common axis, without rotation; for this reason it is often called a slider (as in the slider-crank linkage) or a sliding pair. They are often utilized in hydraulic and pneumatic cylinders. A prismatic joint can be formed with a polygonal cross-section to resist rotation. See for example the dovetail joint and linear bearings. See also * Cylindrical joint * Degrees of freedom (mechanics) * Kinematic pair * Kinematics * Mechanical joint * Revolute joint A revolute joint (also called pin joint or hinge joint) is a one- degree-of-freedom kinematic pair used frequently in mechanisms and machines. The joint constrains the motion of two bodies to pure rotation along a common axis. The joint does ... References Kinematics Rigid bodies {{classicalmechanics-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SCARA Robot
The SCARA is a type of industrial robot. The acronym stands for Selective Compliance Assembly Robot Arm or Selective Compliance Articulated Robot Arm. By virtue of the SCARA's parallel-axis joint layout, the arm is slightly compliant in the X-Y direction but rigid in the Z direction, hence the term ''selective compliance''. This is advantageous for many types of assembly operations, for example, inserting a round pin in a round hole without binding. The second attribute of the SCARA is the jointed two-link arm layout similar to human arms, hence the often-used term, ''articulated''. This feature allows the arm to extend into confined areas and then retract or "fold up" out of the way. This is advantageous for transferring parts from one cell to another or for loading or unloading process stations that are enclosed. SCARAs are generally faster than comparable Cartesian robot systems. Their single pedestal mount requires a small footprint and provides an easy, unhindered form ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Serial Manipulator
Serial manipulators are the most common industrial robots and they are designed as a series of links connected by motor-actuated joints that extend from a base to an end-effector. Often they have an anthropomorphic arm structure described as having a "shoulder", an "elbow", and a "wrist". Serial robots usually have six joints, because it requires at least six degrees of freedom to place a manipulated object in an arbitrary position and orientation in the workspace of the robot. A popular application for serial robots in today's industry is the pick-and-place assembly line, assembly robot, called a SCARA robot, which has four degrees of freedom. Structure In its most general form, a serial robot consists of a number of rigid links connected with joints. Simplicity considerations in manufacturing and control have led to robots with only revolute joint, revolute or prismatic joints and orthogonal, parallel and/or intersecting joint axes (instead of arbitrarily placed joint ax ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pulley
A pulley is a wheel on an axle or shaft that is designed to support movement and change of direction of a taut cable or belt, or transfer of power between the shaft and cable or belt. In the case of a pulley supported by a frame or shell that does not transfer power to a shaft, but is used to guide the cable or exert a force, the supporting shell is called a block, and the pulley may be called a sheave. A pulley may have a groove or grooves between flanges around its circumference to locate the cable or belt. The drive element of a pulley system can be a rope, cable, belt, or chain. The earliest evidence of pulleys dates back to Ancient Egypt in the Twelfth Dynasty (1991-1802 BCE) and Mesopotamia in the early 2nd millennium BCE. In Roman Egypt, Hero of Alexandria (c. 10-70 CE) identified the pulley as one of six simple machines used to lift weights. Pulleys are assembled to form a block and tackle in order to provide mechanical advantage to apply large forces. Pulleys ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mechanical Advantage
Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. The device trades off input forces against movement to obtain a desired amplification in the output force. The model for this is the ''law of the lever.'' Machine components designed to manage forces and movement in this way are called mechanisms. An ideal mechanism transmits power without adding to or subtracting from it. This means the ideal machine does not include a power source, is frictionless, and is constructed from rigid bodies that do not deflect or wear. The performance of a real system relative to this ideal is expressed in terms of efficiency factors that take into account departures from the ideal. Lever The lever is a movable bar that pivots on a fulcrum attached to or positioned on or across a fixed point. The lever operates by applying forces at different distances from the fulcrum, or pivot. The location of the fulcrum determi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Belt (mechanical)
A belt is a loop of flexible material used to link two or more rotating shafts mechanically, most often parallel. Belts may be used as a source of motion, to transmit power efficiently or to track relative movement. Belts are looped over pulleys and may have a twist between the pulleys, and the shafts need not be parallel. In a two pulley system, the belt can either drive the pulleys normally in one direction (the same if on parallel shafts), or the belt may be crossed, so that the direction of the driven shaft is reversed (the opposite direction to the driver if on parallel shafts). The belt drive can also be used to change the speed of rotation, either up or down, by using different sized pulleys. As a source of motion, a conveyor belt is one application where the belt is adapted to carry a load continuously between two points. History The mechanical belt drive, using a pulley machine, was first mentioned in the text the ''Dictionary of Local Expressions'' by the Han Dynasty ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gear
A gear is a rotating circular machine part having cut teeth or, in the case of a cogwheel or gearwheel, inserted teeth (called ''cogs''), which mesh with another (compatible) toothed part to transmit (convert) torque and speed. The basic principle behind the operation of gears is analogous to the basic principle of levers. A gear may also be known informally as a cog. Geared devices can change the speed, torque, and direction of a power source. Gears of different sizes produce a change in torque, creating a mechanical advantage, through their ''gear ratio'', and thus may be considered a simple machine. The rotational speeds, and the torques, of two meshing gears differ in proportion to their diameters. The teeth on the two meshing gears all have the same shape. Two or more meshing gears, working in a sequence, are called a gear train or a '' transmission''. The gears in a transmission are analogous to the wheels in a crossed, belt pulley system. An advantage of gears is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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__NOTOC__ Year 611 ( DCXI) was a common year starting on Friday (link will display the full calendar) of the Julian calendar. The denomination 611 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years. Events By place Persian Empire * Byzantine–Persian War: The Persian army under Shahrbaraz captures Antioch, and most of the remaining Byzantine fortresses in Syria and Mesopotamia. King Khosrau II is re-establishing a neo- Persian Empire, and intensifies his war effort. The Byzantine army, ruined by defeat and corruption, offers only half-hearted opposition. Britain * Cynegils becomes king of the West Saxons, or Wessex, after the death of his uncle Ceolwulf (according to the '' Anglo-Saxon Chronicle''). He rules from 611 to 643 and shares power to some extent with his eldest son, Cwichelm, who may have been given Upper Wessex (approximate date). By topic Relig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planar Joint
A plane joint (arthrodial joint, gliding joint, plane articulation) is a synovial joint which, under physiological conditions, allows only gliding movement. Plane joints permit sliding movements in the plane of articular surfaces. The opposed surfaces of the bones are flat or almost flat, with movement limited by their tight joint capsules. Plane joints are numerous and are nearly always small, such as the acromioclavicular joint between the acromion of the scapula and the clavicle. Typically, they are found in the wrists, ankles, the 2nd through 7th sternocostal joints, vertebral transverse and spinous process The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...es.Moore, et al. ''Introduction to Clinically Oriented Anatomy''. Baltimore: Lippincott Williams & Wilkins, 2006. Refer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ball And Socket Joint
The ball-and-socket joint (or spheroid joint) is a type of synovial joint in which the ball-shaped surface of one rounded bone fits into the cup-like depression of another bone. The distal bone is capable of motion around an indefinite number of axes, which have one common center. This enables the joint to move in many directions. An enarthrosis is a special kind of spheroidal joint in which the socket covers the sphere beyond its equator.Platzer, Werner (2008) ''Color Atlas of Human Anatomy'', Volume 1p.28/ref> Examples Examples of this form of articulation are found in the hip, where the round head of the femur (ball) rests in the cup-like acetabulum The acetabulum (), also called the cotyloid cavity, is a concave surface of the pelvis. The head of the femur meets with the pelvis at the acetabulum, forming the hip joint. Structure There are three bones of the ''os coxae'' (hip bone) that c ... (socket) of the pelvis; and in the shoulder joint, where the rounded upp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spherical Joint
In an automobile, ball joints are spherical bearings that connect the control arms to the steering knuckles, and are used on virtually every automobile made. They bionically resemble the ball-and-socket joints found in most tetrapod animals. A ball joint consists of a bearing stud and socket enclosed in a casing; all these parts are made of steel. The bearing stud is tapered and threaded, and fits into a tapered hole in the steering knuckle. A protective encasing prevents dirt from getting into the joint assembly. Usually, this is a rubber-like boot that allows movement and expansion of lubricant. Motion-control ball joints tend to be retained with an internal spring, which helps to prevent vibration problems in the linkage. The "offset" ball joint provides means of movement in systems where thermal expansion and contraction, shock, seismic motion, and torsional motions, and forces are present. Theory A ball joint is used for allowing free rotation in two planes at th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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