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Serial manipulators are the most common industrial robots. 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 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 or prismatic joints and orthogonal, parallel and/or intersecting joint axes (instead of arbitrarily placed joint axes). Donald L. Pieper derived the first practically relevant result in this context,〔D.L. Pieper. The kinematics of manipulators under computer control. PhD Thesis, Stanford University, Department of Mechanical Engineering, 1968〕 referred to as 321 kinematic structure: ''The inverse kinematics of serial manipulators with six revolute joints, and with three consecutive joints intersecting, can be solved in closed-form, i.e. analytically'' This result had a tremendous influence on the design of industrial robots. The main advantage of a serial manipulator is a large workspace with respect to the size of the robot and the floor space it occupies. The main disadvantages of these robots are: * the low stiffness inherent to an open kinematic structure, * errors are accumulated and amplified from link to link, * the fact that they have to carry and move the large weight of most of the actuators, and * the relatively low effective load that they can manipulate. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Serial manipulator」の詳細全文を読む スポンサード リンク
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