外文翻译--具有2或3个自由度的对应机械手.doc

Parallel Mechanisms with Two or Three Degrees of Freedom Christiaan J.J. Paredis, H. Benjamin Brown, Pradeep K. Khosla Abstract: Parallel manipulators for the machine tool Industry have been studied extensively for various industrial applications. However, limited useful workspace areas, the poor mobility, and design difficulties of more complex parallel manipulators have led to mare interest in parallel manipulators with less than six degrees of freedom (DoFs). Several parallel mechanisms with various numbers and types of degrees of freedom are described in this paper, which can be used in parallel kinematics machines, motion simulators, and industrial robots. Key words: parallel manipulator; parallel kinematic machine; degree of freedom; robot Introduction Mechanical systems that allow a rigid body to move with respect to a fixed base play a very important role in numerous applications. A rigid body can move in various translational or rotational directions which are called degrees of freedom (DoFs). The total number of degrees of freedom for a rigid body cannot exceed six, for example, three axes, A robot includes a system to control several degrees of freedom of an end – effector. The last few years have witnessed important developments in the use of industrial robots, mainly due to their flexibility. However, the mechanical architecture of the most common robots is not well adapted to certain tasks. Other types of architectures have, therefore, recently been developed for industrial use, including parallel manipulators. A parallel manipulator, which is a closed-loop mechanism, typically consists of a moving platform that is connected to a fixed base by several limbs or legs. Typically, the number of limbs is equal to the number of degrees of freedom such that every limb is controlled by one actuator and all the actuators can be mounted at or near the fixed base. For this reason, parallel manipulators. Because the external load can be shared by the actuators