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 mote complex parallel manipulators have led to more interest in parallel manipulators with less than six degrees of freedom (Dots). 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

In this paper, a new design method considering a desired workspace and swing range of spherical joints of a DELTA robot is presented. The design is based on a new concept, which is the maximum inscribed workspace proposed in this paper. Firstly, the geometric description of the workspace for a DELTA robot is discussed, especially, the concept of the maximum inscribed workspace for the robot is proposed. The inscribed radius of the workspace on a workspace section is illustrated. As an applying example, a design result of the DELTA robot with a given workspace is presented and the reasonability is checked with the conditioning index. The results of the paper are very useful for the design and application of the parallel robot.

In this paper, a new spatial three-degrees-of-freedom (two degrees of translational freedom and one degree of rotational freedom) parallel manipulator is proposed. The parallel manipulator consists of a base plate, a movable platform, and three connecting legs. The inverse and forward kinematics problems are described in closed forms and the velocity equation of the new parallel manipulator is given. Three kinds of singularities are also presented. The workspace for the manipulator is analyzed systematically; in particular, indices to evaluate the mobility (in this paper, mobility means rotational capability) of the moving platform of the manipulator will be defined and discussed in detail. Finally, a topology architecture of the manipulator is introduced. The parallel manipulator has wide application in the fields of industrial robots, simulators, micromanipulators, and parallel machine tools.

A parallelogram allows the output link to remain at a fixed orientation with respect to an input link, for which it acts as a unique role in the design of parallel mechanisms. In this paper, the unique role of a parallelogram is used completely to design some new parallel mechanisms with two to six degrees of freedom (DoFs). In these mechanisms, some with three DoFs possess the advantage of very high rotational capability and some with two DoFs have the translational output of a rigid body. More than that, the design concept is also applied first to some parallel mechanisms to improve the systems' rotational capability. The parallel mechanisms proposed in this paper have wide applications in industrial robots, simulators, micromanipulators, parallel kinematics machines, and any other manipulation devices in which high rotational capability and stiffness are needed. Especially, the paper provides new concepts of the design of novel parallel mechanisms and the improvement of rotational capability for such systems.

Most fully-parallel manipulators encountered today have a common disadvantage, i.e., their low rotational capability. To overcome such a difficulty, this paper focuses its attention on the proposal of a new family of three-degree-of-freedom (3-DoF) fully-parallel manipulators capable of high rotational capability. Parallelogram allows the output link to remain at a fixed orientation with respect to an input link, for which it has many unique roles, especially when creating a desirable DoF output in the design of parallel manipulators. The role of a parallelogram herein described, is used completely for the design of a new parallel manipulator family. In this family, the moving platform of a parallel manipulator is connected to the base by three non-identical legs. The fact that all joints involved in the rotational DoF are with single DoF guarantees the high rotational capability performance of the manipulators. The parallel manipulators proposed here have wide applications in industrial robots, simulators, micro-motion manipulators, parallel kinematics machines, and any other manipulation devices that a high rotational capability is needed. The research provides a new design methodology of novel parallel manipulators. 2004 Elsevier Ltd. All rights reserved.