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.

Parallel robots lead to complex kinematics equations, so determination of their workspaces is a challenging issue. The workspace of a robot is not fully characterized by its volume alone; the workspace shape is an important aspect as well. In this paper, the geometric determination of the workspace for Delta robots is presented. The workspace (workspace volume and workspace shape) for the robots is studied systematically in 'the physical model of the solution space', which is a useful tool to express relationships between the performance criteria and all link lengths of one type of robotic mechanism. Performance atlases of the workspace volume for the robots are plotted in the physical model of the solution space. The characteristics of the distribution of the workspace shapes in the physical model of the solution space are presented as well. The physical model of the solution space presents a new method for the computer aided design (CAD) of robotic mechanisms. The results are very useful for obtaining the optimum design of robotic mechanisms.

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.