M. Asgari - Dept. of Mechatronics Engineering, College of Electrical Engineering, Islamic Azad University, Qazvin Branch, Qazvin, Iran
H. Sadjadian - Dept. of Electrical Engineering, Iran University of Science and Technology, Tehran, Iran
Mahdi. A. Ardestani - Iran Transmission Research Center, Tehran, Iran

Parallel robots are used in Machining, Welding, Quality control, Flying simulator and other similar applications, because of their high precision in positioning. In this paper, new structure of spatial parallel robots from DELTA robots family, that is named MODIFIED DELTA robot, is presented. The proposed mechanism has two plates, one fixed and another moving on top and below respectively. The moving platform is the robot’s end-effector, that it has three degrees of pure translational freedom. At first, the geometry of robot is described and closed form equations of robot’s kinematics model are developed. Then, the closed form results are verified, that indicates validity of the exploited model. Finally, workspace of the manipulator is demonstrated graphically. The position of three active joints relative to each other is the main difference between this mechanism and DELTA mechanism, which has caused change in geometry of platforms. And it shapes the asymmetrical structure in the robot mechanism and its workspace. This asymmetrical structure provides new capabilities in the machining because of its special workspace. Moreover it can be used for studying in tip-over stability of hybrid serial-parallel mobile robotic systems, for heavy object manipulation applications.

Parallel manipulators; Kinematic modeling; Workspace analysis; Pure translation