The Kinematic Design of the Parallel Motion Simulator With Spherical-Translation Movement

Abstract

A motion simulator is a type of equipment which can reproduce the actual movement environment for an object. It can be widely used in various occasions. Current motion simulator mainly utilizes the full degree-of-freedom (DOF) parallel mechanisms (PMs), such as the Stewart platform, as the main body of the machine. In fact, there is no need to use the full-DOF mechanism at the most of the time. Some deficient-DOF mechanisms can also meet the demands of certain motion simulation. Especially for some predefined motion patterns, the dedicated equipment is more capable and convenient to use than the universal one. In this paper, a practical types of motion simulators for testing the performance under the spherical-translation motion is presented. Specifically, the orientation of the tested object remains fixed during the whole process in order to fulfill the certain simulation demand. First of all, the motion and constraint characteristics for the spherical-translation movement are brought forward using a graphical approach. Based on these conditions, a typical parallel mechanism 3-UU with desired motion pattern is taken out in further to verify the constraint conditions above. Besides, the architecture of each limb is analyzed to observe the necessary condition that the structure characteristics should satisfy. Furthermore, its functional limitation in simulating the spherical-translation motion in random direction is also proposed. According to all the architecture features retained by the mechanism, the new types of motion simulator outputting the desired movement is synthesized and designed at the last, which has been categorized for different application fields.