Gantry-Tau – A New Three Degrees of Freedom Parallel Kinematic Robot

In the last decades, an increasing attention has been paid to the study of different parallel structure mechanisms and their applications, mainly triggered by Stewart that presented an aircraft simulator system. Parallel structure features provide big advantages in potential applications. For example, parallel robots may give higher speed and acceleration, higher static and dynamic accuracy and higher stiffness than what is possible with the industrial robots used today. A typical limitation with many of the paral-lel structures is that their workspace is small com-pared to the serial structures. This paper presents a new parallel structure, the Gantry-Tau, which pro-vides 3 degrees of freedom (DOF) translational mo-tion with a large workspace. The structure of the ro-bot is patented by ABB. The Gantry-Tau robot is a six link parallel kinematic structure with the links configured according to 3-2-1. The 3-2-1 notation refers to how many links form each resulting kine-matic cluster of the robot. Orientational DOF of the robot could be provided by a decoupled system. For a conventional 3 DOF serial gantry ro-bot two of the actuators contribute to the moving mass. The Gantry-Tau can be constructed with ex-ceptionally low moving mass since the actuators are stationary and the structure has inherently high stiff-ness. The structure is thus ideal for many applications with demands on high accelerations, for instance for the pick and place operations. The nominal inverse and direct kinematics of the structure are developed and optimization is used to find a construction of Gantry-Tau with maximum workspace volume