High performance positioning system

A high performance positioning system (HPPS) is a type of positioning system consisting of a piece of electromechanics equipment (e.g. an assembly of linear stages and rotary stages) that is capable of moving an object in a three-dimensional space within a work envelope. Positioning could be done point to point or along a desired path of motion. Position is typically defined in six degrees of freedom, including linear, in an x,y,z cartesian coordinate system, and angular orientation of yaw, pitch, roll. HPPS are used in many manufacturing processes to move an object (tool or part) smoothly and accurately in six degrees of freedom, along a desired path, at a desired orientation, with high acceleration, high deceleration, high velocity and low settling time. It is designed to quickly stop its motion and accurately place the moving object at its desired final position and orientation with minimal jittering.

HPPS requires a structural characteristics of low moving mass and high stiffness. The resulting system characteristic is a high value for the lowest natural frequency of the system. High natural frequency allows the motion controller to drive the system at high servo bandwidth, which means that the HPPS can reject all motion disturbing frequencies, which act at a lower frequency than the bandwidth. For higher frequency disturbances such as floor vibration, acoustic noise, motor cogging, bearing jitter and cable carrier rattling, HPPS may employ structural composite materials for damping and isolation mounts for vibration attenuation. Unlike articulating robots, which have revolute joints that connect their links, HPPS links typically consists of sliding joints, which are relatively stiffer than revolute joints. That is the reason why high performance positioning systems are often referred to as cartesian robots.