Positioning Repeatability of Robotic Systems With Synchronous Belt Drives

Substrate-handling robots for pick-place operations in semiconductor manufacturing applications are subject to strict substrate placement repeatability specifications. It has been observed that the placement locations at a given workstation tend to exhibit distinct clusters, each of which can be associated with another workstation accessed by the robot in the past, resulting in an undesirable increase of the overall placement repeatability range. In the present paper, this memory-like repeatability phenomenon is studied, and attributed to multistage synchronous belt drives, which are utilized to transmit motion from centralized motors to individual links and end-effectors of the robot arms. The phenomenon is investigated experimentally, and simulated using a simplified lump-parameter model. The effects of selected belt drive design parameters are examined, and the results are utilized to improve the positioning repeatability performance of a typical substrate-handling robot.

Droplet-Resolved Dilute Spray Evaporation Model

A numerical model that enables the simulation of polydispersed spray behavior while allowing the resolution of droplet-scale features is described. This Lagrangian model is based on a sectional approach and captures the effect of polydispersity, droplet initial speed and direction. It is designed for flexibility in that it can be used for a variety of droplet-based processes. The model performance is illustrated using two basic configurations: spray combustion and water mist fire suppression. The spray combustion case shows how the droplet-scale resolution can be critical since phase equilibrium is controlled by droplet surface temperature, which cannot be adequately captured using a lump-parameter model. The water mist case allows a demonstration of the basic features of the spray model such as the ability to characterize the ability of smaller droplets to get close enough to a fire or a hot surface.

Vibration of Satellite Subsystem During Orbiter Lift-Off

Vibrations of a satellite and one of its sensitive subsystems during orbiter lift-off are studied. A single degree-of-freedom representation of the subsystem and a five degree-of-freedom lump parameter model of the satellite are considered. Deflection and acceleration response spectra of the satellite and its subsystem subject to sinusoidal excitation and the STS - 41 lift-off accelerations are evaluated. The significance of the subsystem and primary satellite interaction is investigated. The effect of mass ratio and damping coeficient of the subsystem on the peak deflection and acceleration response spectra of the satellite and its subsystem are examined.