Simulation of dual-stage soft landing

Hybrid model of dual-stage motion system, simulation of soft landing algorithm

Support data for an article "Dual-stage Soft Landing for a Pick-and-place Manipulator"

Abstract:

In this paper we document a systematic solution to a particular motion control
problem called soft landing. The task is to drive an end effector (tool) as fast as possible to
a physical contact with another object and exert a specified force on it. Neither during the
impact nor during the subsequent contact can the force exceed some given limits. The problem
is encountered when designing a motion control system for pick-and-place machines used in
semiconductor industry. The problem has already been studied in the literature for a single
actuator and a solution for the case of voice-coil motors has already been implemented in
commercial drivers. Here we investigate a more complex setup consisting of two translation
stages, which make the problem overactuated. Furthermore, the inner stage (actuated by the
voice coil motor) is preloaded with a weight-compansating spring. In this setup, the application
of existing techniques is not straightforward and a modification is needed. We present two
solution methods: one based on an intuitive extension of the existing soft landing approach, the
other based on the concept of reaction force observer. Numerical simulations and laboratory
experiments are documented. The reader can also download both Simulink model and Matlab
script to reproduce the design and the simulations.