Title :
An active vertical-direction gravity compensation system
Author :
White, Gregory C. ; Xu, Yangsheng
Author_Institution :
Robotics Inst., Carnegie Mellon Univ., Pittsburgh, PA, USA
fDate :
12/1/1994 12:00:00 AM
Abstract :
To perform simulations of partial or microgravity environments on Earth requires some method of compensation for the Earth´s gravitational field. This paper discusses an active compensation system that modulates the tension in a counterweight support cable in order to minimize state deviation between the compensated body and the ideal weightless body. The system effectively compensates for inertial effects of the counterweight mass, viscous damping of all pulleys, and static friction in all parts of the gravity compensation (GC) system using a hybrid PI (proportional plus integral)/fuzzy control algorithm. The dynamic compensation of inertia and viscous damping is performed by PI control, while static friction compensation is performed by the fuzzy system. The system provides a very precise gravity compensation force, and is capable of nonconstant gravity force compensation in the case that the payload mass is not constant
Keywords :
aerospace control; compensation; control system synthesis; fuzzy control; gravity; robots; two-term control; vibration control; zero gravity experiments; active compensation; active vertical-direction gravity compensation; counterweight mass; counterweight support cable; dynamic compensation; hybrid PI fuzzy control algorithm; inertial effects; microgravity environments; simulations; state deviation; static friction compensation; viscous damping; Damping; Friction; Gravity; Mechanical cables; Mobile robots; Motor drives; Payloads; Pulleys; Robot sensing systems; Underwater cables;
Journal_Title :
Instrumentation and Measurement, IEEE Transactions on