An active vertical-direction gravity compensation system

Author

White, Gregory C. ; Xu, Yangsheng

Author_Institution

Robotics Inst., Carnegie Mellon Univ., Pittsburgh, PA, USA

Volume

43

Issue

6

fYear

1994

fDate

12/1/1994 12:00:00 AM

Firstpage

786

Lastpage

792

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;

fLanguage

English

Journal_Title

Instrumentation and Measurement, IEEE Transactions on

Publisher

ieee

ISSN

0018-9456

Type

jour

DOI

10.1109/19.368066

Filename

368066