Practical aspects of precision membrane antenna shape control

2009 International Conference on Mechatronics and Automation

2009

Maintenance of membrane structures geometry is crucial for them to be utilized in some space missions, including membrane antennae being developed at the Canadian Space Agency. In the harsh space environment, thermal loading and mechanical loading both can cause the distortion of membrane surfaces. Their effects on surface distortion will interact with each other. In order to properly design active control system, the interaction needs to be well characterized. An experimental setup is designed for this purpose. A square membrane is subjected to mechanical loading provided by comer tension forces and thermal loading provided by a ceramic heater. Surface profile of 7the membrane is measured using a photogrammetry system, which is based the out-of-plane sensitivity. In cases of symmetric thermal loading and asymmetric thermal loading, different mechanical loading cases are evaluated in terms of mitigating surface distortions. Some results are compared and explained using numerical results. Finally, the controllability of membrane structures is discussed using the results from these experiments. The conclusion has been applied to a larger membrane with multiple shape memory alloy actuators designed at the Canadian Space Agency.Index Terms -Membrane structures, active flatness control, shape memory alloy.

Section: Introductionmentioning

confidence: 99%

Experimental characterization for active flatness control of membrane structures

2009 International Conference on Mechatronics and Automation

2009

“…In the category of boundary control, Jenkins et al [12] first proposed spatially discretized mechanical "cells", each of which consisted of a spring, a mass and a damper, to actively maintain antenna flatness. Feedback error learning control was devised.…”

Section: Introductionmentioning

confidence: 99%

Thermo-mechanical analysis of thin membranes and application in active flatness control design

Sulik

Industrial and Commercial Applications of Smart Structures Technologies 2008

et al. 2008

Membrane structures are excellent candidates for many lightweight large space structures, which can be utilized to improve the performance and to reduce the cost of space exploration and earth observation missions. In-orbit thermal disturbance is the main cause of membrane wrinkling, which deteriorates membrane surface accuracy. In order to maintain surface accuracy in the time-varying environment, active flatness control is regarded as a very important technology. In order to properly design active flatness control system, understanding of the thermo-mechanical coupling and the effects of tensioning forces in reducing membrane wrinkling is required. Based on the von-Karman nonlinear plate theory, a theoretical framework is developed in this paper. An FE model for a square membrane is developed as an example for case studies. Using thin shell elements, this model is capable of predicting the amplitude of out-of-plane displacements. Using this model, the effect of thermal disturbance is studied, which qualitatively agrees with experimental observations. By varying corner loads in the numerical model, it is demonstrated that corner loads can efficiently reduce surface deviation caused by a center-located heat source. In order to study the effect of thermal disturbance locations, different temperature distributions are applied to the membrane. With these temperature distributions, different tension forces combinations are evaluated in terms of improving surface accuracy.

“…Using boundary control forces, Jenkins et al. [12] first proposed spatially discretized mechanical ‘cells’, each of which consists of a spring, a mass and a damper, to actively maintain antenna flatness. Feedback error learning control was devised.…”

Section: Introductionmentioning

confidence: 99%

An Experimental Study on the Interaction of Thermal Loading and Mechanical Loading in Membrane Structures

2011

Strain

Maintenance of membrane structures geometry is crucial for them to be utilised in some space missions, including membrane antennae being developed at the Canadian Space Agency. In the harsh space environment, thermal loading and mechanical loading both can cause the distortion of membrane surfaces. Their effects on surface distortion will interact with each other. In order to properly design active control system, the interaction needs to be well understood. An experimental setup is designed for this purpose. A square membrane is subjected to mechanical loading provided by corner tension forces and thermal loading provided by a ceramic heater. Surface profile of the membrane is measured using the photogrammetry technique. In cases of symmetric thermal loading and asymmetric thermal loading, different mechanical loading cases are evaluated in terms of mitigating surface distortions. Some results are compared and explained using numerical results. Finally, the controllability of membrane structures is discussed using the results from these experiments.