A Prototype of a Controllable Hinge Mechanism Used For The Deployment of a SAR Membrane-Antenna

Paper number

IAC-07-C2.2.03

Author

Ms. Véronique Tokateloff, Royal Military College of Canada, Canada

Coauthor

Prof. Georges Akhras, Canada

Coauthor

Dr. Marie-José Potvin, Canadian Space Agency, Canada

Coauthor

Mr. Steeve Montminy, Canadian Space Agency, Canada

Coauthor

Dr. Yu Shen, Canadian Space Agency, Canada

Year

2007

Abstract

An ongoing challenge in the aerospace industry is to implement novel ways in reducing the overall weight and complexity of a system so that significant cost savings ensue. For space-bound projects such as satellites, deployable structures can combine low mass and volume, thus allowing the use of a smaller less expensive launcher. The design of lightweight robust controllable hinges for these structures is consequently very desirable.   

   In this project, a deployment mechanism for a high packaging efficiency satellite SAR (synthetic aperture radar) membrane antenna is developed. The device should be compact, space qualified, lightweight and be able to actuate the complete deployment of a large antenna wing from its initial stowed state to its final functional shape. 

   Based on earlier work in the field, a Tape Spring Rolamite Hinge (TSR) is proposed. The TSR exploits the stored elastic energy of curved spring steel strips placed in a way such that the hinge self-deploys and self-locks into a final stiff straight configuration. When compared with the motor alternative, a controlled TSR is a space-suitable choice due to its relative simplicity, low part count and equivalent power requirements. 

   If unrestrained, the former hinge deployment motion can be swift and produce large snap-through shock and backlash as the tape spring attempts to lock into the desired configuration.  This initial design was modified to minimize the dynamic disturbances that would be transferred to the spacecraft. The new modified hinge is composed of two tape springs, two motion guide wheels and pins, a motion control mechanism and a shape memory alloy (SMA) actuator. The deployment control mechanism was inspired by a conventional clock escapement mechanism, such that the one-degree-of-freedom hinge deploys as the needles of a clock would unwind. Moreover, instead of using a more traditional rotary motor approach to actuate this control motion, SMAs are used to control the unwinding speed of the tape springs. The use of SMAs greatly reduces the complexity of the setup and the number of parts, thus increasing the hinge's robustness.

   This paper presents the new hinge design.  The experimental program is explained as are the challenges encountered during the manufacturing and testing phases. The analytical results of the moment-rotation relationship of the tape springs are compared with the experimental results. The SMA motion-control mechanism repeatability is also discussed. Finally, recommendations for future work are suggested to further improve the prototype's overall functionality.

Abstract document

IAC-07-C2.2.03.pdf

Manuscript document

IAC-07-C2.2.03.pdf (🔒 authorized access only).

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