Enhanced Linear Fractional Transformation: a Matlab Toolbox for Space System Modeling and Controller Analysis and Synthesis

Through an example of orbital rendezvous between a flexible spacecraft and a rigid target, this paper presents the Enhanced Linear Fractional Transformation Toolbox (ELFTT) developed under ESA contract in order to support advanced design, validation and verification processes of space system control loop. ELFTT will be distributed within the ESA Member States under an Open Source-like license. It is built on (and fully compatible with) Matlab Robust Control Toolbox RCT. It is dedicated to build, verify, manage Linear Fractional Transformations LFT specialized for space applications. On the one hand, it contains a library of generic LFT models relevant for space applications including typical uncertain actuators models (reaction wheels, thrusters. . .) uncertain dynamics models (flexible spacecraft, rendezvous dynamics. . .), uncertain sensors models (star trackers, gyrometer. . . ), etc. On the other hand, it implements new Matlab functions dedicated to manage the LFT models and to support robust controller synthesis and analysis.