Amaral, J. and de Oliveira e Souza, M., "Application of Methods to Smooth the Transition Between Control Submodes in the Nominal Mode of the Multimission Platform," SAE Technical Paper 2012-36-0378, 2012, doi:10.4271/2012-36-0378.
The Multimission Platform (MMP) is a generic service module currently in Project at INPE. In the 2001 version, its control system can be switched between nine main Operation Modes and other submodes, according to information from satellite sensors and ground commands. The Nominal Mode stabilizes the MMP in three axes and takes it to a nominal attitude, using three reaction wheels. Each wheel has coarse and fine acquisition submodes. The use of multiple modes of control for specific situations frequently is simpler than projecting a single controller for all cases. However, besides being harder to warrant its general stability, the mere switching between these submodes generates bumps, which can reduce the performance and even damage the actuator or plant. In this work, we present an application of diverse methods to smooth the transition between control submodes of the Nominal Mode of the MMP. We will use techniques including, but not limited to, output tracking, anti-windup and crossfading to compare and identify the combinations which produce the more satisfactory results. The tests are based in simulations with the software MatrixX/Systembuild, of National Instruments, which helps developers with tools to model, analyze and test control systems. The tests focus on the worst cases the satellite may face. Being able to withstand these worst cases, the control system is considered apt to simpler situations. The tests show that many of the adopted strategies could smooth the transition and improve the performance of the system, and it was possible to identify advantages and disadvantages of each one.