Performance Comparison of Sliding Mode Techniques for LISA Mission

This paper focuses on the design of the controllers for the release phase of the Test Masses (TMs) of the LISA (Laser Interferometer Space Antenna) mission. Space gravitational observatories such as LISA will be complementary in future years to existing terrestrial laboratories for detecting low-frequency gravitational signals that cannot be measured from Earth. TMs are used as sensors in science phase for environmental measurements; their control system must therefore be able to stabilize TMs with a limited control authority in spite of uncertainties and noises. In this paper, two sliding mode techniques are analysed and compared in terms of performance metrics, considering two operative modes and strict requirements in terms of accuracy and steady-state error. Extensive simulations are performed, taking into account a wide range of cases by varying noises and disturbances affecting the systems. In addition, the critical initial conditions of LISA Pathfinder (the previous mission) and their effects are analysed by using a nonlinear spacecraft dynamics.