LSS Vibratinal/Rotational Control Taking Into Account the Thermal Effects on the PZT Sensor Output Signals
- Paper number
IAC-08.C2.3.7
- Author
Dr. Ijar M. Da Fonseca, Instituto Nacional de Pesquisas Espaciais (INPE) - MCT, Brazil
- Coauthor
Prof. Peter M. Bainum, Howard University, United States
- Year
2008
- Abstract
This paper presents the active control of a LSS vibrational/rotational motion in a low earth orbit (LEO), subjected to the gravity-gradient and the aerodynamics effects. The LSS dynamics is characterized by rigid and flexible motion interaction under the active control and zero-g environment allowing for the control structure interaction (CSI) analysis in addition the attitude and vibrational control performance study. The main features considered for the space environment are the gravity-gradient torque and the aerodynamics effect. Both of those aspects are consistent with the low Earth orbit and the large flight area of the solar arrays assumed for the LSS model. The LSS attitude control system (ACS) includes reaction wheels and thrusters as actuators and zirconate-titanate piezoelectric (PZT) ceramic sensors as part of the control subsystem to suppress the solar array vibrations. The paper includes the thermal effects on the outputs of the PZT and the consequent impact on the control performance. The temperature gradient strongly affects the spacecraft. The temperature falls down when the spacecraft enters the Earth’s shadow and then increases very much when the space vehicle comes to the Sunlight again. The piezoelectric element is placed on the solar array surface and subjected to that temperature gradient. The Lagrangian formulation for quasi-coordinates and for generalized coordinates combined with the assumed mode discretization technique is used to obtain the equations of motion. The mathematical models of the piezoelectric sensors and the actuators (reaction wheels and thrusters) are included in control loop simulations to give the study some sense for realistic applications. The computer simulations have been implemented by using the MatLab®/Simulink software package. The results enhance the thermal effects on the PZT output signals that affect the ACS performance.
- Abstract document
- Manuscript document
IAC-08.C2.3.7.pdf (🔒 authorized access only).
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