Passive Stability Design for a Sailcraft
- Paper number
IAC-07-C4.6.04
- Author
Dr. Gong Shengping, Tsinghua University, China
- Coauthor
Dr. Junfeng Li, China
- Coauthor
Dr. Hexi Baoyin, Tsinghua University, China
- Coauthor
Mr. Hui Yu, Tsinghua University, China
- Year
2007
- Abstract
This paper discusses the criterions for the passive stability design of a sailcraft. Three criterions should be satisfied if the sailcraft orbit is expected to be stable. Firstly, the attitude required to generate the desired orbit should be an equilibrium position for the attitude. Secondly, the summation of all external torques exerted on the mass center of the sailcraft should be zero when the sailcraft is in equilibrium position. Thirdly, a restoring force or restoring torque should be generated when the orbit or attitude deviates from the equilibrium position. According to the criterions, the sailcraft can be designed when the desired orbit is given. Based on the parameters of the designed sailcraft, the attitude dynamics of the sailcraft can be obtained and it can be combined with the orbital dynamics to obtain the coupled dynamics. According to the design criterions, the attitude equilibrium position is the attitude required to generate the required orbit. Therefore, the equilibrium point of the coupled equations is generated. The coupled equations are linearized in the vicinity of the equilibrium point. Then, the stability of the attitude and orbit can be discussed by investigating the coefficient matrix of the linear coupled equations. Based on the linear coupled equations, the design parameters can be optimized to guarantee that the system is stable and some performance is relative high. A four-triangle-form sail is adopted in this paper. The sailcraft on the displaced orbit is used to validate the method proposed above. Numerical examples are given and the results show that both the attitude and orbit are stable when the sailcraft is evolving on the displaced orbit if all the sailcraft is designed based on the criterions.
- Abstract document