Rigid body separation dynamics for space launch vehicles

2006 ◽  
Vol 110 (1107) ◽  
pp. 289-302 ◽  
Author(s):  
B. N. Rao ◽  
D. Jeyakumar ◽  
K. K. Biswas ◽  
S. Swaminathan ◽  
E. Janardhana

Abstract This paper presents a systematic formulation for the simulation of rigid body dynamics, including the short period dynamics, inherent to stage separation and jettisoning parts of a satellite launcher. This also gives a review of various types of separations involved in a launch vehicle. The problem is sufficiently large and complex; the methodology involves iterations at successively lower levels of abstraction. The best choice to tackle such problems is to use state-of-the-art programming technique known as object oriented programming. The necessary classes have been identified to represent various entities in the launch vehicle separation process (e.g., gravity, aerodynamics, propulsion and separation mechanisms etc.). Simple linkages are modelled with suitable objects. This approach helps the designer to simulate a launch vehicle separation dynamics and also to analyse separation system performance. To examine the influence of the design variables on the separating bodies, statistical analyses have been performed on the upper stage separation process and pull out of ongoing stage nozzle from the spent stage of a multistage rocket carrier using retro rockets.

Author(s):  
Mark J. Balas

The goal of this paper is to investigate the use of a very simple direct adaptive controller in the guidance of a large, flexible launch vehicle. The adaptive controller, requiring no on-line information about the plant other than sensor outputs, would be a more robust candidate controller in the presence of unmodeled plant dynamics than a model-based fixed gain linear controller. NASA’s seven-state FRACTAL academic model for ARES I-X was employed as an example launch vehicle on which to develop the controller. To better understand the difficult dynamic issues, we started with a simplified model that incorporated the inherent instability of the plant and the nonminimum phase nature of the dynamics: an inverted pendulum with an attachable slosh tank. We formulated controllers for this simplified plant with slosh dynamics using control algorithms developed only on a reduced–order model consisting of the rigid body dynamics without slosh. The controllers must be designed to reject three different persistent input disturbances: persistent pulse, step, and sine. We assumed that only position feedback was available, and that rates would have to be estimated. For comparison, a fixed gain linear controller was developed using the well-known Linear Quadratic Gaussian methodology employing state estimation to obtain rate estimates. For a stable adaptive controller, we used direct adaptive control theory developed by Balas, et al. For this theory we need CB > 0 and a minimum-phase open-loop transfer function. We employed a new transmission zero selection method to develop a blended output shaping matrix which would satisfy these conditions robustly. We used approximate differentiation filters to obtain rates for the adaptive controller. Again for comparison, we redesigned the LQG controller to use the same blended output matrix and filters. Following the work on the pendulum, the same method was applied to develop an adaptive controller for the FRACTAL launch vehicle model. An adaptive controller stabilizes a rigid body version of FRACTAL over a very long timeline while exceeding all reasonable state and output limits.


Author(s):  
Mate Antali ◽  
Gabor Stepan

AbstractIn this paper, the general kinematics and dynamics of a rigid body is analysed, which is in contact with two rigid surfaces in the presence of dry friction. Due to the rolling or slipping state at each contact point, four kinematic scenarios occur. In the two-point rolling case, the contact forces are undetermined; consequently, the condition of the static friction forces cannot be checked from the Coulomb model to decide whether two-point rolling is possible. However, this issue can be resolved within the scope of rigid body dynamics by analysing the nonsmooth vector field of the system at the possible transitions between slipping and rolling. Based on the concept of limit directions of codimension-2 discontinuities, a method is presented to determine the conditions when the two-point rolling is realizable without slipping.


2015 ◽  
Vol 69 ◽  
pp. 40-44
Author(s):  
H.M. Yehia ◽  
E. Saleh ◽  
S.F. Megahid

2014 ◽  
Vol 10 (2) ◽  
pp. e1003456 ◽  
Author(s):  
Pascal Carrivain ◽  
Maria Barbi ◽  
Jean-Marc Victor

Author(s):  
Kikuo Fujita ◽  
Shinsuke Akagi

Abstract A Framework of computational design method and model is proposed for layout and geometry design of complicated mechanical systems, which is named “configuration network and its viewing control”. In the method, a design object is represented with a set of declarative relationships among various elements of a system, that is, configurations, which is gradually extended from schematic structure to exact layout and geometry through design process. Since a whole of such configurations forms a too complicated network to compute all together, how to view subparts is controlled based on levels of granularity and width of scope range. Such a configuration network is made to grow and refined through embodying geometry and layout corresponding to a focused subpart with a numerical optimization procedure. The framework has also an ability to flexibly integrate with engineering analysis. Moreover, a design system is implemented with an object-oriented programming technique, and it is applied to a design problem of air conditioner units in order to show the validity and effectiveness of the framework.


1986 ◽  
Vol 54 (7) ◽  
pp. 585-586
Author(s):  
Stephen F. Felszeghy

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