Adaptive Control of Nonminimum Phase Systems Using Sensor Blending With Application to Launch Vehicle Control

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.

1985 ◽  
Vol 107 (4) ◽  
pp. 278-283 ◽  
Author(s):  
Qiusheng Zhang ◽  
Masayoshi Tomizuka

Multivariable direct adaptive control is tested on a nonlinear thermal mixing process and is compared with state space based nonadaptive controllers. The linear quadratic optimal control approach is used to design two nonadaptive controllers: one without integral action (ordinary LQ) and the other with integral action (LQI). The operating point is changed over a wide region in the experiment. The adaptive controller is verified to perform most consistently under the tested conditions.


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.


1989 ◽  
Vol 36 (3) ◽  
pp. 361-364
Author(s):  
Jong-Hwan Kim ◽  
Yeon-Chan Hong ◽  
Sung-Jun Lee ◽  
Keh-Kun Choi

2011 ◽  
Vol 130-134 ◽  
pp. 1973-1977 ◽  
Author(s):  
Fu Yang Chen ◽  
Bin Jiang ◽  
Changan Jiang

In this paper, the control law designing of longitudinal-lateral attitude and faults self-repairing against the UAVs are analyzed. The direct adaptive controller via fuzzy feedback is designed to guarantee the UAVs stabe and having good flying performance. Then, a new direct adaptive control method is formulated by quantum control technique. Consequently, not only the stable error but the property of response and robustness is improved well. Simulation results are given to illustrate that a good dynamic performance of the flight control system with large faults can be maintained with the proposed control method.


Sign in / Sign up

Export Citation Format

Share Document