Aerospace Control Systems

Spacecraft GNC Systems Engineering


Specialized Software Tools for Pointing Control and Calibration

ACS has significant experience in algorithm and software development to deliver reliable and efficient software implementations of control systems and simulations. ACS has experience in developing engineering and simulation software using C, Matlab, and Simulink. Control system design and analysis are performed by using the following Matlab toolboxes: Control System, Robust Control, and Signal Processing, and others. ACS can also perform pointing analyses and simulations using STK.

In addition to standard commercial software tools, specific software tools have been developed to aid in performing analysis and control system design. Some of the software tools used to perform attitude determination and control system design and analysis are described in the articles below. Check this page periodically for information on other software tools that have been developed and that are currently being developed.

Contact ACS if you feel that these software tools can benefit your spacecraft programs.

RADICAL RIMU Attitude Determination/Calibration Filter PDF Print E-mail

Precise attitude determination requires that attitude sensor and gyro parameters be calibrated accurately. It is often the case that attitude sensor and gyro calibration are not carefully considered in the design and operation of a system, or the calibration algorithm and its software implementation are limited in their capability or performance. A well designed calibration algorithm and software tools are necessary to conduct early trade studies and to predict performance, to quickly design and implement a system, and to achieve optimum system performance during operation.

Pointing Error Analysis Tool PDF Print E-mail

The Pointing Error Analysis Tool is a set of Matlab functions that are used to evaluate the Standard Pointing Error Metrics from time-domain and frequency-domain data. The pointing error metrics are called the accuracy metric, displacement metric, jitter metric, stability metric, and the windowed stability metric. These metrics are based on unambiguous mathematical models involving the point spread function of optical instruments, and therefore relate the pointing error directly to instrument performance. The mean-square pointing error is expressed by exactly equivalent equations in the time domain and in the frequency domain.

Structural Model Reduction Tool PDF Print E-mail

The Structural Model Reduction Tool is used to reduce the order of Nastran structural models while retaining essential characteristics of the full model. The full Nastran model can have hundreds or thousands of modes and nodes, whereas a practical model for control system design and analysis has a much smaller number structural modes, inputs, and outputs.

Control-Structure Interaction (CSI) Analysis Tool PDF Print E-mail

The CSI Analysis Tool is used to evaluate control-structure interaction and control system stability, and to compute the pointing error response of spacecraft and optical payloads to disturbances and sensor noise. This Matlab tool models the rigid-body and flexible structure, attitude sensors and gyros, reaction wheels, the steady-state attitude determination (Kalman) filter, a three-axis PID controller, structural mode filters, payload dynamics (including line-of-sight stabilizers), and time delays. The component transfer functions are interconnected to form system matrices, from which the open-loop and closed-loop frequency response to inputs and disturbances, and the covariance response to noise can be evaluated.

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