Active Control

(1) Evaluate the system design in a simulation which incorporates as many real system hardware elements or performance parameters as practicable to determine off-nominal performance. (2) Combine the normal or 3-cr tolerances of the autopilot elements in a statistical manner with the most favorable and least favorable center-of-mass location as pro-pellant is expended. Perform the following types of statistical analysis of the system (a) Performance. Tabulate all system parameters which will...

Active Closed Loop Control

Spacecraft Attitude Control

Active attitude control provides flexibility in the spacecraft mission, allowing the vehicle to be quickly rotated to any desired orientation. The general form of an active closed-loop attitude-control system is illustrated in figure 6. The controller processes guidance commands and attitude sensor feedback signals, and generates effector commands. The controller, which may be analog, digital, or hybrid, provides signal conditioning or filtering. The effectors include the propulsive devices...

Thrust Vector Control

Spacecraft whose missions involve numerous and varied thrusting maneuvers, for example, gross orbital and trajectory changes, usually require a large thrust magnitude. This large force can be used advantageously to produce control moments on the vehicle by deflecting the thrust so that it has a moment arm with respect to the spacecraft center of mass. The technique is called thrust vector control TVC . See, for example, refs. 26 and 27. TVC is provided in two ways 1 deflecting the thrust vector...

References

NASA Space Vehicle Design Criteria Monograph Structures , NASA SP-8009, August 1968. 2. Effects of Structural Flexibility on Spacecraft Control Systems. NASA Space Vehicle Design Criteria Monograph Guidance and Control , NASA SP-8016, April 1969. 3. Spacecraft Magnetic Torques. NASA Space Vehicle Design Criteria Monograph Guidance and Control , NASA SP-8018, March 1969. 4. Spacecraft Gravitational Torques. NASA Space Vehicle Design Criteria Monograph Guidance and...

Spin Stabilization

Transverse Moment Inertia

Spin stabilization has a number of significant advantages for thrusting maneuvers, such as 1 a gyro reference package may not be needed, saving both weight and power, and 2 where the thrust is along the spin axis for a period of several spin cycles typically 10 to 200 there is an averaging of the effect of thrust misalinement. There are two major types of spin-stabilized spacecraft. One is a single rigid or quasi-rigid body spinning with respect to inertial space. The other is a multibody...