GALCIT Special Seminar
This presentation focuses on the design and validation of Control and Guidance (C&G) systems for in-space transportation vehicles. The primary objective of these vehicles is to inject the satellite into the targeted orbit within the specified dispersion band and also to bring back a launch module from space to earth, depending on the requirement. The C&G system plays a complex role in stabilizing the vehicle along the desired path to achieve the orbit within the specified accuracy against the wide range of dispersions in various parameters like propulsion, aerodynamics, ground and upper atmosphere winds etc. In addition, a wide variety of internal and external disturbances during the flight make the functions of control and guidance very complex. The navigation system on-board provides the instantaneous rotational and translational response of the vehicle during the flight. While the guidance system generates the desired vehicle attitude steering command to realize the optimum trajectory in real time, the vehicle control system, comprising of autopilot and control power plant, steers the vehicle to follow the desired attitude.
The C&G system must ensure the integrity of the vehicle during flight and direct the vehicle to the intended target under all possible environments. The design and validation of this system has to take into account high level of interaction, with a number of vehicle subsystems, such as propulsion, aerodynamics, structure, actuators, sensors, liquid sloshes and also the engines or nozzles used for control.
The demand on control force and impulse is to be carefully assessed so as to ensure they are within the capability of the control power plant. The loads should not exceed the design limits of the structures and their design should be robust. Guidance function starts at lift-off and continues till the final target conditions, during the atmospheric phase with open loop guidance and outside the atmospheric phase with closed loop guidance. The guidance law has to be robust against larger deviations of vehicle trajectory and has to provide for fault detection and isolation. The talk highlights the complexities of control and guidance design along with various processes involved in the design and validation needed for the clearance of the system for the flight.