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Author Topic: Detumble (1DOF)  (Read 1567 times)

Cosmoneer

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Detumble (1DOF)
« on: November 11, 2016, 12:16:23 PM »
What is the background?
This challenge is based on the idea that if a spacecraft were to experience loss of control, that it would be able to regain control, despite CMG "saturation", which is where the usable torque of the CMG is used up and no more torque can be harnessed from the CMG.  The challenge is how quickly can the Cosmoneer regain control and locate the base station and acquire signal lock (a specified amount of time communicating via Serial IrDa).

How could this challenge be executed?
A concept we've termed "swimming" might be applied to overcome saturation.  Saturation exists in a reaction wheel based system because the momentum built up in the wheel cannot be dumped.  In a CMG environment, it may be possible to "dump" momentum by driving the a CMG (or a CMG cluster) to a "singularity" point.  Singularities are points at which a CMG's output torque reaches zero, despite the CMG gimbal actively precessing the gyro.

In swimming, the gyro motor's speed is reduced to zero once a singularity point is reached and the gimbals drive the gyros back to a point of maximum torque output to counteract the spin in the desired axis.  Once this gimbal angle is acquired, the Gyro motors are started up and precessed by the gimbal.

What might affect this challenge?
This challenge will be affected by the CMG's ability (or inability) to regain control of the attitude.  If momentum dumping is not possible, then the Cosmoneer will never be able to regain control.  Servo/Gyro accuracy will somewhat affect this challenge.
« Last Edit: November 11, 2016, 01:08:53 PM by Cosmoneer »