Small Inline Reaction Wheel

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The S.A.S. Module is a toggleable module that acts as a sort of Autopilot to stabilize and help keep a rocket on course.

Usage

S.A.S. modules do not have to be placed anywhere in particular to function, however it will cease to function if jettisoned. They appear to function on a stability:mass ratio and the effect can be enhanced by adding additional S.A.S. modules. Often a single S.A.S. module isn't enough.


Theory

The S.A.S. modules use a P.I.D system, which stands for "Proportional, Integral, Derivative".


"Proportional" means the S.A.S. module applies a turning-force that is proportional to the displacement from the "target" orientation. In other words, the further off-line the ship, the harder the module tries to correct it.

"Derivative" means the S.A.S. module takes the rate-of-turn of the ship in to account, and tries to apply a force against the turn. So the faster the ship is pitching, yawing, or rolling, the harder the S.A.S. module tries to stop the turn. This is supposed to dampen the action of the S.A.S module, preventing overshoot, as well as dampening any fast turn or roll.

"Integral" means the S.A.S. module increases the corrective force the longer the ship is off-target. So if the ship is constantly "not-quite" on target, the S.A.S. module will ramp up the force used to correct the ship's orientation.


The S.A.S module found within the command module itself uses only PD, with no I. The reason for overshoot is that the PID system is not well-tuned yet. The "I" and "P" factors are a bit too powerful, the "D" factor (which dampens movements) is a bit too weak.

Description

SAS: Stability Augmentation System, Spin Auto-Stabilizer, Sickness Avoidance Solution. Whatever you choose to call it, it makes the ship stop spinning around.

O.M.B. Demolition Enterprises

Changes

→ See also: Version History

v0.8.5

  • Exposed Kd, Ki and Kp parameters for tuning the SAS module

v0.8

  • SAS toggle with 'T' key

v0.7.3

  • Initial Release