Difference between revisions of "SAS"

Revision as of 17:57, 17 April 2013

SAS is a flight system that will help control your ship by countering rotation. Advanced SAS (ASAS) adds to this by also controlling heading. SAS is distinct from S.A.S, as the latter is a ship part (which adds command authority to the flight system by exerting torque).

Effect

SAS directly runs your ship controls as if it were pressing the "qweasd" keys. You can see it functioning by looking at the bottom left-hand corner and watching the pitch, yaw, and roll twitch around. You can control the ship at the same time, but the inputs are additive, so the SAS may fight you. This can be useful when trying to make slow movements or fine adjustments.

Since ASAS also controls heading, it can be extremely useful for lander missions. Turn on SAS while facing straight up (relative to the surface) and then use the arrow keys to fight the ASAS and kill lateral motion. The ASAS will keep returning your vessel to upright so you can focus on steering without worrying about falling over.

Control

You can turn the system on and off with the T key, and temporarily invert the state by holding the F key (For example, if SAS is on, holding F will turn it off, and releasing F will turn it back on). The current state of the SAS system is shown by a light on your Navball. The SAS and ASAS are controlled together, as ASAS adds heading control to the standard SAS rotation dampening.

All command pods offer a small amount of SAS torque, and you can add to this by adding more SAS units to the craft. ASAS however is simply either there or not, you can not add multiple units to increase its effect.

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.
• 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.
• 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.

The SAS functionality found within command modules use 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.

Advanced S.A.S. does not produce torque itself, it uses controllable components instead.

SAS/ASAS Parts

The game currently offers four SAS/ASAS units; a small radius SAS, a small radius ASAS, a large radius ASAS and an 'avionics package'. You also get some SAS functionality from command modules.

Dedicated Units

Image	Part	Radial size	Cost ()	Mass (t)	Max. Temp. (K)	Tolerance (m/s)	Tolerance (g)	Torque (kN·m)	Electricity (⚡/s)
	Small Inline Reaction Wheel	Tiny	600	0.05	2 000	9	50	5	0.25 (15 ⚡/min)
	Advanced Inline Stabilizer	Small	1 200	0.1	2 000	9	50	15	0.45 (27 ⚡/min)
	Advanced Reaction Wheel Module, Large	Large	2 100	0.2	2 000	9	50	30	0.6 (36 ⚡/min)

Command Pods

Template:Stats Table Commands Pods