reaction wheels and CMG 2

[parvizsamadof]

Who know what is the difference between REACTION WHEELS and CONTROL MOMENT Gyros(GMC)?

 

[rb1957]

my sense is that CMGs are actively controlled whereas reaction wheels are passive (like auto-gyros)

 

[parvizsamadof]

thanks rb1957
I think like you but the mater is that in some articles I've red they have different ways to make change in direction.
Some one told me the CMG use moment vector and reaction wheels use reactions of motion?!


I want, I can, I do.

 

[IRstuff]

see:

http://en.wikipedia.org/wiki/Control_Moment_Gyro#Mechanics

http://robotics.ucsd.edu/RWAsAndCMGs.html

A CMG's speed is ostensibly constant, and torque is generated by changing the orientation of the spinning mass. A reaction wheel's torque is generated by changing the speed of rotation, which results in a reaction moment.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[rb1957]

i think that is the same as my post ... CMG you apply a control moment to them (active control), reaction wheels react to the motion of the vehicle (passive control).

 

[parvizsamadof]

I think your description is true.
and I think the difference is in their way of control.

thanks a lot for your help
be congratulate

I want, I can, I do.

 

[IRstuff]

Reaction wheels are also ostensibly "active" since their speeds are dictated by a controller that's actively trying to change the orientation of the platform.

In either case, the platform "reacts" to the torque, and in both cases, the torque requires some action by the controller, either changing the orientation of the wheel, or changing the speed.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize