On Thu, 2003-10-23 at 14:55, Pierce Nichols wrote: > On Thu, 2003-10-23 at 00:15, David Masten wrote: > > > I had figured that to yaw left decrease left engine thrust and increase > > right engine thrust simultaneously. Since opposite motors generate > > torque in the same direction this should mean no (little) torque change. > > Neither the strategy you propose nor John's strategy eliminate > cross-axis coupling. Both strategies still produces coupling to the roll > axis when maneuvering in both pitch and yaw at the same time.
I'm having problems visualizing the coupling problem.
If we have a POGO type vehicle and roll is the rotation around the axis
perpendicular to the ground when not flying. Engines are:
#1 at a,0,0 cant gives +roll
#2 at -a,0,0 cant gives +roll
#3 at 0,a,0 cant gives -roll
#4 at 0,-a,0 cant gives -roll
We assume that the vehicle is hovering with no wind. We wish to give the
vehicle a vector of force - (1,1,0) thus moving obliquely. We do not
care about maintaining altitude (for now), but we wish to not induce
roll.
thrust roll change for axis
#1 -1 -1
#2 +1 +1 0
#3 -1 -1
#4 +1 +1 0
So we have no change in roll, while changing pitch and yaw.
What about the case of force change (2,1,0)?
thrust roll change for axis
#1 -2 -2
#2 +2 +2 0
#3 -1 -1
#4 +1 +1 0
Still, rolls cancel. Okay, lets look at maintaining altitude (2,1,0):
#1 -1.9 -1.9
#2 +2.1 +2.1 +0.2
#3 -0.9 -0.9
#4 +1.1 +1.1 -0.2
Looks like they still cancel.
What am I missing?
Dave
--
David Masten <[EMAIL PROTECTED]>
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