[ODE] On torque ..

[Wenzel Jakob]

Hello,

thanks for your reply. I had a look at your links and altough I couldn't
make much of the russian article, I am now sure I need a PID controller
to smoothen out the movement. However, after hours of googling around, I
am still stuck with thiode at q12.orgs (probably very easy) math problem:

I have two direction vectors. The first one is the current forward
vector, the second one is where I want the forward vector to be after
the torque has been applied and the object has rotated for some time.

So what I did is, I converted the two direction vectors into a
spherical coordinate system (phi, theta), took the difference and
used this as torque. This led to very strange results, I tried
several different algorithms to convert between the coordinate systems
(I suspect this is the cause of error).

Any ideas?

Thanks in advance,
Wenzel Jakob

> Hello Wenzel,
>
>> This function should return the torque which needs to be applied to
>> the body in order to rotate the coordinate system onto the new
>> forward vector in the given amount of time.
>
>
> there is an approach to get torque which performs desired rotation.
> this one I seen in russian here
>  http://www.gamedev.ru/articles/read.shtml?id=30127&page=1 but I do
> not
> think this will suite you as this one does not take time
> into account.
>
> another approach is to solve optimal problem of rotation of the body
> which is usually used in space applications 'optimizing' the applied
> torque. the 'optimal ' solution as a rule will consist of three stepts
> - the first  acceleration phase then free rotation phase then
> deaccelearation phase. But as you need not achive min  'applied over
> time' torque you might to make the following.
>
> to develop a controller which will output desired torque observing
> rotation of the given  body I suggest to get idea - to
> read an article here http://www.ntu.edu.sg/centre/sec/P0609.pdf
>
> and develop a   controller ( maybe be even proportional controller
> will suite but maybe you will prefer PID  or maybe fuzzy :)
> controller) which for example will keep constant angular vel.
>
> so from desired angular rotation and time you get desired angular
> rotation speed - then you pass it to controller which outputs
> controlling torque...
>
> I might tell  that from my experince to keep a desired angular
> rotation with a controller which outputs desired torque is not a prob.
>
> Regards
> Sergey Kurdakov