I think I'd go a different approach.  Linear algebra is my forte, so I tend
to use it a lot.

You sample your positional data, and turn that into a velocity curve.  You
can fit this, for most cases, to a linear or quadratic formula.  All the
other parts of the crane, which may rotate or telescope, etc. can be
calculated by summing vectors.  In order to predict where the parts will
be, you check the values of the first and second order derivatives (I know,
calculus! ugh!, but this one's easy, really).  If f' is acceleration, and
f" is the rate of change of acceleration.  You try to solve the system of
equations, if the formulas equate, then you collide.  You look at f' to
figure out what the positional data will be like at some point in the
future, and use f" to figure out whether to over or under-estimate your
coordiate values.

Sounds complex, but I used this system in a model train world once.  I had
6 trains wizzing around the tracks, and the switching, braking, and power
were all controlled by a TRS-80 CoCo2.  Not a whole lot of CPU there (Z80,
of course), but it got the job done admirably.

You may loose some elegance with the lack of an FPU, but the most you have
to do is the occasional square root.  All the rest is integer math.

Ken

At 03:53 PM 8/29/98 -0700, you wrote:
>A numerical analysis problem!  I love it!  <G>