[ODE] Vehicle Speed (Generic Units to Real World Units)

[Jeff Weber]

Our app does require that a 20 mile trip at 60 mph takes a real-world amount 
of time.

I think the piece i'm missing is the conversion factor between the arbitrary 
time unit and seconds.

Since I already arbitrarily said 8 "ode" units = 1 meter I should be able to 
measure/calculate the conversion between arbitrary units and seconds.

Let me know if this makes sense or if there is an easier way.

I set my wheel joint's desired velocity to 1 and let the vehicle reach it's 
max speed.

dBodyGetLinearVel returns a value of say 3.79 distance-units/time-unit.

Or, using my conversion factor this equals .473 meters/time-unit

Now, I mark off a distance of 100 meters in my 3d world and find that the 
vehicle (at it's max speed) takes 26 seconds to go 100 meters. This means 
that it was going 3.84 (100/26) meters/second.

I can then use this to determine that 1 arbitrary time unit = (.473/3.84) 
seconds.

Does this make sense or am i making it to complicated??


----Original Message Follows----
From: "Martin C. Martin" <martin@metahuman.org>
To: Jeff Weber <jeffreyweber@hotmail.com>
CC: ode@q12.org
Subject: Re: [ODE] Vehicle Speed (Generic Units to Real World Units)
Date: Wed, 30 Jul 2003 09:01:10 -0400

When you call dWorldStep(), do you call it with the number of wall clock
seconds that have passed, or otherwise try to keep simulation time the
same as wall clock time?

Remember, the units of time are arbitrary as well.

- Martin

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