Greetings,
I'm reading "ESL 04-10: Simulation of Vehicle Longitudinal Dynamics" in
an attempt to write a car simulations engine. However I came across
several dilemmas and was hoping to find answers here
- In page 3 an equation (04/01/C) of the form: V = (-Fxt +
g*sin(theta) - Fd(V)) / m
Was supposed to give the velocity of the car as the net force divided
by mass. However, IIRC such a formula would give the acceleration not
the velocity (A similar equation was given in page 6 for the angular
velocity)
- Another equation (04/01/D):
Fz = mg {(C/L)cos(theta) + (H/L)sin(theta)} - mV (H/L)
Is supposed to give the normal force on the front wheels. Which is a
variable controlling the total force (Fxt) in the first equation
(04/01/C). Now suppose that theta is 0 which means that the fist term
would evaluate to zero, and suppose that the car is starting with zero
velocity which means that the second term is also zero. And Fz is zero
as a whole, hence Fxt is also zero (No force is acting on the vehicle
body). Since Fxt is zero this would mean that V is also zero (from the
first equation). And we are faced with a paradox: The car won't move
until a force is applied to it, but no force will be applied until the
car moves. I suppose that in real life clutching/declutching the engine
will solve this problem, however how can I solve such a problem in a
simulation?
PS: Article link: www.le.ac.uk/eg/embedded/pdf/ESL04-01.pdf
Thank you for your time
Abdo Haji-Ali
Programmer
In|Framez
You just made my head 'Splode.
-Larry
"Abdo Haji-Ali" <[email hidden]> wrote in message
news:[email hidden]...
Quoted text (34 lines)
> Greetings, > > I'm reading "ESL 04-10: Simulation of Vehicle Longitudinal Dynamics" in > an attempt to write a car simulations engine. However I came across > several dilemmas and was hoping to find answers here > > - In page 3 an equation (04/01/C) of the form: V = (-Fxt + > g*sin(theta) - Fd(V)) / m > Was supposed to give the velocity of the car as the net force divided > by mass. However, IIRC such a formula would give the acceleration not > the velocity (A similar equation was given in page 6 for the angular > velocity) > - Another equation (04/01/D): > Fz = mg {(C/L)cos(theta) + (H/L)sin(theta)} - mV (H/L) > Is supposed to give the normal force on the front wheels. Which is a > variable controlling the total force (Fxt) in the first equation > (04/01/C). Now suppose that theta is 0 which means that the fist term > would evaluate to zero, and suppose that the car is starting with zero > velocity which means that the second term is also zero. And Fz is zero > as a whole, hence Fxt is also zero (No force is acting on the vehicle > body). Since Fxt is zero this would mean that V is also zero (from the > first equation). And we are faced with a paradox: The car won't move > until a force is applied to it, but no force will be applied until the > car moves. I suppose that in real life clutching/declutching the engine > will solve this problem, however how can I solve such a problem in a > simulation? > > PS: Article link: www.le.ac.uk/eg/embedded/pdf/ESL04-01.pdf > > Thank you for your time > Abdo Haji-Ali > Programmer > In|Framez >
Abdo Haji-Ali wrote:
> Greetings,
>
> I'm reading "ESL 04-10: Simulation of Vehicle Longitudinal Dynamics"
Don't spoil the ending for the rest of us.... ;)
"Abdo Haji-Ali" wrote:
> I'm reading "ESL 04-10: Simulation of Vehicle Longitudinal Dynamics" in
> an attempt to write a car simulations engine. However I came across
> several dilemmas and was hoping to find answers here
http://groups.google.com/groups?as_q=car+physics&as_ugroup=rec.autos.simulators
Happy reading!
j
