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 Calculating acceleration and decelleration to reach a certain point in time  (Read 10181 times) 0 Members and 1 Guest are viewing this topic.
Eli Delventhal

JGO Kernel

Medals: 42
Projects: 11
Exp: 10 years

Game Engineer

 « Reply #30 - Posted 2009-04-20 22:42:39 »

A=(2*(d-V0*t))/t²

Yeah, that's as far as I got but I don't want to use time as an input, instead I want to replace that input with V(f). But naturally to find how long it takes to get from V(0) to V(f) I need to know A in the first place.

So I don't think I can use this equation.

See my work:
OTC Software
DzzD
 « Reply #31 - Posted 2009-04-20 22:43:44 »

Quote
Hm I don't think V = V0 + t*A is correct. It should be V = V0 + A + V0 + 2A + V0 + 3A ... v0 + tA which simplifies to V = t*V0 + ((t * (t+1))/2) * A .
V=V0 + t*A

this is ok, why not ? this is just derivated by t => instant velocity

EDIT :

this one may work  ....

A=-0.5*(V0-V)*(V+V0)/D

Eli Delventhal

JGO Kernel

Medals: 42
Projects: 11
Exp: 10 years

Game Engineer

 « Reply #32 - Posted 2009-04-20 23:55:01 »

Thinking about it, I guess I do need t, because you could decelerate very very slowly to get to a certain point, or very very quickly. Like the above example I have you could increase the time if you wanted to just decelerate half as quickly. So I guess once I know that all that's really missing is the final velocity I want, which I suppose I can probably figure out the place for. The equation above really calculates the value to bring the from 0 to the passed amount, no?

See my work:
OTC Software
DzzD
 « Reply #33 - Posted 2009-04-21 01:17:47 »

I think yes, if you want V=50 unit/s and D=215 unit and V0=10 unit/s :

A=-0.5*(V0-V)*(V+V0)/D

A=5.58

t is :

A=(V-V0)/t
t=(V-V0)/A
t=7.16

the solution is at t=7.16

Verification :

D at t=7.16 :

(D0 is removed because it is a constant/offset)

D=V0*t+0.5*A*t²
D=10*7.16+0.5*5.58*7.16²
D= 72+143
D=215

and V at t=7.16 :

V=V0+t*A
V=10*+7.16*5.68
V=50

good that's all right !

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