Re: your post
- To: mathgroup at smc.vnet.net
- Subject: [mg15523] Re: your post
- From: Paula Chammas <chammas at dbag.bln.daimlerbenz.com>
- Date: Mon, 18 Jan 1999 23:47:23 -0500
- References: <199901180804.DAA19895@smc.vnet.net.>
- Sender: owner-wri-mathgroup at wolfram.com
Dear All,
At the beginning of December I posted a question regarding NDSolve.
Thanks for all the responses. I managed to solve the problem using the
following:
NDSolve[{
w'[t] == -2 w[t] + Tin[t] - Sign[w[t] - v[t]] 2/3 Fn[t],
v'[t] == (-v[t] + Sign[w[t] - v[t]] 2/3 Fn[t] )/5, w[0]==0, v[0]==0},
{w,v}, {t, 0, 10}, MaxSteps->40000, AccuracyGoal->2}
given
Tin[t] := -2 t + 12 /; (5 <= t && t <= 6)
Tin[t] := 2 /; (0 <= t && t
<=5)
Tin[t] := 0 /; (6 <= t && t <= 10)
Fn[t] := 0.785 t /; (0 <= t && t <=
2)
Fn[t] := 1.57 /; (2 <= t && t <=5)
Fn[t] := -0.785 t + 5.495 /; (5 <= t && t <= 7)
Fn[t] := 0 /; (7 <= t && t <= 10)
Now the system becomes more involved.
The new system look like the following: 2 clutches C1 and C2 in parallel
w T1,C1 v
Tin -------||----- Tout
----m T2,C2 n------
-------||-----
Tin is input torque, it is given (see below) and Tin = T1 + T2
w, m are input speeds
v,n are ouput speeds
So basically we have 2 sets of equations one for C1 and one for C2:
w'[t] == -2 w[t] + T1[t] - Sign[w[t] - v[t]] 2/3 Fn[t],
v'[t] == ( -v[t]+ Sign[w[t] - v[t]] 2/3 Fn[t] )/5,
m'[t] == -2 m[t] + T2[t] - Sign[m[t] - n[t]] Fn[t],
n'[t] == ( -n[t] + Sign[m[t] - n[t]] Fn[t] )/5
with the following constraints:
Tin[t] = T1[t] + T2[t]
w[t] = m[t]
v[t] = n[t]
v[0] = w[0] = m[0] = n[0] = 0
{t, 0, 10}
Fn[t], and Tin[t] are given above.
T1 and T2 should be determined by the system
When I try to solve the system it does not like the equation
Tin[t] = T1[t] + T2[t]
I get :
Input is not an ordinary differential equation of T1[t]
and in some cases
NDSolve:: ndsv: Cannot find a starting point of t
What is the best way of formulating the problem using mathematica?
Any ideas?
Thanks in advance and a happy New year to all.
Paula
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Paula Chammas
DaimlerChrysler
Research and Technology !!NEW Alt-Moabit 96A
Tel: +49 30 39982 376 10559 Berlin fax: +49 30 39982 107
paula.chammas at daimlerchrysler.com
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Experience is a hard teacher because she gives the test first, the lesson afterward.