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{{Dimensions
{{Dimensions
|nd        = 1
|nd        = 1
|nx        = 2
|nx        = 3
|nw       = 1
|nu       = 1
|nre      = 2
|nc        = 4
|nre      = 5
}}<!-- Do not insert line break here or Dimensions Box moves up in the layout...
}}<!-- Do not insert line break here or Dimensions Box moves up in the layout...


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  \mbox{s.t.} & \dot{x}_1 & = &  u, \\
  \mbox{s.t.} & \dot{x}_1 & = &  u, \\
  & \dot{x}_2 & = & x_1 (1+u^2)^{1/2},  \\
  & \dot{x}_2 & = & x_1 (1+u^2)^{1/2},  \\
  & \dot{x}_3 & = & (1+u^2)^{1/2), \\
  & \dot{x}_3 & = & (1+u^2)^{1/2}, \\
& x(t_0) &=& (a,0,0)^T, \\
& x_1(t_f) &=& b, \\
& x_3(t_f) &=& Lp, \\
& x_i(t) &\in& [0,10], \quad i=1,2,3, \\
& u(t) &\in&  [-10,20].
\end{array}  
\end{array}  
</math>
</math>
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In this model the parameters used are
In this model the parameters used are
<math>
\begin{array}{rcl}
\begin{array}{rcl}
[t_0, t_f] &=& [0, 1],\\
[t_0, t_f] &=& [0, 1],\\
(a,b) &=& (0.4, 0.2),\\
(a,b) &=& (1,3),\\
Lp &=& 4.
Lp &=& 4.
\end{array}
\end{array}
</math>


== Source Code ==
== Source Code ==
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* [[:Category:AMPL/TACO | AMPL/TACO code]] at [[Hanging chain problem (TACO)]]
* [[:Category:AMPL/TACO | AMPL/TACO code]] at [[Hanging chain problem (TACO)]]
 
* [[:Category:Gekko | GEKKO Python code]] at [[Hanging chain problem (GEKKO)]]


<!--List of all categories this page is part of. List characterization of solution behavior, model properties, ore presence of implementation details (e.g., AMPL for AMPL model) here -->
<!--List of all categories this page is part of. List characterization of solution behavior, model properties, ore presence of implementation details (e.g., AMPL for AMPL model) here -->
[[Category:MIOCP]]
[[Category:MIOCP]]
[[Category:ODE model]]
[[Category:ODE model]]
[[Category: Tracking objective]]
[[Category:Minimum energy]]

Latest revision as of 16:04, 22 February 2026

Hanging chain problem
State dimension: 1
Differential states: 3
Continuous control functions: 1
Path constraints: 4
Interior point equalities: 5

The Hanging chain problem is concerned with finding a chain (of uniform density) of length L suspendend between two points a,b with minimal potential energy. (Problem taken from the COPS library)


Mathematical formulation

The problem is given by

minx,ux2(tf)s.t.x˙1=u,x˙2=x1(1+u2)1/2,x˙3=(1+u2)1/2,x(t0)=(a,0,0)T,x1(tf)=b,x3(tf)=Lp,xi(t)[0,10],i=1,2,3,u(t)[10,20].

Parameters

In this model the parameters used are

[t0,tf]=[0,1],(a,b)=(1,3),Lp=4.

Source Code

Model descriptions are available in