Dear Colleagues,

I have a requirement to simulate the sequential deployment of multiple structures that are folded at t=0. The links are connected with revolute joints that are "spring loaded" with a spring + damper component and are "held" in their folded configuration by clutch components. The clutches are "released" sequentially by step commands.

During tests I have noticed that the build time reported by the Simulation Center increases exponentially with the number of clutches, as tabulated below

Clutch cnt   Time (s)
0              25
1              34
2              63
3             108
4             247
5            1085

The 18 minutes of build time for five clutches is quite sobering and I cannot afford to wait that long during testing. Moreover, I have to add seven more clutches for other structures and I am worried that the model will become useless because of the long build time.

The only message from the Simulation Center that might have some bearing on the problem is

Warning: [LIN_SYS] LU decomposition of linear system failed (U[2, 2] is exactly zero). Using complete orthogonal decomposition from now on. [170»] [@0.0 s]

I have read quite a bit of SystemModeler documentation on clutches and simulation set up but I haven't been able to figure out if I am doing something wrong or if SystemModeler has a bug. I would appreciate any suggestions or help.

After I post this message I am going to try other methods of holding the joints in their stowed positions with something else but a clutch.

Thank you.

BU