A fixed planar chain of three unit masses, anchored at the origin and driven at the other end along (1.25 cos T, 3.5).

Collaboration diagram for Fixed planar chain:

Author: Jørgen Haavind Jensen

Date: 01.04.2011 JHJ: Initial version.

Review issues:: 0028 — The whole RbCable family (RMCable, RBCable, Cable6Dof, CableRM, Ring) has zero automated test coverage

The chain has four links of unit length: origin to mass 0, mass 0 to mass 1, mass 1 to mass 2, and mass 2 to the moving end point. The geometry (link lengths, unit masses), the element count (three masses) and the end-point trajectory are hard-coded in OdeFcn; no parameter or port changes them. The link-length constraints are enforced with Baumgarte stabilisation; no external force acts on the masses.

Example configuration excerpt

<Lib
  LibName            = "marine_elements"
  SimObject          = "RbCable/RMCable"
  Name               = "C"
  Alpha              = "5"
  Beta               = "5"
/>

Input Ports

This simObject does not contain any input ports.

Output Ports

Name	Width	Description
totalLength	1	Summed length of the first three links minus 3 (their length error). The fourth link is not included.
kineticEnergy	1	Kinetic energy of the three unit masses

Configuration parameters

Name	Width	Description
Alpha	1	Baumgarte stabilisation gain on the constraint velocity error (enters as 2 Alpha).
Beta	1	Baumgarte stabilisation gain on the constraint position error (enters as Beta squared).

Initial conditions

Name	Width	Description
pos0	2	Position of mass 0 in the plane
pos1	2	Position of mass 1 in the plane
pos2	2	Position of mass 2 in the plane
vel0	2	Velocity of mass 0
vel1	2	Velocity of mass 1
vel2	2	Velocity of mass 2

Full example file

tests/in/RMCable/RMCable_in.xml starts the chain on all four constraints at T = 0.