Lecture - 7 ( degrees of freedom (part -3) )


  • If degrees of freedom 'F' is zero for any linkage combination then it will become a frame or structure. In this case no relative motion is there between links.

For example-

L=3 ; J=3 ; H=0 ; N=0
F = 3(L-1) - 2(J) - H - N = 3(3-1) - 2(3) - 0 - 0 = 0
F = 0 
  • If degrees of freedom 'F' is less than zero for any linkage combination then it will become a superstructures. In this case also no relative motion is there between links. Buildings and bridges are called superstructures.

For example-

L=4 ; J=5 ; H=0 ; N=0
 F = -1

 [ In structures and superstructures force and torque will travel from link to link but relative motion will not occur]

  • If degrees of freedom'F' is one for any linkage combination then it will become a Kinematic chain or constrained chain. In this case for one input we get one desired output.

For example-

L=4 ; J=4 ; H=0 ; N=0
F = 1
  • If degrees of freedom'F' is more than one for any linkage combination then it will become an unconstrained chain. In this case for one input we get multiple outputs.
For example -

L=5 ; J=5 ; H=0 ; N=0
 F = 2

 For more continue to lecture-8

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