Kinematic Inversion

What is the meaning of inversion of 4 bar mechanism and how does it affect design of mechanisms ?

Kinematic inversion is a key concept when it comes to designing mechanisms as part of a product or system .

  • Whenever we construct a mechanism , a link must be chosen as fixed.
  • That fixed link is called frame.
  • For a mechanism with 4 links, we can select all 4 links as fixed frame in 4 cases and that would give us 4 variations of the same mechanism
  • This is called as inversion of mechanisms
  • A mechanism with n links will have n no. of inversions

Kinematic inversion is a technique used in mechanism design and analysis where the fixed link in a mechanism is changed while keeping the relative motion between the other links unchanged. This process results in a different mechanism with unique motion characteristics, but all the inversions belong to the same kinematic chain.

It is an essential concept in mechanical design, as it helps in deriving multiple mechanisms from a single kinematic chain to perform different tasks.

Inversions of a traditional 4 bar mechanism :

This is the common configuration , input is given to the yellow link and out put taken at the purple link.

Input given at the blue link and output is taken at the green link .

This will result in the two links (green and blue) completing full rotation hence crank.

Input is given to yellow link and output is taken at the purple link but the frame is inverted.

This will result in two rockers which will not complete full rotation

Categories: : Mechanism and Machine design