Module 2 : Robots mechanisms
Lecture 5 : Manipulators Mechanisms-I
Parallel Chains
 

Figure5.2.1

 

  
1) Stewart platform: Here 2 rings top & bottom are connected together through prismatic links and having ball & socket joint at bottom and hooks joint at top. Figure 5.2.1 beside. Stewart platform finds application in aircraft simulator where pilots are trained
 
 

Applying Grublers criterion for closed chains,

N=no of links=1

Js=no of spherical joints=6

Jh= no of hook's joint=6

Jr= no of revolute joint=0

Jp= no of prismatic joints=6

DOF = F=6(l-n-1) + S fi

Where l= no. of links

N= no of joints

fi = DOF with ith joint

Therefore, F = 6(14-18-1) + 36 = 6
   
1