Effect of Different Positions of Kinematic Pairs on Parallel Mechanism

The kinematics and statics properties of the2T1R3-SPR and 3-RPS fiexlble parallel mechanisms for the chip packages were analyzed and compared. The screw theory was applied to analyze kinematics. For the statics analysis,the equivalent binding force and driving force was analyzed according to screw analysis approach, and the equivalent balance equation was listed under external load. The theory was calculated using Matlab software. Through modeling by Solidworks and Adams kinematics simulation, the correctness of the theoretical calculation was verified. Our results showed that the binding force have different impact on the 3-SPR and 3-RPS parallel mechanism since the kinematic pairs position was different. When the 3-SPR parallel mechanism restricts the binding force for the fixed platform, there was less disturbance by the binding force and less deformation of the branched chain, comparing to these when the 3-RPS parallel mechanism restricts the moving platform. 3-SPR parallel mechanism showed better stability and better mechanical properties, which can satisfy the higher precision application in the field of chip packaging, embossing and other high precision engineering. Our study provided a theoretical reference to the research of flexible mechanism.