Design And Analysis Of Tracking Parallel Mechanism

Surveying the rapid development of mechanical industry, the linkage number and complexity of mechanism keeps increasing and the diffculty and period of mechanism design as well. Machinary develops in the way of high-speed, high-precise and heavy-loaded.A brand new 2-DOF spherical fixed-point 5-bar mechanism has been used in the tracking parallel mechanism design. It has many advantages such as compactness, few linkages, flexibility and easy control. It just need a pair of parallel 4-bar linkage to drive the end-effecter, so it is fit for the situation of heavy loaded and high-precise. Due to these excellences, it can be applied in different situations, such as calibration and ranging of work pieces under the high temperature or high pressure in the industry; human-computer interaction in the joystick for household use; locating cutter postion in the surgery for medical purpose; eye ball motion control for the humanoid robot etc. It seems that 2-DOF spherical fixed-point 5-bar mechanism has extrodinary future in agriculture, medicine, domestic and even military.The paper’s study has several key points as following:1. Kinematics of tracking parallel mechanismSet up coordinate system for the kinematic model according to the principle of robotics and solve the kinematics positve solution and negative solution and Jaccobi Matrix of mechanism by the D-H method. Validate the result with the simulation by the UG.2. Kinetics of tracking parallel mechanismSince we just have the dynamic balance research method of planar mechanism, we generaize principle of inertial force and inertial moment and apply it into sovling the dynamic balance problem of the spatial 5-bar linkage mechanism. We calculate mass moment of the whole parallel mechanism, and make it constant, that means that the center of mass of the whole parallel mechanism keeps static. The balance condition of inertial force can be got. Then we calculate angular momentum of the whole parallel mechanism, and get the formular of inertial moment. The analysis of dynamic balance condition will be theretical basis for the design. At last the driving moment of tracking parallel mechanism in the inertial coordinate system has been calculated and the relationship between input condition and driving moment has been obtained.3. FEA of of tracking parallel mechanismWith the help of high efficient FEA software NASTRAN NX, we perform the systematic analysis of intensity, siffness, strain distribution, modal and harmonic response for the tracking parallel mechanism to secure the stability of working performence. The purpose of FEA is to validate the component under the special environment and working condition and to make sure that they are all within the safty range of allowable stress, strain and strength. In addition modal analysis is used to avoid the consistence between nature frequency of the component and outside forced frequency, such as wind or motors.4. 3D human-computer interaction of tracking parallel mechanismThe paper also use Visual C++ OpengGL interface to support the control research of the tracking parallel mechanism. It also helps us to understand the shape and limits of the workspace of the mechanism with offering the virtual reality enviorment. It will reveal the reasonable motion and control algorithm. It will also offer an effective method to validate the collipse or the interface of the mechanism so as to solve the common problems during the designing, manufacturing and operation.