This paper proposed a type of new parallel tilter with four degrees-of-freedom, whose moving platform has three rotations and one translation. The coordinate transformation is adopted to establish the position and velocity kinematics equation of the tilter. Simulation result indicated that the moving platform can move according to the set law by modifying the displacement of the piston rod in active limb.

According to the configuration theory of the parallel manipulator with a few degree of freedom (DOF), the paper adopted 2PSU-U mechanism to design a new parallel tilter with 2 DOF, which has such advantages as strong bearing capacity, high precision and kinematic decoupling. It used the coordinate transformation to establish the position and velocity equations of the tilter, and also used the instance to make kinematic simulation, whose result indicated that the roll and pitch angle of the moving platform can vary according to the set motion law by driving two sliders of the main moving branched chains.

According to the kinematics equation of the test tilter for the optical landing aid system, the velocity Jacobi matrix of the tilter is established. The determinant and the condition number of Jacobi matrix based on the numeric analysis in the preset workspace, as the evaluating indicator of the singularity and the dexterity. Simulation result indicates that there is no singularity in the tilter workspace because the determinant of the matrix is not equal to zero, and the tilter has higher rotary dexterity due to the smaller condition number of the rotational velocity Jacobi matrix. At the same time, the tilter has isotropy and the best dexterity in the vertical motion direction due to the condition number of the linear velocity Jacobi matrix is equal to 1.

Stress in the interface of contacts was calculated applying finite element software/ABAQUS, with which the Ruiz fretting damage parameter was obtained and the location for crack formation was found. A new model for predicting fretting fatigue life has been presented based on friction work. The rationality and effectiveness of the model were validated according to the contrast of experiment life and predicting life. At last influence factor on fretting fatigue life of aerial aluminum alloy LY12CZ was investigated with the model. The results revealed that fretting fatigue life decreased monotonously with the increasing of normal load and then became constant at higher pressures. At low normal load, fretting fatigue life was found to increase with increase in the pad radius. At high normal load, however, the fretting fatigue life remained almost unchanged with changes in the fretting pad radius. The bulk stress amplitude had the dominant effect on fretting fatigue life. The fretting fatigue life diminished as the bulk stress amplitude increased.

One type of spatial new parallel mechanism with two degree of freedom is proposed.. The position and velocity analytic equation are constructed based on the coordinate transformations. Finally, the singular configuration of the tilter is analyzed by the forward and the inverse Jacobian matrix.