Kinematic and dynamic analysis of a 2DOF parallel robot arm for wind turbine blade fatigue testing

In response to the issues of low efficiency and significant impact on blade intrinsic frequency posed by the current biaxial resonance blade fatigue testing method, an innovative dynamic characterization method based on a 2-DOF (two-degree-of-freedom) planar parallel testing device is proposed in this paper. Firstly, the kinematic forward and inverse solution equations of the mechanism are established by scrutinizing the inherent positional relationships that govern its operation. The velocity Jacobian matrix is derived, and three types of singularities prevalent in the mechanism are analyzed. Secondly, based on the kinematics of the mechanism, an analysis of its workspace is undertaken to subsequently determine the range of its motion. Thirdly, by applying the Lagrange equations, the kinetic model of the mechanism is established, which can capture the dynamic interplay of forces and accurately calculate the changes in angular displacement, angular velocity, and angular acceleration of the active joint. Finally, a virtual prototype model and kinematics simulation are conducted based on the mechanism dimensions and assembly mode. The results show that the angular velocity, angular acceleration, and torque of the active joint all demonstrate smooth and uninterrupted curves that align with the actual testing trajectories, confirming the accuracy and effectiveness of our approach.