| The parallel mechanism has been applied to the radar antenna field due to its strong bearing capacity and small accumulated error.Compared with the 6-DOF parallel mechanism,the number of branches and components of the less-degree-of-freedom parallel mechanism is reduced,the structure is simpler,the manufacturing cost is lower,and the high reliability is easily ensured.Considering the economy of the product and the reliability of the antenna movement,the research on the parallel antenna with less degree of freedom is of great significance.Unlike conventional fixed-radar antennas,vehicle-mounted antennas need to be moved along with the vehicle,and the working environment is mostly outdoors,and the conditions are complicated.The effect of the unique working condition of the vehicle antenna on the directional precision of the antenna can’t be ignored.In view of this,the 3-RSR(R denotes the revolute pair,S denotes the spherical pair)is selected as the research object by the configuration optimization,in this paper.Considering the actual working conditions of the vehicle,establish the dynamic model with the goal of maximizing the natural frequency of the machine,Dynamic design and optimization of structural parameters of mechanism.The main contents of this paper are as follows :Considering the work requirements of antenna pitching、azimuthal rotation and collection.Select 3-RSR,PU-2UPS and 3-RPS(P denotes the moving pair,U denotes the Hook hinge)three 2R1 T parallel mechanism as an antenna mechanism options.Analyzing the position inverse solution、the working space and the drive torque under the specified trajectory of each mechanism,and make a comprehensive comparison of their performance.Based on the Lagrange equation method,the dynamics model of the 3-RSR parallel antenna mechanism were established when the base was fixed and moving respectively,and obtained the dynamic equations of the mechanism under corresponding conditions.Solving the mechanism dynamic model numerically,and drawing the change curve of mechanism driving torque with time under the specified movement trajectory of the antenna,and the influence of base movement on the driving torque of vehicle antenna mechanism was analyzed.The optimization goal is to maximize the overall natural frequency of the antenna mechanism,the optimization mathematical model of 3-RSR antenna mechanism were established,the parameters of 3-RSR antenna are optimized by genetic algorithm,and verify the effectiveness of the results by the comparison between the before and after mechanism optimization.The mathematical model of wind load,snow load and random excitation conditions of the antenna mechanism was established.Combining the virtual prototype model of 3-RSR parallel antenna mechanism,the dynamic simulation of the mechanism is carried out under both the accuracy and the drivability. |
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