| Compared with the serial mechanism, 6-dof parallel mechanism has a series of outstanding advantages, such as stiffness, structural stability, carrying capacity and higher control precision and so on, so they are applied to industrial production, aerospace, scientific experiments and other fields. But now for their control, we mostly study their motion control, and have relatively little research on direct control of the output power. With the increasingly application of 6-dof parallel mechanism and the strong coupling of themselves, it is necessary to control the output force with intelligent control strategy.Based on studied the force model of 6-SPS parallel mechanism and platform single-degree of freedom output force control method and finite element simulation, the paper studies the advantages of fuzzy PID control strategy on the force control of parallel mechanism compared with traditional PID control strategy. Specific contents are as follows:By the research of the force model, the paper deduces the output force formula of 6-dof parallel mechanism, analyzes the influence factors of output power and also gives the examples of single cylinder force solution of Stewart platform, and analyzes the platform single-degree of freedom output force control method.The paper use Solidworks and build the three-dimensional solid model of the 6-SPS parallel mechanism. Based on the gridding plot method, the finite element analysis about the single hydraulic cylinder and whole parallel mechanical is carried out by using the software COSMOSWorks. The nephograms of stress, displacement and strain are created, so the danger sections are obtained. Finally the paper gives the finite element analysis of vibration frequency on the whole system.The paper designed fuzzy PID controller which is suited for the requirement, and it sets various parameters. Single-cylinder force control system model and the transfer function are built, and the control block diagram is given. It establishes the simulation model of the single-cylinder force control system and platform output force of a single degree of freedom control system, by using MATLAB/Simulink as a simulation tool, it compared simulation research on the fuzzy PID control and traditional PID control in the cylinder output force control and platform output force control of single-degree of freedom, and analyzed a variety of factors in the force control. Then combined with AMESim/MATLAB simulation method, from another angle, gets more accurate simulation to the effects of fuzzy PID controller. |
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