A novel redundantly actuated parallel machine tool was introduced. The inverse kinematic of 5-UPS/PRPU PMT with redundant actuation was analysed and the driven force of redundant actuation limb was planned. The force/position hybrid control strategy and dynamic differential calculation control strategy were proposed. Then the experiment of evaluating dynamics in the position control mode and in the force/position hybrid control was carried out respectively. The experiment shows that, the force/position hybrid control can improve driven torque of each limb better, balance the load of each limb and is of great help for enhance the dynamic performance of entire PMT.
The hardware control system of the 5-UPS/PRPU PMT (parallel machine tool) with redundant actuation was reconstructed to realize its hybrid force/position control, which was based on the primary “IPC+PMAC motion controller” system mode. Meanwhile, more perfect open type PMT control platform was constructed. Visual Basic language was used to realize the force servo control of the redundant limb and the relevant experiment was completed in the primary CNC system, combining with the PAMC motion controller library function. The results show that the force servo control strategy is exact and the newly designed hardware control system is effective, these results also provide feasible hardware basis and control method to realize the hybrid force/position control.
Graphene nanoplatelet(GN)/ Magnetite compound powders with magnetite nano-particles coated on the surface of graphite sheets has been successfully prepared by the wet-chemical co-precipitation. The effects of reaction temperature and mole ratio of Fe2+/Fe3+ on ultimate products were investigated. It has been found that excellent magnetite/GN compound powders were obtained at 30 °C with the Fe2+/Fe3+ mole ratio of 5:1. The composition, structure and the electric and magnetic properties of products were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, vibrating-sample magnetometer and four-point probe resistivity measurement.The compound powders have also exhibited the ferromagnetic properties at room temperature.
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