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Optimization of a crossbar parallel machine tool based on workspace and dexterity
Fang Xifeng,Zhang Sichong,Xu Qinhuan,Wang Tongyue,Liu Yuanwei,Chen Xiaogang 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.8
Increasing workspace and improving dexterity are important tasks for the design of parallel machine tools. The workspace of a crossbarparallel machine tool with constraints is obtained by using a 3D search method based on inverse kinematics. The new Jacobian matrixof the machine is also derived by using the natural coordinate method. Dexterity distribution of the machine tool is obtained on the basisof the workspace and the new Jacobian matrix. Influences of the structural parameters on the workspace volume index (WVI) and globaldexterity index (GDI) are analyzed. Structural optimization is conducted by treating the WVI and GDI as the global optimization goals. Unlike the initial data, the optimized results increased by 0.43 and 0.34 times.
MODELING AND CONTROL OF A HIGH SPEED ON/OFF VALVE ACTUATOR
Jigen Fang,Xifeng Wang,Jinjun Wu,Shuai Yang,Liang Li,Xiang Gao,Yue Tian 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.6
Accurate electromagnetic force control in a high speed on/off valve actuator (HSVA) can improve the performance of a vehicle braking system, and an accurate theoretical model is the key to smoothly controlling the high speed on/off valve. Therefore, a nonlinear model of an HSVA is proposed in this paper. Three subsystems are modeled as a spring/ mass/damper system, a nonlinear resistor/inductor system and a multiwall heat transfer system, respectively. Then, a slidingmodel controller combined with a sliding-model observer is designed to adjust the electromagnetic force for an accurate HSVA state control, taking the effect of the coil heating into account. The feasibility of the three submodels and the slidingmodel controller are verified by comparing the simulation results with the experimental results obtained on a test bench. Our study shows that the three subsystems are coupled to one another through resistance, displacement, and temperature. When the excitation voltage exceeds 9 V, the coil temperature can reach more than 150 degrees Celsius within 300 s, and the electromagnetic force decreases by approximately 30 %. However, by applying the above control strategy, the electromagnetic force can also be stable, fluctuating within 5 % even if the temperature of the coil rises to the thermal equilibrium temperature.