Numerical simulation and control of self- propelled swimming of two- and three-dimensional biomimetic fish school in a viscous flow are investigated. With a parallel computational fluid dynamics package for the two- a...Numerical simulation and control of self- propelled swimming of two- and three-dimensional biomimetic fish school in a viscous flow are investigated. With a parallel computational fluid dynamics package for the two- and three-dimensional moving boundary problem, which combines the adaptive multi-grid finite volume method and the methods of immersed boundary and volume of fluid, it is found that due to the interactions of vortices in the wakes, without proper control, a fish school swim with a given flap- ping rule can not keep the fixed shape of a queue. In order to understand the secret of fish swimming, a new feedback con- trol strategy of fish motion is proposed for the first time, i,e., the locomotion speed is adjusted by the flapping frequency of the caudal, and the direction of swimming is controlled by the swinging of the head of a fish. Results show that with this feedback control strategy, a fish school can keep the good order of a queue in cruising, turning or swimming around circles. This new control strategy, which separates the speed control and direction control, is important in the construction of biomimetic robot fish, with which it greatly simplifies the control devices of a biomimetic robot fish.展开更多
针对三相PWM(pulse width modulation)整流器预测直接功率控制(predictive direct power control,PDPC)策略中,数字处理过程存在的延迟问题,设计两步预测方法消除延迟,并设计反馈校正环节对传统PDPC策略中参考功率不准确的问题进行修正...针对三相PWM(pulse width modulation)整流器预测直接功率控制(predictive direct power control,PDPC)策略中,数字处理过程存在的延迟问题,设计两步预测方法消除延迟,并设计反馈校正环节对传统PDPC策略中参考功率不准确的问题进行修正,消除实际功率与参考功率之间存在的偏差.另外,在三相PWM整流器中,网压传感器使整个系统变得更复杂且耗费成本,因此采用改进型二阶广义积分器(second-order generalized integrator,SOGI)产生同频率的正交信号估算电网电压,并将基于改进型SOGI的无网压传感器算法应用于优化后的PDPC策略中.在仿真平台对所提方法进行仿真,结果表明所提方法消除了功率跟踪偏差,准确估算了电网电压.通过对比传统与优化后的PDPC策略仿真结果,验证了所提方法的有效性.展开更多
基金supported by the National Natural Science Foundation of China(10172095 and 10672183)
文摘Numerical simulation and control of self- propelled swimming of two- and three-dimensional biomimetic fish school in a viscous flow are investigated. With a parallel computational fluid dynamics package for the two- and three-dimensional moving boundary problem, which combines the adaptive multi-grid finite volume method and the methods of immersed boundary and volume of fluid, it is found that due to the interactions of vortices in the wakes, without proper control, a fish school swim with a given flap- ping rule can not keep the fixed shape of a queue. In order to understand the secret of fish swimming, a new feedback con- trol strategy of fish motion is proposed for the first time, i,e., the locomotion speed is adjusted by the flapping frequency of the caudal, and the direction of swimming is controlled by the swinging of the head of a fish. Results show that with this feedback control strategy, a fish school can keep the good order of a queue in cruising, turning or swimming around circles. This new control strategy, which separates the speed control and direction control, is important in the construction of biomimetic robot fish, with which it greatly simplifies the control devices of a biomimetic robot fish.
文摘针对三相PWM(pulse width modulation)整流器预测直接功率控制(predictive direct power control,PDPC)策略中,数字处理过程存在的延迟问题,设计两步预测方法消除延迟,并设计反馈校正环节对传统PDPC策略中参考功率不准确的问题进行修正,消除实际功率与参考功率之间存在的偏差.另外,在三相PWM整流器中,网压传感器使整个系统变得更复杂且耗费成本,因此采用改进型二阶广义积分器(second-order generalized integrator,SOGI)产生同频率的正交信号估算电网电压,并将基于改进型SOGI的无网压传感器算法应用于优化后的PDPC策略中.在仿真平台对所提方法进行仿真,结果表明所提方法消除了功率跟踪偏差,准确估算了电网电压.通过对比传统与优化后的PDPC策略仿真结果,验证了所提方法的有效性.
