Based on the analysis of the mechanism of wire tension control by using torque motors in the multi-wire saw machining process, some mathematical models of a tension control system are studied, and an adaptive algo- ri...Based on the analysis of the mechanism of wire tension control by using torque motors in the multi-wire saw machining process, some mathematical models of a tension control system are studied, and an adaptive algo- rithm is designed for controlling the wire tension. In this algorithm of tension control, the rotation speeds and waving angle of motors are measured and fed back to the controller, and the NLMS（ normalized least mean squares） algorithm is used to calculate the adaptive correction value and control the wire tension accurately. The computer simulation results in Matlab software validate the high accuracy for controlling the system of the wire tension with the NLMS algorithm in the multi-wire saw machining process.展开更多
Oscillatory failure cases(OFC)detection in the fly-by-wire(FBW)flight control system for civil aircraft is addressed in this paper.First,OFC is ranked four levels:Handling quality,static load,global structure fatigue ...Oscillatory failure cases(OFC)detection in the fly-by-wire(FBW)flight control system for civil aircraft is addressed in this paper.First,OFC is ranked four levels:Handling quality,static load,global structure fatigue and local fatigue,according to their respect impact on aircraft.Second,we present voting and comparing monitors based on un-similarity redundancy commands to detect OFC.Third,the associated performances,the thresholds and the counters of the monitors are calculated by the high fidelity nonlinear aircraft models.Finally,the monitors of OFC are verified by the Iron Bird Platform with real parameters of the flight control system.The results show that our approach can detect OFC rapidly.展开更多
Waveform control method was commonly adopted to reduce the spatter of CO2 arc welding and improve the weld formation. It certainly would reduce the self-regulation ability of arc due to the adoption of segmented const...Waveform control method was commonly adopted to reduce the spatter of CO2 arc welding and improve the weld formation. It certainly would reduce the self-regulation ability of arc due to the adoption of segmented constant current control which especially led to arc＂ blowout with the abrupt change oat＂ arc＂ length or downward welding. Therefore alterative wire-feed system based on arc voltage negative feedback was put forward to improve the .stability of arc＂ length in this paper. Double closed-loop and double fuzzy P1 regulation were adopted in this system. Fuzzy control of induced voltage was adopted in the inner-loop which improved the stability and fast response of wire-feed system. Fuzz）＂ control of arc＂ voltage negative feedback was used in the outer-loop whose output .served as the input of negative feedback regulation of inner-loop induced voltage. This method could remain arc＂ length and weld penetration unchan, ged on the basils of reducing spatter and improving formation and it was proved by downward welding tests.展开更多
On the tasis of study in the mathematical model of 3-dimensional ruled surface (RS),this paper introduces a new concept of distance paramcter (DP) and also puts forward that themethod of modeling a RS depends on not o...On the tasis of study in the mathematical model of 3-dimensional ruled surface (RS),this paper introduces a new concept of distance paramcter (DP) and also puts forward that themethod of modeling a RS depends on not only two boundary curves but also DP. According toabove theory, the formulas to calculate corresponding point coordinates to any kind of top and bot-tom profile of a workpiece and formulas to calcuate the maximum inclination angle of ruling linehave been obtained. Then a different top and bottom RS mathining method including profile withline-are combination as well as parametric curves has been achieved by 4-axes simultancous con-trol programming proposed.展开更多
On-line measurement and control method of moving wire vibration are developed. The response measurement of the wire is indirectly accomplished by 'vibration transfer method ' and active con- trol is carried o...On-line measurement and control method of moving wire vibration are developed. The response measurement of the wire is indirectly accomplished by 'vibration transfer method ' and active con- trol is carried out on the vibration receiving body by piezoelectric ceramics. The fundamental princi- ples of measurement and control are stated and experimental results are presented.展开更多
A deformation measurement method of interframe displacement was proposed in this paper. By online monitoring the shape di- mensions of both the deformation zone and its adjacent zone by machine vision, the initial and...A deformation measurement method of interframe displacement was proposed in this paper. By online monitoring the shape di- mensions of both the deformation zone and its adjacent zone by machine vision, the initial and terminative positions of deformation were dynamically identified during dieless drawing, and the global monitoring and online closed-loop control of the deformation zone were achieved. The dieless drawing process was systematically carried out on NiTi shape memory alloy wires. It is shown that the deformation measurement method of interframe displacement can track the axial displacement of the wires, but this cannot be achieved by traditional machine vision. The initial and terminative positions of deformation can be accurately identified by this method. The proposed rectifying control technology can effectively decrease the wire diameter fluctuation during dieless drawing, that is, the standard deviation of the wire diameter fluctuation could be decreased fi＇om 0.30 to 0.08 mm after three passes of dieless drawing, indicating that the control system has a good rectifying ability.展开更多
针对线控转向(steer by wire, SBW)系统主动转向时面临的系统参数不确定性、轮胎回正力矩阻碍、转向电机电磁特性耦合等非线性干扰问题,提出一种自适应抗扰转角控制策略。采用径向基函数神经网络和鲁棒滑模理论设计外环转角控制器,自适...针对线控转向(steer by wire, SBW)系统主动转向时面临的系统参数不确定性、轮胎回正力矩阻碍、转向电机电磁特性耦合等非线性干扰问题,提出一种自适应抗扰转角控制策略。采用径向基函数神经网络和鲁棒滑模理论设计外环转角控制器,自适应补偿SBW系统参数不确定性和轮胎回正力矩阻碍。在内环电流控制器中引入线性自抗扰控制应对转向执行电机电磁特性耦合问题,提高SBW系统动态响应性能。仿真和硬件在环试验结果表明,设计的控制策略能够帮助SBW在多种工况中维持转角稳态跟随误差在1.5°内。展开更多
基金supported by the National Natural Science Fundproject (50775207)Key Laboratory of E & M (Zhejiang University of Technology) Open Fund project (2009EP017)
文摘Based on the analysis of the mechanism of wire tension control by using torque motors in the multi-wire saw machining process, some mathematical models of a tension control system are studied, and an adaptive algo- rithm is designed for controlling the wire tension. In this algorithm of tension control, the rotation speeds and waving angle of motors are measured and fed back to the controller, and the NLMS（ normalized least mean squares） algorithm is used to calculate the adaptive correction value and control the wire tension accurately. The computer simulation results in Matlab software validate the high accuracy for controlling the system of the wire tension with the NLMS algorithm in the multi-wire saw machining process.
文摘Oscillatory failure cases(OFC)detection in the fly-by-wire(FBW)flight control system for civil aircraft is addressed in this paper.First,OFC is ranked four levels:Handling quality,static load,global structure fatigue and local fatigue,according to their respect impact on aircraft.Second,we present voting and comparing monitors based on un-similarity redundancy commands to detect OFC.Third,the associated performances,the thresholds and the counters of the monitors are calculated by the high fidelity nonlinear aircraft models.Finally,the monitors of OFC are verified by the Iron Bird Platform with real parameters of the flight control system.The results show that our approach can detect OFC rapidly.
文摘Waveform control method was commonly adopted to reduce the spatter of CO2 arc welding and improve the weld formation. It certainly would reduce the self-regulation ability of arc due to the adoption of segmented constant current control which especially led to arc＂ blowout with the abrupt change oat＂ arc＂ length or downward welding. Therefore alterative wire-feed system based on arc voltage negative feedback was put forward to improve the .stability of arc＂ length in this paper. Double closed-loop and double fuzzy P1 regulation were adopted in this system. Fuzzy control of induced voltage was adopted in the inner-loop which improved the stability and fast response of wire-feed system. Fuzz）＂ control of arc＂ voltage negative feedback was used in the outer-loop whose output .served as the input of negative feedback regulation of inner-loop induced voltage. This method could remain arc＂ length and weld penetration unchan, ged on the basils of reducing spatter and improving formation and it was proved by downward welding tests.
文摘On the tasis of study in the mathematical model of 3-dimensional ruled surface (RS),this paper introduces a new concept of distance paramcter (DP) and also puts forward that themethod of modeling a RS depends on not only two boundary curves but also DP. According toabove theory, the formulas to calculate corresponding point coordinates to any kind of top and bot-tom profile of a workpiece and formulas to calcuate the maximum inclination angle of ruling linehave been obtained. Then a different top and bottom RS mathining method including profile withline-are combination as well as parametric curves has been achieved by 4-axes simultancous con-trol programming proposed.
文摘On-line measurement and control method of moving wire vibration are developed. The response measurement of the wire is indirectly accomplished by 'vibration transfer method ' and active con- trol is carried out on the vibration receiving body by piezoelectric ceramics. The fundamental princi- ples of measurement and control are stated and experimental results are presented.
基金financially supported by the National Basic Research Priorities Program of China (No.2011CB606300)the National Natural Science Foundation of China (Nos.50634010 and 50674008)+1 种基金the Program for New Century Excellent Talents in Chinese Universities(No.NCET-06-0083)the Universities Fundamental Research Foundation of the Ministry of Education, China (No.FRF-TP-10-002B)
文摘A deformation measurement method of interframe displacement was proposed in this paper. By online monitoring the shape di- mensions of both the deformation zone and its adjacent zone by machine vision, the initial and terminative positions of deformation were dynamically identified during dieless drawing, and the global monitoring and online closed-loop control of the deformation zone were achieved. The dieless drawing process was systematically carried out on NiTi shape memory alloy wires. It is shown that the deformation measurement method of interframe displacement can track the axial displacement of the wires, but this cannot be achieved by traditional machine vision. The initial and terminative positions of deformation can be accurately identified by this method. The proposed rectifying control technology can effectively decrease the wire diameter fluctuation during dieless drawing, that is, the standard deviation of the wire diameter fluctuation could be decreased fi＇om 0.30 to 0.08 mm after three passes of dieless drawing, indicating that the control system has a good rectifying ability.
文摘针对线控转向(steer by wire, SBW)系统主动转向时面临的系统参数不确定性、轮胎回正力矩阻碍、转向电机电磁特性耦合等非线性干扰问题,提出一种自适应抗扰转角控制策略。采用径向基函数神经网络和鲁棒滑模理论设计外环转角控制器,自适应补偿SBW系统参数不确定性和轮胎回正力矩阻碍。在内环电流控制器中引入线性自抗扰控制应对转向执行电机电磁特性耦合问题,提高SBW系统动态响应性能。仿真和硬件在环试验结果表明,设计的控制策略能够帮助SBW在多种工况中维持转角稳态跟随误差在1.5°内。
