Each joint of a hydraulic-driven legged robot adopts a highly integrated hydraulic drive unit(HDU),which features a high power-weight ratio.However,most HDUs are throttling-valve-controlled cylinder systems,which exhi...Each joint of a hydraulic-driven legged robot adopts a highly integrated hydraulic drive unit(HDU),which features a high power-weight ratio.However,most HDUs are throttling-valve-controlled cylinder systems,which exhibit high energy losses.By contrast,pump control systems offer a high efficiency.Nevertheless,their response ability is unsatisfactory.To fully utilize the advantages of pump and valve control systems,in this study,a new type of pump-valve compound drive system(PCDS)is designed,which can not only effectively reduce the energy loss,but can also ensure the response speed and response accuracy of the HDUs in robot joints to satisfy the performance requirements of robots.Herein,considering the force control requirements of energy conservation,high precision,and fast response of the robot joint HDU,a nonlinear mathematical model of the PCDS force control system is first introduced.In addition,pressure-flow nonlinearity,friction nonlinearity,load complexity and variability,and other factors affecting the system are considered,and a novel force control method based on quantitative feedback theory(QFT)and a disturbance torque observer(DTO)is designed,which is denoted as QFT-DTOC herein.This method improves the control accuracy and robustness of the force control system,reduces the effect of the disturbance torque on the control performance of the servo motor,and improves the overall force control performance of the system.Finally,experimental verification is performed using the PCDS performance test platform.The experimental results and quantitative data show that the QFT-DTOC proposed herein can significantly improve the force control performance of the PCDS.The relevant force control method can be used as a bottom-control method for the hydraulic servo system to provide a foundation for implementing the top-level trajectory planning of the robot.展开更多
为解决风电机组在风电功率平抑和故障穿越2方面的不足,针对基于混合储能的直驱风力发电系统,提出一种同时兼顾风电功率平抑和故障穿越的复合功率控制策略。一方面,提出具有功率误差反馈环的改进型二阶滤波功率分配方法,实时修正超级电...为解决风电机组在风电功率平抑和故障穿越2方面的不足,针对基于混合储能的直驱风力发电系统,提出一种同时兼顾风电功率平抑和故障穿越的复合功率控制策略。一方面,提出具有功率误差反馈环的改进型二阶滤波功率分配方法,实时修正超级电容和蓄电池储能的功率响应指令,提高目标功率分配精度的同时改善跟踪控制效果,实现风电功率平抑的同时延长储能介质使用寿命;另一方面,提出网侧变流器(grid side convertor,GSC)和混合储能共同作用的复合功率控制策略,实时修正各控制量的功率响应指令并快速清除直流母线上的冗余功率,提高风电机组的故障穿越能力,使风电系统基本不受电网故障的影响。展开更多
基金Supported by National Excellent Natural Science Foundation of China(Grant No.52122503)Hebei Provincial Natural Science Foundation of China(Grant No.E2022203002)+2 种基金The Yanzhao’s Young Scientist Project of China(Grant No.E2023203258)Science Research Project of Hebei Education Department of China(Grant No.BJK2022060)Hebei Provincial Graduate Innovation Funding Project of China(Grant No.CXZZSS2022129).
文摘Each joint of a hydraulic-driven legged robot adopts a highly integrated hydraulic drive unit(HDU),which features a high power-weight ratio.However,most HDUs are throttling-valve-controlled cylinder systems,which exhibit high energy losses.By contrast,pump control systems offer a high efficiency.Nevertheless,their response ability is unsatisfactory.To fully utilize the advantages of pump and valve control systems,in this study,a new type of pump-valve compound drive system(PCDS)is designed,which can not only effectively reduce the energy loss,but can also ensure the response speed and response accuracy of the HDUs in robot joints to satisfy the performance requirements of robots.Herein,considering the force control requirements of energy conservation,high precision,and fast response of the robot joint HDU,a nonlinear mathematical model of the PCDS force control system is first introduced.In addition,pressure-flow nonlinearity,friction nonlinearity,load complexity and variability,and other factors affecting the system are considered,and a novel force control method based on quantitative feedback theory(QFT)and a disturbance torque observer(DTO)is designed,which is denoted as QFT-DTOC herein.This method improves the control accuracy and robustness of the force control system,reduces the effect of the disturbance torque on the control performance of the servo motor,and improves the overall force control performance of the system.Finally,experimental verification is performed using the PCDS performance test platform.The experimental results and quantitative data show that the QFT-DTOC proposed herein can significantly improve the force control performance of the PCDS.The relevant force control method can be used as a bottom-control method for the hydraulic servo system to provide a foundation for implementing the top-level trajectory planning of the robot.
文摘为解决风电机组在风电功率平抑和故障穿越2方面的不足,针对基于混合储能的直驱风力发电系统,提出一种同时兼顾风电功率平抑和故障穿越的复合功率控制策略。一方面,提出具有功率误差反馈环的改进型二阶滤波功率分配方法,实时修正超级电容和蓄电池储能的功率响应指令,提高目标功率分配精度的同时改善跟踪控制效果,实现风电功率平抑的同时延长储能介质使用寿命;另一方面,提出网侧变流器(grid side convertor,GSC)和混合储能共同作用的复合功率控制策略,实时修正各控制量的功率响应指令并快速清除直流母线上的冗余功率,提高风电机组的故障穿越能力,使风电系统基本不受电网故障的影响。
