This study proposes an accurate dead zone compensation control method for electro-hydrostatic actuators(EHAs)under low-speed conditions.Specifically,the nonlinear dead zone characteristics under low-speed conditions a...This study proposes an accurate dead zone compensation control method for electro-hydrostatic actuators(EHAs)under low-speed conditions.Specifically,the nonlinear dead zone characteristics under low-speed conditions are summarized based on numerous EHA experiments.An adaptive compensation function(ACF)is then constructed for the dead zone.Next,this study proposes an adaptive dead zone compensation control method for EHAs by integrating the ACF with a virtual decomposition controller(VDC)based on the established EHA model.The stability of the proposed control method is also proven.Finally,the proposed control method is verified using an EHA platform.The test results show that the dead zone trajectory tracking errors of EHAs are significantly reduced when combined with the ACF.Furthermore,since most EHAs are controlled by adjusting the motor speed,the method presented in this study is simpler and easier to use than methods that employ flow compensation.展开更多
The hydraulic exoskeleton is one research hotspot in the field of robotics,which can take heavy load due to the high power density of the hydraulic system.However,the traditional hydraulic system is normally centraliz...The hydraulic exoskeleton is one research hotspot in the field of robotics,which can take heavy load due to the high power density of the hydraulic system.However,the traditional hydraulic system is normally centralized,inefficient,and bulky during application,which limits its development in the exoskeleton.For improving the robot's performance,its hydraulic actuating system should be optimized further.In this paper a novel hydraulic actuating system(HAS)based on electric-hydrostatic actuator is proposed,which is applied to hip and knee joints.Each HAS integrates an electric servo motor,a high-speed micro pump,a specific tank,and other components into a module.The specific parameters are obtained through relevant simulation according to human motion data and load requirements.The dynamic models of the HAS are built,and validated by the system identification.Experiments of trajectory tracking and human-exoskeleton interaction are carried out,which demonstrate the proposed HAS has the ability to be applied to the exoskeleton.Compared with the previous prototype,the total weight of the HAS in the robot is reduced by about 40%,and the power density is increased by almost 1.6 times.展开更多
As a reinforcement technology that improves load-bearing ability and prevents injuries,assisted exoskeleton robots have extensive applications in freight transport and health care.The perception of gait information by...As a reinforcement technology that improves load-bearing ability and prevents injuries,assisted exoskeleton robots have extensive applications in freight transport and health care.The perception of gait information by such robots is vital for their control.This information is the basis for motion planning in assistive and collaborative functions.Here,a wearable gait recognition sensor system for exoskeleton robots is presented.Pressure sensor arrays based on laser-induced graphene are developed with flexibility and reliability.Multiple sensor units are integrated into an insole to detect real-time pressure at key plantar positions.In addition,the circuit hardware and the algorithm are designed to reinforce the sensor system with the capability of gait recognition.The experimental results show that the accuracy of gait recognition by the proposed system is 99.85%,and the effectiveness of the system is further verified through testing on an exoskeleton robot.展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.51890883,U2141209)1912 Project Foundation。
文摘This study proposes an accurate dead zone compensation control method for electro-hydrostatic actuators(EHAs)under low-speed conditions.Specifically,the nonlinear dead zone characteristics under low-speed conditions are summarized based on numerous EHA experiments.An adaptive compensation function(ACF)is then constructed for the dead zone.Next,this study proposes an adaptive dead zone compensation control method for EHAs by integrating the ACF with a virtual decomposition controller(VDC)based on the established EHA model.The stability of the proposed control method is also proven.Finally,the proposed control method is verified using an EHA platform.The test results show that the dead zone trajectory tracking errors of EHAs are significantly reduced when combined with the ACF.Furthermore,since most EHAs are controlled by adjusting the motor speed,the method presented in this study is simpler and easier to use than methods that employ flow compensation.
基金Supported by Nati onal Key R&D Program of China(Grant No.2018YFB1305400,2018YFB1305402)National Natural Science Foundation of China(Grant No.518902883)Fun dame ntal Resea rch Funds for the Central Universities(Grant No.2018XZZX001-04).
文摘The hydraulic exoskeleton is one research hotspot in the field of robotics,which can take heavy load due to the high power density of the hydraulic system.However,the traditional hydraulic system is normally centralized,inefficient,and bulky during application,which limits its development in the exoskeleton.For improving the robot's performance,its hydraulic actuating system should be optimized further.In this paper a novel hydraulic actuating system(HAS)based on electric-hydrostatic actuator is proposed,which is applied to hip and knee joints.Each HAS integrates an electric servo motor,a high-speed micro pump,a specific tank,and other components into a module.The specific parameters are obtained through relevant simulation according to human motion data and load requirements.The dynamic models of the HAS are built,and validated by the system identification.Experiments of trajectory tracking and human-exoskeleton interaction are carried out,which demonstrate the proposed HAS has the ability to be applied to the exoskeleton.Compared with the previous prototype,the total weight of the HAS in the robot is reduced by about 40%,and the power density is increased by almost 1.6 times.
基金supported by the STI 2030—Major Projects(2022ZD0208601)the National Natural Science Foundation of China(52305077,52105593)+1 种基金the Zhejiang Provincial Natural Science Foundation of China(LDQ24E050001)the“Pioneer”and“Leading Goose”R&D Program of Zhejiang(2023C01051,2023C03007).
文摘As a reinforcement technology that improves load-bearing ability and prevents injuries,assisted exoskeleton robots have extensive applications in freight transport and health care.The perception of gait information by such robots is vital for their control.This information is the basis for motion planning in assistive and collaborative functions.Here,a wearable gait recognition sensor system for exoskeleton robots is presented.Pressure sensor arrays based on laser-induced graphene are developed with flexibility and reliability.Multiple sensor units are integrated into an insole to detect real-time pressure at key plantar positions.In addition,the circuit hardware and the algorithm are designed to reinforce the sensor system with the capability of gait recognition.The experimental results show that the accuracy of gait recognition by the proposed system is 99.85%,and the effectiveness of the system is further verified through testing on an exoskeleton robot.
