Robot teleoperation plays an important role in industrial manufacturing in unknown and dangerous environments beyond human reach.In telerobotic manufacturing tasks,environmental interaction forces may vary significant...Robot teleoperation plays an important role in industrial manufacturing in unknown and dangerous environments beyond human reach.In telerobotic manufacturing tasks,environmental interaction forces may vary significantly from task to task.Therefore,it is crucial to provide operators with the specific proportional feedback of environmental interaction forces to enhance their environmental awareness and manipulation capabilities.However,variable time delays and various scales of environmental interaction force feedback seriously affect the system stability,which should be rigorously addressed when designing control parameters.To cope with these difficulties,a position and scaled force tracking control framework is proposed and the LyapunovKrasovskii theory is used to obtain a simple algebraic stability criterion with the scaling factor of the environmental interaction force feedback.In addition,a low-pass filter-based radial basis function neural network is designed to avoid the effect of the measurement noise and the sudden change of the non-passive environmental interaction force on the system stability.Compared with different controllers in various telerobotic manufacturing tasks such as heavy lifting,cutting,and polishing,our proposed method achieves better position and scaled force tracking performance.展开更多
This paper is devoted to the problem of modeling and adaptive motion/force tracking for a class of nonholonomic dynamic systems with affine constraints(NDSAC): a vertical wheel on a rotating table. Prior to the develo...This paper is devoted to the problem of modeling and adaptive motion/force tracking for a class of nonholonomic dynamic systems with affine constraints(NDSAC): a vertical wheel on a rotating table. Prior to the development of tracking controller,the dynamic model of the wheel in question is derived in a meticulous manner. A continuously differentiable friction model is also considered in the modeling. By exploiting the inherent cascade interconnected structure of the wheel dynamics, an adaptive motion/force tracking controller is presented guaranteeing that the trajectory tracking errors asymptotically converge to zero while the contact force tracking errors can be made small enough by tuning design parameters. Simulation results are provided to validate the effectiveness of the proposed tracking methodology.展开更多
Purpose–The purpose of this paper is to apply a intelligent algorithm to conduct the force tracking control for electrohydraulic servo system(EHSS).Specifically,the adaptive neuro-fuzzy inference system(ANFIS)is sele...Purpose–The purpose of this paper is to apply a intelligent algorithm to conduct the force tracking control for electrohydraulic servo system(EHSS).Specifically,the adaptive neuro-fuzzy inference system(ANFIS)is selected to improve the control performance for EHSS.Design/methodology/approach–Two types of input–output data were chosen to train the ANFIS models.The inputs are the desired and actual forces,and the output is the current.The first type is to set a sinusoidal signal for the current to produce the actual driving force,and the desired force is chosen as same as the actual force.The other type is to give a sinusoidal signal for the desired force.Under the action of the PI controller,the actual force tracks the desired force,and the current is the output of the PI controller.Findings–The models built based on the two types of data are separately named as the ANFIS I controller and the ANFIS II controller.The results reveal that the ANFIS I controller possesses the best performance in terms of overshoot,rise time and mean absolute error and show adaptivity to different tracking conditions,including sinusoidal signal tracking and sudden change signal tracking.Originality/value–This paper is the first time to apply the ANFIS to optimize the force tracking control for EHSS.展开更多
A modified Monte Carlo model of speckle tracking of shear wave propagation in scattering media is proposed. The established Monte Carlo model mainly concerns the variations of optical electric field and speckle. The t...A modified Monte Carlo model of speckle tracking of shear wave propagation in scattering media is proposed. The established Monte Carlo model mainly concerns the variations of optical electric field and speckle. The two- dimensional intensity distribution and the time evolution of speckles in different probe locations are obtained. The fluctuation of speckle intensity tracks the acoustic-radiation-force shear wave propagation, and especially the reduction of speckle intensity implies attenuation of shear wave. Then, the shear wave velocity is estimated quantitatively on the basis of the time-to-peak algorithm and linear regression processing. The results reveal that a smaller sampling interval yields higher estimation precision and the shear wave velocity is estimated more efficiently by using speckle intensity difference than by using speckle contrast difference according to the estimation error. Hence, the shear wave velocity is estimated to be 2.25 m/s with relatively high accuracy for the estimation error reaches the minimum （0.071）.展开更多
Compliant interaction control is a key technology for robots performing contact-rich manipulation tasks.The design of the compliant controller needs to consider the robot hardware because complex control algorithms ma...Compliant interaction control is a key technology for robots performing contact-rich manipulation tasks.The design of the compliant controller needs to consider the robot hardware because complex control algorithms may not be compatible with the hardware performance,especially for some industrial robots with low bandwidth sensors.This paper focuses on effective and easy-to-use compliant control algorithms for position/velocity-controlled robots.Inspired by human arm stiffness adaptation behavior,a novel variable target stiffness(NVTS)admittance control strategy is proposed for adaptive force tracking,in which a proportional integral derivative(PID)variable stiffness law is designed to update the stiffness coefficient of the admittance function by the force and position feedback.Meanwhile,its stability and force-tracking capability are theoretically proven.In addition,an impact compensator(Impc)is integrated into the NVTS controller to enhance its disturbance-suppression capability when the robot is subjected to strong vibration disturbances in complicated surface polishing tasks.The proposed controllers are validated through four groups of experimental tests using different robots and the corresponding results demonstrate that they have high-accuracy tracking capability and strong adaptability in unknown environments.展开更多
The control of single pneumatic muscle actuator is studied, as one basic partof research on the parallel-robot arthrosis actuated by pneumatic muscle actuators. Experimentsshow that a self-modified fuzzy-PID controlle...The control of single pneumatic muscle actuator is studied, as one basic partof research on the parallel-robot arthrosis actuated by pneumatic muscle actuators. Experimentsshow that a self-modified fuzzy-PID controller is obviously effective for its position servo and asimple PID controller is good for its force track.展开更多
Stiffness adjustment is an important feature of human arm control.The adaptive variable impedance control can adapt to the robotic stiffness,but may result in a large overshoot.In this paper,nonlinear impedance contro...Stiffness adjustment is an important feature of human arm control.The adaptive variable impedance control can adapt to the robotic stiffness,but may result in a large overshoot.In this paper,nonlinear impedance control is proposed for collaborative robotic grinding,where nonlinear force feedback is designed to compensate for the nonlinear stiffness of the environment.Thus,the interaction system can be linearization to ensure the system stability.Moreover,a target trajectory adaptation strategy is studied to ensure the force tracking requirement.Then,switching law between trajectory tracking and force tracking is proposed when the robot performs a complex grinding task.The stability of the switch control as well as the trajectory adaptation law is proved.Experiments are conducted in a robotic grinding test rig,where the robot is used to grind a turbine blade.Experimental results show that the nonlinear impedance control can obtain stable grinding force,and have better grinding quality than the linear impedance control.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.52188102,52105515,62373161)。
文摘Robot teleoperation plays an important role in industrial manufacturing in unknown and dangerous environments beyond human reach.In telerobotic manufacturing tasks,environmental interaction forces may vary significantly from task to task.Therefore,it is crucial to provide operators with the specific proportional feedback of environmental interaction forces to enhance their environmental awareness and manipulation capabilities.However,variable time delays and various scales of environmental interaction force feedback seriously affect the system stability,which should be rigorously addressed when designing control parameters.To cope with these difficulties,a position and scaled force tracking control framework is proposed and the LyapunovKrasovskii theory is used to obtain a simple algebraic stability criterion with the scaling factor of the environmental interaction force feedback.In addition,a low-pass filter-based radial basis function neural network is designed to avoid the effect of the measurement noise and the sudden change of the non-passive environmental interaction force on the system stability.Compared with different controllers in various telerobotic manufacturing tasks such as heavy lifting,cutting,and polishing,our proposed method achieves better position and scaled force tracking performance.
基金supported by the National Natural Science Foundation of China(6127309161403227+3 种基金61403228)the Ph.D.Programs Foundation of Ministry of Education of Chinathe Fundamental Research Funds for the Central Universities(KYLX15 0116)the Project of Taishan Scholar of Shandong Province of China
文摘This paper is devoted to the problem of modeling and adaptive motion/force tracking for a class of nonholonomic dynamic systems with affine constraints(NDSAC): a vertical wheel on a rotating table. Prior to the development of tracking controller,the dynamic model of the wheel in question is derived in a meticulous manner. A continuously differentiable friction model is also considered in the modeling. By exploiting the inherent cascade interconnected structure of the wheel dynamics, an adaptive motion/force tracking controller is presented guaranteeing that the trajectory tracking errors asymptotically converge to zero while the contact force tracking errors can be made small enough by tuning design parameters. Simulation results are provided to validate the effectiveness of the proposed tracking methodology.
基金This work was supported by the National Key R&D Program of China“The study on Load-bearing and Moving Support Exoskeleton Robot Key Technology and Typical Application”(2017YFB1300502)This work is also supported by the National Natural Science Foundation of China“Research on gait detection and recognition technology of Parkinson’s disease based on all-fiber composite sensors”under Grant 61903280Hubei Key Laboratory of Digital Textile Equipment Open fund“Research on intelligent monitoring clothing based on micro-nano fiber composite sensor”under Grant DTL2019011.
文摘Purpose–The purpose of this paper is to apply a intelligent algorithm to conduct the force tracking control for electrohydraulic servo system(EHSS).Specifically,the adaptive neuro-fuzzy inference system(ANFIS)is selected to improve the control performance for EHSS.Design/methodology/approach–Two types of input–output data were chosen to train the ANFIS models.The inputs are the desired and actual forces,and the output is the current.The first type is to set a sinusoidal signal for the current to produce the actual driving force,and the desired force is chosen as same as the actual force.The other type is to give a sinusoidal signal for the desired force.Under the action of the PI controller,the actual force tracks the desired force,and the current is the output of the PI controller.Findings–The models built based on the two types of data are separately named as the ANFIS I controller and the ANFIS II controller.The results reveal that the ANFIS I controller possesses the best performance in terms of overshoot,rise time and mean absolute error and show adaptivity to different tracking conditions,including sinusoidal signal tracking and sudden change signal tracking.Originality/value–This paper is the first time to apply the ANFIS to optimize the force tracking control for EHSS.
基金Supported by the National Key Scientific Instrument and Equipment Development Projects of China under Grant No 81127901the National Natural Science Foundation of China under Grant Nos 61372017 and 30970828
文摘A modified Monte Carlo model of speckle tracking of shear wave propagation in scattering media is proposed. The established Monte Carlo model mainly concerns the variations of optical electric field and speckle. The two- dimensional intensity distribution and the time evolution of speckles in different probe locations are obtained. The fluctuation of speckle intensity tracks the acoustic-radiation-force shear wave propagation, and especially the reduction of speckle intensity implies attenuation of shear wave. Then, the shear wave velocity is estimated quantitatively on the basis of the time-to-peak algorithm and linear regression processing. The results reveal that a smaller sampling interval yields higher estimation precision and the shear wave velocity is estimated more efficiently by using speckle intensity difference than by using speckle contrast difference according to the estimation error. Hence, the shear wave velocity is estimated to be 2.25 m/s with relatively high accuracy for the estimation error reaches the minimum （0.071）.
基金the National Natural Science Foundation of China(Grant Nos.62103407,52075530,and 52175272)the State Key Laboratory of Robotics Foundation(Grant No.Y91Z0303)。
文摘Compliant interaction control is a key technology for robots performing contact-rich manipulation tasks.The design of the compliant controller needs to consider the robot hardware because complex control algorithms may not be compatible with the hardware performance,especially for some industrial robots with low bandwidth sensors.This paper focuses on effective and easy-to-use compliant control algorithms for position/velocity-controlled robots.Inspired by human arm stiffness adaptation behavior,a novel variable target stiffness(NVTS)admittance control strategy is proposed for adaptive force tracking,in which a proportional integral derivative(PID)variable stiffness law is designed to update the stiffness coefficient of the admittance function by the force and position feedback.Meanwhile,its stability and force-tracking capability are theoretically proven.In addition,an impact compensator(Impc)is integrated into the NVTS controller to enhance its disturbance-suppression capability when the robot is subjected to strong vibration disturbances in complicated surface polishing tasks.The proposed controllers are validated through four groups of experimental tests using different robots and the corresponding results demonstrate that they have high-accuracy tracking capability and strong adaptability in unknown environments.
文摘The control of single pneumatic muscle actuator is studied, as one basic partof research on the parallel-robot arthrosis actuated by pneumatic muscle actuators. Experimentsshow that a self-modified fuzzy-PID controller is obviously effective for its position servo and asimple PID controller is good for its force track.
基金supported by the National Key Research and Development Program of China (Grant No.2022YFB4702200)the National Natural Science Foundation of China (Grant Nos.52275020,62293514)。
文摘Stiffness adjustment is an important feature of human arm control.The adaptive variable impedance control can adapt to the robotic stiffness,but may result in a large overshoot.In this paper,nonlinear impedance control is proposed for collaborative robotic grinding,where nonlinear force feedback is designed to compensate for the nonlinear stiffness of the environment.Thus,the interaction system can be linearization to ensure the system stability.Moreover,a target trajectory adaptation strategy is studied to ensure the force tracking requirement.Then,switching law between trajectory tracking and force tracking is proposed when the robot performs a complex grinding task.The stability of the switch control as well as the trajectory adaptation law is proved.Experiments are conducted in a robotic grinding test rig,where the robot is used to grind a turbine blade.Experimental results show that the nonlinear impedance control can obtain stable grinding force,and have better grinding quality than the linear impedance control.
