This paper proposes a separated trajectory tracking controller for fishing ships at sea state level 6 to solve the trajectory tracking problem of a fishing ship in a 6-level sea state,and to adapt to different working...This paper proposes a separated trajectory tracking controller for fishing ships at sea state level 6 to solve the trajectory tracking problem of a fishing ship in a 6-level sea state,and to adapt to different working environments and safety requirements.The nonlinear feedback method is used to improve the closed-loop gain shaping algorithm.By introducing the sine function,the problem of excessive control energy of the system can be effectively solved.Moreover,an integral separation design is used to solve the influence of the integral term in conventional PID controllers on the transient performance of the system.In this paper,a common 32.98 m large fiberglass reinforced plastic(FRP)trawler is adopted for simulation research at the winds scale of Beaufort No.7.The results show that the track error is smaller than 3.5 m.The method is safe,feasible,concise and effective and has popularization value in the direction of fishing ship trajectory tracking control.This method can be used to improve the level of informatization and intelligence of fishing ships.展开更多
The trajectory tracking control performance of nonholonomic wheeled mobile robots(NWMRs)is subject to nonholonomic constraints,system uncertainties,and external disturbances.This paper proposes a barrier function-base...The trajectory tracking control performance of nonholonomic wheeled mobile robots(NWMRs)is subject to nonholonomic constraints,system uncertainties,and external disturbances.This paper proposes a barrier function-based adaptive sliding mode control(BFASMC)method to provide high-precision,fast-response performance and robustness for NWMRs.Compared with the conventional adaptive sliding mode control,the proposed control strategy can guarantee that the sliding mode variables converge to a predefined neighborhood of origin with a predefined reaching time independent of the prior knowledge of the uncertainties and disturbances bounds.Another advantage of the proposed algorithm is that the control gains can be adaptively adjusted to follow the disturbances amplitudes thanks to the barrier function.The benefit is that the overestimation of control gain can be eliminated,resulting in chattering reduction.Moreover,a modified barrier function-like control gain is employed to prevent the input saturation problem due to the physical limit of the actuator.The stability analysis and comparative experiments demonstrate that the proposed BFASMC can ensure the prespecified convergence performance of the NWMR system output variables and strong robustness against uncertainties/disturbances.展开更多
Spherical robot has good static and dynamic stability, which provides it with strong viability in hostile environment, but the lack of effective control methods has hindered its application and development. This artic...Spherical robot has good static and dynamic stability, which provides it with strong viability in hostile environment, but the lack of effective control methods has hindered its application and development. This article deals with the dynamic trajectory tracking problem of the spherical robot BHQ-2 designed for unmanned environment exploration. The dynamic model of the spherical robot is established with a simplified Boltzmann-Hamel equation, based on which a trajectory tracking controller is designed by using the back-stepping method. The convergence of the controller is proved with the Lyapunov stability theory. Numerical simulations show that with the controller the robot can globally and asymptotically track desired trajectories, both linear and circular.展开更多
In recent years,an innovative underactuated robot was developed,named as underactuated cable-driven trusslike manipulator(UCTM),to be suitable in aerospace applications.However,there has been strong consensus that the...In recent years,an innovative underactuated robot was developed,named as underactuated cable-driven trusslike manipulator(UCTM),to be suitable in aerospace applications.However,there has been strong consensus that the stabilization of planar underactuated manipulators without gravity is a great challenge since the system includes a second order nonholonomic constraint and most classical control methods are not suitable for this kind of system.Furthermore,the complexity of the truss-like structure results in tremendous difficulty of computational complicacy and high nonlinearity during dynamic modelling in addition to controller design.It is paramount to solve these difficulties for UCTM's future applications.To solve the above difficulties,this paper presents a dynamic modelling method for UCTM and a trajectory tracking control method based on partial feedback linearization(PFL)that fulfills the control goal of moving UCTM from its original position to a desired position by tracking a given trajectory of the joint angles.To achieve this,a model equivalent method is proposed to make UCTM equivalent with a three-link manipulator in the sense of dynamic behavior.Then the Lagrangian equation combined with complex vector method is proposed in the dynamic modelling process of UCTM,which simplifies the derivation procedure.Based on the established dynamic model,a coordinate transformation method is proposed to transform the control force matrix into the conventional form of an underactuated system,so that the control force can be separated from the unactuated term.The PFL method in combination with the LQR control method is then proposed to realize the targets that the joint angles can track given desired trajectory.Simulation experiments are conducted to verify the correctness and effectiveness of the proposed methods.展开更多
The natural frequency of the electrohydraulic system in mobile machinery is always very low,which brings difficulties to the controller design.To improve the tracking performance of the hydraulic system,mathematical m...The natural frequency of the electrohydraulic system in mobile machinery is always very low,which brings difficulties to the controller design.To improve the tracking performance of the hydraulic system,mathematical modeling of the electrohydraulic lifting system and the rubber hose was accomplished according to an electrohydraulic lifting test rig built in the laboratory.Then,valve compensation strategy,including spool opening compensation (SOC) and dead zone compensation (DZC),was designed based on the flow-pressure characteristic of a closed-centered proportional valve.Comparative experiments on point-to-point trajectory tracking between a proportional controller with the proposed compensations and a traditional PI controller were conducted.Experiment results show that the maximal absolute values of the tracking error are reduced from 0.039 m to 0.019 m for the slow point-to-point motion trajectory and from 0.085 m to 0.054 m for the fast point-to-point motion trajectory with the proposed compensations.Moreover,tracking error of the proposed controller was analyzed and corresponding suggestions to reduce the tracking error were put forward.展开更多
This paper addresses a three-dimensional(3D)trajectory tracking problem of underactuated autonomous underwater vehicles(AUVs)subjected to input saturation and external disturbances.The proposed controller can achieve ...This paper addresses a three-dimensional(3D)trajectory tracking problem of underactuated autonomous underwater vehicles(AUVs)subjected to input saturation and external disturbances.The proposed controller can achieve practical convergence of tracking errors for general reference trajectories,including persistently exciting(PE)time varying trajectories and fixed points.At first,a modified error state formulation is introduced to tackle the situation that desired velocities do not satisfy PE condition.Then,on the basis of the backstepping technique and a Nussbaum-type even function,a saturated controller is designed so that the tracking errors can converge to a bounded neighborhood of the origin.The stability analysis based on Lyapunov theory shows that the tracking errors are globally ultimately uniformly bounded.Finally,some simulation results illustrate the effectiveness and robustness of the proposed control strategy.展开更多
The nonplanar hex-rotor unmanned aerial vehicle(UAV)has much higher driving property,greater payload capacity and damage tolerance than quad-rotor UAV.It is difficult to design a highperformance controller of easy eng...The nonplanar hex-rotor unmanned aerial vehicle(UAV)has much higher driving property,greater payload capacity and damage tolerance than quad-rotor UAV.It is difficult to design a highperformance controller of easy engineering implementation for strongly coupled nonlinear hex-rotorUAV system.In response to this practical problem,an adaptive trajectory tracking control based oncharacteristic model for nonplanar hex-rotor is studied.Firstly,the dynamic model for the hex-rotorUAV is devised.Secondly,according to dynamic characteristics,environmental characteristics andcontrol performance requirements,the characteristic model of the hex-rotor UAV is constructed.Then,based on the characteristic model,a golden section adaptive controller is designed to realizetrajectory tracking.Furthermore,the stability analysis of the closed loop hex-rotor system is given.Finally,the validity of the proposed trajectory tracking control method adopted in the nonplanar hex-rotor UAV is demonstrated via numerical simulations and hex-rotor prototype experiments.展开更多
The trajectory tracking control for a 6-DOF robot manipulator with multiple inputs and outputs,non-linearity and strong coupling is studied.Firstly,a dynamical model for the 6-DOF robot manipulator is designed.From th...The trajectory tracking control for a 6-DOF robot manipulator with multiple inputs and outputs,non-linearity and strong coupling is studied.Firstly,a dynamical model for the 6-DOF robot manipulator is designed.From the view point of practical engineering,considering the model uncertainties and external disturbances,the robot manipulator is divided into 6 independent joint subsystems,and a linear active disturbance rejection controller(LADRC)is developed to track trajectory for each subsystem respectively.LADRC has few parameters that are easy to be adjusted in engineering.Linear expansion state observer(LESO)as the uncertainty observer is able to estimate the general uncertainties effectively.Eventually,the validity and robustness of the proposed method adopted in 6-DOF robot manipulator are demonstrated via numerical simulations and 6-DOF robot manipulator experiments,which is of practical value in engineering application.展开更多
Small bodies have the characteristics of noncooperative,irregular gravity,and complex terrain on the surface,which cause difficulties in successful landing for conventional landers.In this paper,a multinode flexible l...Small bodies have the characteristics of noncooperative,irregular gravity,and complex terrain on the surface,which cause difficulties in successful landing for conventional landers.In this paper,a multinode flexible lander is put forward to address the problem.The dynamics of this new lander are constructed based on the port-Hamilton framework.The trajectory-tracking formation controller for the lander is designed in a passive way.The proposed dynamics and controller are further validated through numerical simulations.This research presents a fresh concept that holds inspiration for future design involving small-body landers.展开更多
This paper proposes a scheme of trajectory tracking control for the hovercraft.Since the model of the hovercraft is under-actuated,nonlinear,and strongly coupled,it is a great challenge for the controller design.To so...This paper proposes a scheme of trajectory tracking control for the hovercraft.Since the model of the hovercraft is under-actuated,nonlinear,and strongly coupled,it is a great challenge for the controller design.To solve this problem,the control scheme is divided into two parts.Firstly,we employ differential flatness method to find a set of flat outputs and consider part of the nonlinear terms as uncertainties.Consequently,we convert the under-actuated system into a full-actuated one.Secondly,a reinforcement learning-based active disturbance rejection controller(RL-ADRC)is designed.In this method,an extended state observer(ESO)is designed to estimate the uncertainties of the system,and an actorcritic-based reinforcement learning(RL)algorithm is used to approximate the optimal control strategy.Based on the output of the ESO,the RL-ADRC compensates for the total uncertainties in real-time,and simultaneously,generates the optimal control strategy by RL algorithm.Simulation results show that,compared with the traditional ADRC method,RL-ADRC does not need to manually tune the controller parameters,and the control strategy is more robust.展开更多
This work studies the trajectory tracking control for unmanned aerial helicopter(UAH)system under both matched disturbance and mismatched ones.Initially,to tackle the strong coupling,an input-output feedback lineariza...This work studies the trajectory tracking control for unmanned aerial helicopter(UAH)system under both matched disturbance and mismatched ones.Initially,to tackle the strong coupling,an input-output feedback linearization method is utilized to simplify the nonlinear UAH system.Secondly,a set of finite-time disturbance observers(FTDOs)are proposed to estimate mismatched disturbances with their successive derivatives,which are utilized to design the feedforward controller via backstepping.Thirdly,as for matched disturbance,by defining the disturbance characterization index(DCI)to determine whether the disturbance is harmful or not for the UAH system,a feedback controller is proposed and a sufficient condition is established to ensure the convergence of the tracking error.Finally,some numerical simulations and comparisons illustrate the validity and advantages of our control scheme.展开更多
We present an iterative linear quadratic regulator(ILQR) method for trajectory tracking control of a wheeled mobile robot system.The proposed scheme involves a kinematic model linearization technique,a global trajecto...We present an iterative linear quadratic regulator(ILQR) method for trajectory tracking control of a wheeled mobile robot system.The proposed scheme involves a kinematic model linearization technique,a global trajectory generation algorithm,and trajectory tracking controller design.A lattice planner,which searches over a 3D(x,y,θ) configuration space,is adopted to generate the global trajectory.The ILQR method is used to design a local trajectory tracking controller.The effectiveness of the proposed method is demonstrated in simulation and experiment with a significantly asymmetric differential drive robot.The performance of the local controller is analyzed and compared with that of the existing linear quadratic regulator(LQR) method.According to the experiments,the new controller improves the control sequences(v,ω) iteratively and produces slightly better results.Specifically,two trajectories,'S' and '8' courses,are followed with sufficient accuracy using the proposed controller.展开更多
Purpose–Transcranial magnetic stimulation(TMS)is a non-invasive brain stimulation technique.Based on the unique functions of TMS,it has been widely used in clinical,scientific research and other fields.Nowadays,the r...Purpose–Transcranial magnetic stimulation(TMS)is a non-invasive brain stimulation technique.Based on the unique functions of TMS,it has been widely used in clinical,scientific research and other fields.Nowadays,the robot-assisted automatic TMS has become the trend.In order to simplify the operation procedures of robotic TMS and reduce the costs,the purpose of this paper is to apply the marker-based augmented-reality technology to robotic TMS system.Design/methodology/approach–By using the marker of ARToolKitPlus library and monocular camera,the patient’s head is positioned in real time.Furthermore,the force control is applied to keep contact between the coil and subject’s head.Findings–The authors fuse with visual positioning which is based on augmented-reality and force-control technologies to track the movements of the patient’s head,bring the coil closer to the stimulation site and increase treatment effects.Experimental results indicate that the trajectory tracking control of robotic TMS system designed in this paper is practical and flexible.Originality/value–This paper provides a trajectory tracking control method for the robotic TMS.The marker-based augmented-reality technology is implemented which simplifies the operation procedures of robotic TMS as well as reduce the costs.During the treatment process,the patients would wear an AR glasses,which can help patients relax through virtual scenes and reduce the uncomfortableness produce by treatment.展开更多
A distributionally robust model predictive control(DRMPC)scheme is proposed based on neural network(NN)modeling to achieve the trajectory tracking control of robot manipulators with state and control torque constraint...A distributionally robust model predictive control(DRMPC)scheme is proposed based on neural network(NN)modeling to achieve the trajectory tracking control of robot manipulators with state and control torque constraints.First,an NN is used to fit the motion data of robot manipulators for data-driven dynamic modeling,converting it into a linear prediction model through gradients.Then,by statistically analyzing the stochastic characteristics of the NN modeling errors,a distributionally robust model predictive controller is designed based on the chance constraints,and the optimization problem is transformed into a tractable quadratic programming(QP)problem under the distributionally robust optimization(DRO)framework.The recursive feasibility and convergence of the proposed algorithm are proven.Finally,the effectiveness of the proposed algorithm is verified through numerical simulation.展开更多
Space robot is assembled and tested in gravity environment, and completes on-orbit service（OOS） in microgravity environment. The kinematic and dynamic characteristic of the robot will change with the variations of g...Space robot is assembled and tested in gravity environment, and completes on-orbit service（OOS） in microgravity environment. The kinematic and dynamic characteristic of the robot will change with the variations of gravity in different working condition. Fully considering the change of kinematic and dynamic models caused by the change of gravity environment, a fuzzy adaptive robust control（FARC） strategy which is adaptive to these model variations is put forward for trajectory tracking control of space robot. A fuzzy algorithm is employed to approximate the nonlinear uncertainties in the model, adaptive laws of the parameters are constructed, and the approximation error is compensated by using a robust control algorithm. The stability of the control system is guaranteed based on the Lyapunov theory and the trajectory tracking control simulation is performed. The simulation results are compared with the proportional plus derivative（PD） controller, and the effectiveness to achieve better trajectory tracking performance under different gravity environment without changing the control parameters and the advantage of the proposed controller are verified.展开更多
The harsh working environment of unmanned mining electric shovels(UMESs)and the considerable inertia changes during the excavation process in the front-end mechanism pose major challenges to excavation trajectory trac...The harsh working environment of unmanned mining electric shovels(UMESs)and the considerable inertia changes during the excavation process in the front-end mechanism pose major challenges to excavation trajectory tracking.In this study,an adaptive Hamilton-Jacobi inequality(HJI)-based robust control method for UMES excavation systems with uncertainty was proposed for trajectory tracking control in intelligent mining.First,the excavation system dynamic model was analyzed using the Lagrangian method,and an excavation resistance prediction model and a material quality prediction model were constructed.The optimal excavation trajectory was described.Then,the HJI theorem was used to design an adaptive controller based on the dynamic model of the UMES,and a generalized regression neural network was introduced to fit the interference term in the control object to ensure the convergence of the control system.Subsequently,a Lyapunov function was constructed to demonstrate the stability of the control system to ensure the reliability of the excavation system.Finally,the method proposed in this study was verified under two different working conditions involving a typical material surface and a real material surface.The numerical simulation results demonstrated that the planned position and velocity were effectively tracked in both working conditions.Furthermore,it maintains an improved tracking effect under different uncertain disturbances,thus verifying the feasibility and robustness of the control system designed in this study.展开更多
This paper deals with a flexible macro-micro manipulator system, which includes a long flexible manipulator and a relatively short rigid manipulator attached to the tip of the macro manipulator. A flexible macro manip...This paper deals with a flexible macro-micro manipulator system, which includes a long flexible manipulator and a relatively short rigid manipulator attached to the tip of the macro manipulator. A flexible macro manipulator possesses the advantages of wide operating range, high speed, and low energy consumption, but the disadvantage of a low tracking precision. The macro-micro manipulator system improves tracking performance by compensating for the endpoint tracking error while maintaining the advantages of the flexible macro manipulator. A trajectory planning scheme was built utilizing the task space division method. The division point is chosen to optimize the error compensation and energy consumption for the whole system. Then movements of the macro-micro manipulator can be determined using separate inverse kinematic models. Simulation results for a planar 4-DOF macro-micro manipulator system are presented to show the effectiveness of the control system.展开更多
In this paper,we propose a novel noncausal control framework to address the energy maximization problem of wave energy converters(WECs)subject to constraints.The energy maximization problem of WECs is a constrained op...In this paper,we propose a novel noncausal control framework to address the energy maximization problem of wave energy converters(WECs)subject to constraints.The energy maximization problem of WECs is a constrained optimal control problem.The proposed control framework converts this problem into a reference trajectory tracking problem through the Fourier pseudo-spectral method(FPSM)and utilizes the online tracking adaptive dynamic programming(OTADP)algorithm to realize real-time trajectory tracking for practical use in the ocean environment.Using the wave prediction technique,the optimal trajectory is generated online through a receding horizon(RH)implementation.A critic neural network(NN)is applied to approximate the optimal cost value function and calculate the error-tracking control by solving the associated Hamilton-Jacobi-Bellman(HJB)equation.The proposed WEC control framework improves computational efficiency and makes the online control feasible in practice.Simulation results show the effects of the receding horizon implementation of FPSM with different window lengths and window functions,while verifying the performances of tracking control and energy absorption of WECs in two different sea conditions.展开更多
In this article,a robot skills learning framework is developed,which considers both motion modeling and execution.In order to enable the robot to learn skills from demonstrations,a learning method called dynamic movem...In this article,a robot skills learning framework is developed,which considers both motion modeling and execution.In order to enable the robot to learn skills from demonstrations,a learning method called dynamic movement primitives(DMPs)is introduced to model motion.A staged teaching strategy is integrated into DMPs frameworks to enhance the generality such that the complicated tasks can be also performed for multi-joint manipulators.The DMP connection method is used to make an accurate and smooth transition in position and velocity space to connect complex motion sequences.In addition,motions are categorized into different goals and durations.It is worth mentioning that an adaptive neural networks(NNs)control method is proposed to achieve highly accurate trajectory tracking and to ensure the performance of action execution,which is beneficial to the improvement of reliability of the skills learning system.The experiment test on the Baxter robot verifies the effectiveness of the proposed method.展开更多
基金supported by Liaoning Provincial Department of Education 2023 Basic Research Projects for Universities and Colleges(Grant No.JYTQN2023131)Liaoning Provincial Science and Technology Program:Cooperative Control and Recognition of Unmanned Vessels for Fishing Vessel Operation Scenarios(Grant No.600024003)Liaoning Provincial Department of Education Scientific Research Funding Project(Grant No.LJKZ0726).
文摘This paper proposes a separated trajectory tracking controller for fishing ships at sea state level 6 to solve the trajectory tracking problem of a fishing ship in a 6-level sea state,and to adapt to different working environments and safety requirements.The nonlinear feedback method is used to improve the closed-loop gain shaping algorithm.By introducing the sine function,the problem of excessive control energy of the system can be effectively solved.Moreover,an integral separation design is used to solve the influence of the integral term in conventional PID controllers on the transient performance of the system.In this paper,a common 32.98 m large fiberglass reinforced plastic(FRP)trawler is adopted for simulation research at the winds scale of Beaufort No.7.The results show that the track error is smaller than 3.5 m.The method is safe,feasible,concise and effective and has popularization value in the direction of fishing ship trajectory tracking control.This method can be used to improve the level of informatization and intelligence of fishing ships.
基金the China Scholarship Council(202106690037)the Natural Science Foundation of Anhui Province(19080885QE194)。
文摘The trajectory tracking control performance of nonholonomic wheeled mobile robots(NWMRs)is subject to nonholonomic constraints,system uncertainties,and external disturbances.This paper proposes a barrier function-based adaptive sliding mode control(BFASMC)method to provide high-precision,fast-response performance and robustness for NWMRs.Compared with the conventional adaptive sliding mode control,the proposed control strategy can guarantee that the sliding mode variables converge to a predefined neighborhood of origin with a predefined reaching time independent of the prior knowledge of the uncertainties and disturbances bounds.Another advantage of the proposed algorithm is that the control gains can be adaptively adjusted to follow the disturbances amplitudes thanks to the barrier function.The benefit is that the overestimation of control gain can be eliminated,resulting in chattering reduction.Moreover,a modified barrier function-like control gain is employed to prevent the input saturation problem due to the physical limit of the actuator.The stability analysis and comparative experiments demonstrate that the proposed BFASMC can ensure the prespecified convergence performance of the NWMR system output variables and strong robustness against uncertainties/disturbances.
基金National Natural Science Foundation of China (50705003)National High Technology Research and Development Program of China (2007AA04Z252).
文摘Spherical robot has good static and dynamic stability, which provides it with strong viability in hostile environment, but the lack of effective control methods has hindered its application and development. This article deals with the dynamic trajectory tracking problem of the spherical robot BHQ-2 designed for unmanned environment exploration. The dynamic model of the spherical robot is established with a simplified Boltzmann-Hamel equation, based on which a trajectory tracking controller is designed by using the back-stepping method. The convergence of the controller is proved with the Lyapunov stability theory. Numerical simulations show that with the controller the robot can globally and asymptotically track desired trajectories, both linear and circular.
基金Projects(51275107,52005124)supported by the National Natural Science Foundation of China。
文摘In recent years,an innovative underactuated robot was developed,named as underactuated cable-driven trusslike manipulator(UCTM),to be suitable in aerospace applications.However,there has been strong consensus that the stabilization of planar underactuated manipulators without gravity is a great challenge since the system includes a second order nonholonomic constraint and most classical control methods are not suitable for this kind of system.Furthermore,the complexity of the truss-like structure results in tremendous difficulty of computational complicacy and high nonlinearity during dynamic modelling in addition to controller design.It is paramount to solve these difficulties for UCTM's future applications.To solve the above difficulties,this paper presents a dynamic modelling method for UCTM and a trajectory tracking control method based on partial feedback linearization(PFL)that fulfills the control goal of moving UCTM from its original position to a desired position by tracking a given trajectory of the joint angles.To achieve this,a model equivalent method is proposed to make UCTM equivalent with a three-link manipulator in the sense of dynamic behavior.Then the Lagrangian equation combined with complex vector method is proposed in the dynamic modelling process of UCTM,which simplifies the derivation procedure.Based on the established dynamic model,a coordinate transformation method is proposed to transform the control force matrix into the conventional form of an underactuated system,so that the control force can be separated from the unactuated term.The PFL method in combination with the LQR control method is then proposed to realize the targets that the joint angles can track given desired trajectory.Simulation experiments are conducted to verify the correctness and effectiveness of the proposed methods.
基金Project(2006CB705400)supported by the National Basic Research Program of China
文摘The natural frequency of the electrohydraulic system in mobile machinery is always very low,which brings difficulties to the controller design.To improve the tracking performance of the hydraulic system,mathematical modeling of the electrohydraulic lifting system and the rubber hose was accomplished according to an electrohydraulic lifting test rig built in the laboratory.Then,valve compensation strategy,including spool opening compensation (SOC) and dead zone compensation (DZC),was designed based on the flow-pressure characteristic of a closed-centered proportional valve.Comparative experiments on point-to-point trajectory tracking between a proportional controller with the proposed compensations and a traditional PI controller were conducted.Experiment results show that the maximal absolute values of the tracking error are reduced from 0.039 m to 0.019 m for the slow point-to-point motion trajectory and from 0.085 m to 0.054 m for the fast point-to-point motion trajectory with the proposed compensations.Moreover,tracking error of the proposed controller was analyzed and corresponding suggestions to reduce the tracking error were put forward.
基金the National Natural Science Founda-tion of China(No.51309133)。
文摘This paper addresses a three-dimensional(3D)trajectory tracking problem of underactuated autonomous underwater vehicles(AUVs)subjected to input saturation and external disturbances.The proposed controller can achieve practical convergence of tracking errors for general reference trajectories,including persistently exciting(PE)time varying trajectories and fixed points.At first,a modified error state formulation is introduced to tackle the situation that desired velocities do not satisfy PE condition.Then,on the basis of the backstepping technique and a Nussbaum-type even function,a saturated controller is designed so that the tracking errors can converge to a bounded neighborhood of the origin.The stability analysis based on Lyapunov theory shows that the tracking errors are globally ultimately uniformly bounded.Finally,some simulation results illustrate the effectiveness and robustness of the proposed control strategy.
基金Supported by the Science and Technology Development Plan Project of Jilin Province(No.20200201294JC)。
文摘The nonplanar hex-rotor unmanned aerial vehicle(UAV)has much higher driving property,greater payload capacity and damage tolerance than quad-rotor UAV.It is difficult to design a highperformance controller of easy engineering implementation for strongly coupled nonlinear hex-rotorUAV system.In response to this practical problem,an adaptive trajectory tracking control based oncharacteristic model for nonplanar hex-rotor is studied.Firstly,the dynamic model for the hex-rotorUAV is devised.Secondly,according to dynamic characteristics,environmental characteristics andcontrol performance requirements,the characteristic model of the hex-rotor UAV is constructed.Then,based on the characteristic model,a golden section adaptive controller is designed to realizetrajectory tracking.Furthermore,the stability analysis of the closed loop hex-rotor system is given.Finally,the validity of the proposed trajectory tracking control method adopted in the nonplanar hex-rotor UAV is demonstrated via numerical simulations and hex-rotor prototype experiments.
基金Supported by the National Natural Science Foundation of China(No.11672290)
文摘The trajectory tracking control for a 6-DOF robot manipulator with multiple inputs and outputs,non-linearity and strong coupling is studied.Firstly,a dynamical model for the 6-DOF robot manipulator is designed.From the view point of practical engineering,considering the model uncertainties and external disturbances,the robot manipulator is divided into 6 independent joint subsystems,and a linear active disturbance rejection controller(LADRC)is developed to track trajectory for each subsystem respectively.LADRC has few parameters that are easy to be adjusted in engineering.Linear expansion state observer(LESO)as the uncertainty observer is able to estimate the general uncertainties effectively.Eventually,the validity and robustness of the proposed method adopted in 6-DOF robot manipulator are demonstrated via numerical simulations and 6-DOF robot manipulator experiments,which is of practical value in engineering application.
基金supported by the National Key R&D Program(grant number 2019YFA0706500)the National Natural Science Foundation of China(grant number 62273118)National defense basic research projects(grant numbers JCKY2021603B030,JCKY2020903B002).
文摘Small bodies have the characteristics of noncooperative,irregular gravity,and complex terrain on the surface,which cause difficulties in successful landing for conventional landers.In this paper,a multinode flexible lander is put forward to address the problem.The dynamics of this new lander are constructed based on the port-Hamilton framework.The trajectory-tracking formation controller for the lander is designed in a passive way.The proposed dynamics and controller are further validated through numerical simulations.This research presents a fresh concept that holds inspiration for future design involving small-body landers.
基金This paper was supported by the National Natural Science Foundation of China under Grant No.61720106010.
文摘This paper proposes a scheme of trajectory tracking control for the hovercraft.Since the model of the hovercraft is under-actuated,nonlinear,and strongly coupled,it is a great challenge for the controller design.To solve this problem,the control scheme is divided into two parts.Firstly,we employ differential flatness method to find a set of flat outputs and consider part of the nonlinear terms as uncertainties.Consequently,we convert the under-actuated system into a full-actuated one.Secondly,a reinforcement learning-based active disturbance rejection controller(RL-ADRC)is designed.In this method,an extended state observer(ESO)is designed to estimate the uncertainties of the system,and an actorcritic-based reinforcement learning(RL)algorithm is used to approximate the optimal control strategy.Based on the output of the ESO,the RL-ADRC compensates for the total uncertainties in real-time,and simultaneously,generates the optimal control strategy by RL algorithm.Simulation results show that,compared with the traditional ADRC method,RL-ADRC does not need to manually tune the controller parameters,and the control strategy is more robust.
基金This work was supported by National Natural Science Foundations of China(Nos.62073164,61873127,61922042)the Foundation of Equipment Pre-research Project of Key Laboratory(No.61422200306).
文摘This work studies the trajectory tracking control for unmanned aerial helicopter(UAH)system under both matched disturbance and mismatched ones.Initially,to tackle the strong coupling,an input-output feedback linearization method is utilized to simplify the nonlinear UAH system.Secondly,a set of finite-time disturbance observers(FTDOs)are proposed to estimate mismatched disturbances with their successive derivatives,which are utilized to design the feedforward controller via backstepping.Thirdly,as for matched disturbance,by defining the disturbance characterization index(DCI)to determine whether the disturbance is harmful or not for the UAH system,a feedback controller is proposed and a sufficient condition is established to ensure the convergence of the tracking error.Finally,some numerical simulations and comparisons illustrate the validity and advantages of our control scheme.
基金Project (Nos. 90920304 and 91120015) supported by the National Natural Science Foundation of China
文摘We present an iterative linear quadratic regulator(ILQR) method for trajectory tracking control of a wheeled mobile robot system.The proposed scheme involves a kinematic model linearization technique,a global trajectory generation algorithm,and trajectory tracking controller design.A lattice planner,which searches over a 3D(x,y,θ) configuration space,is adopted to generate the global trajectory.The ILQR method is used to design a local trajectory tracking controller.The effectiveness of the proposed method is demonstrated in simulation and experiment with a significantly asymmetric differential drive robot.The performance of the local controller is analyzed and compared with that of the existing linear quadratic regulator(LQR) method.According to the experiments,the new controller improves the control sequences(v,ω) iteratively and produces slightly better results.Specifically,two trajectories,'S' and '8' courses,are followed with sufficient accuracy using the proposed controller.
文摘Purpose–Transcranial magnetic stimulation(TMS)is a non-invasive brain stimulation technique.Based on the unique functions of TMS,it has been widely used in clinical,scientific research and other fields.Nowadays,the robot-assisted automatic TMS has become the trend.In order to simplify the operation procedures of robotic TMS and reduce the costs,the purpose of this paper is to apply the marker-based augmented-reality technology to robotic TMS system.Design/methodology/approach–By using the marker of ARToolKitPlus library and monocular camera,the patient’s head is positioned in real time.Furthermore,the force control is applied to keep contact between the coil and subject’s head.Findings–The authors fuse with visual positioning which is based on augmented-reality and force-control technologies to track the movements of the patient’s head,bring the coil closer to the stimulation site and increase treatment effects.Experimental results indicate that the trajectory tracking control of robotic TMS system designed in this paper is practical and flexible.Originality/value–This paper provides a trajectory tracking control method for the robotic TMS.The marker-based augmented-reality technology is implemented which simplifies the operation procedures of robotic TMS as well as reduce the costs.During the treatment process,the patients would wear an AR glasses,which can help patients relax through virtual scenes and reduce the uncomfortableness produce by treatment.
基金Project supported by the National Natural Science Foundation of China(Nos.62273245 and 62173033)the Sichuan Science and Technology Program of China(No.2024NSFSC1486)the Opening Project of Robotic Satellite Key Laboratory of Sichuan Province of China。
文摘A distributionally robust model predictive control(DRMPC)scheme is proposed based on neural network(NN)modeling to achieve the trajectory tracking control of robot manipulators with state and control torque constraints.First,an NN is used to fit the motion data of robot manipulators for data-driven dynamic modeling,converting it into a linear prediction model through gradients.Then,by statistically analyzing the stochastic characteristics of the NN modeling errors,a distributionally robust model predictive controller is designed based on the chance constraints,and the optimization problem is transformed into a tractable quadratic programming(QP)problem under the distributionally robust optimization(DRO)framework.The recursive feasibility and convergence of the proposed algorithm are proven.Finally,the effectiveness of the proposed algorithm is verified through numerical simulation.
基金supported by the National High-tech Research and Development Program of China
文摘Space robot is assembled and tested in gravity environment, and completes on-orbit service（OOS） in microgravity environment. The kinematic and dynamic characteristic of the robot will change with the variations of gravity in different working condition. Fully considering the change of kinematic and dynamic models caused by the change of gravity environment, a fuzzy adaptive robust control（FARC） strategy which is adaptive to these model variations is put forward for trajectory tracking control of space robot. A fuzzy algorithm is employed to approximate the nonlinear uncertainties in the model, adaptive laws of the parameters are constructed, and the approximation error is compensated by using a robust control algorithm. The stability of the control system is guaranteed based on the Lyapunov theory and the trajectory tracking control simulation is performed. The simulation results are compared with the proportional plus derivative（PD） controller, and the effectiveness to achieve better trajectory tracking performance under different gravity environment without changing the control parameters and the advantage of the proposed controller are verified.
基金supported by the Major Science and Technology Project of Shanxi Province,China(Grant No.20191101014)the National Natural Science Foundation of China(Grant No.52075068).
文摘The harsh working environment of unmanned mining electric shovels(UMESs)and the considerable inertia changes during the excavation process in the front-end mechanism pose major challenges to excavation trajectory tracking.In this study,an adaptive Hamilton-Jacobi inequality(HJI)-based robust control method for UMES excavation systems with uncertainty was proposed for trajectory tracking control in intelligent mining.First,the excavation system dynamic model was analyzed using the Lagrangian method,and an excavation resistance prediction model and a material quality prediction model were constructed.The optimal excavation trajectory was described.Then,the HJI theorem was used to design an adaptive controller based on the dynamic model of the UMES,and a generalized regression neural network was introduced to fit the interference term in the control object to ensure the convergence of the control system.Subsequently,a Lyapunov function was constructed to demonstrate the stability of the control system to ensure the reliability of the excavation system.Finally,the method proposed in this study was verified under two different working conditions involving a typical material surface and a real material surface.The numerical simulation results demonstrated that the planned position and velocity were effectively tracked in both working conditions.Furthermore,it maintains an improved tracking effect under different uncertain disturbances,thus verifying the feasibility and robustness of the control system designed in this study.
基金the National Natural Science Foundation of China (No. 60305008)
文摘This paper deals with a flexible macro-micro manipulator system, which includes a long flexible manipulator and a relatively short rigid manipulator attached to the tip of the macro manipulator. A flexible macro manipulator possesses the advantages of wide operating range, high speed, and low energy consumption, but the disadvantage of a low tracking precision. The macro-micro manipulator system improves tracking performance by compensating for the endpoint tracking error while maintaining the advantages of the flexible macro manipulator. A trajectory planning scheme was built utilizing the task space division method. The division point is chosen to optimize the error compensation and energy consumption for the whole system. Then movements of the macro-micro manipulator can be determined using separate inverse kinematic models. Simulation results for a planar 4-DOF macro-micro manipulator system are presented to show the effectiveness of the control system.
基金supported by the Key R&D Program of Shandong Province,China(No.2021ZLGX04)the Taishan Industrial Experts Programme(No.tsls20231203)。
文摘In this paper,we propose a novel noncausal control framework to address the energy maximization problem of wave energy converters(WECs)subject to constraints.The energy maximization problem of WECs is a constrained optimal control problem.The proposed control framework converts this problem into a reference trajectory tracking problem through the Fourier pseudo-spectral method(FPSM)and utilizes the online tracking adaptive dynamic programming(OTADP)algorithm to realize real-time trajectory tracking for practical use in the ocean environment.Using the wave prediction technique,the optimal trajectory is generated online through a receding horizon(RH)implementation.A critic neural network(NN)is applied to approximate the optimal cost value function and calculate the error-tracking control by solving the associated Hamilton-Jacobi-Bellman(HJB)equation.The proposed WEC control framework improves computational efficiency and makes the online control feasible in practice.Simulation results show the effects of the receding horizon implementation of FPSM with different window lengths and window functions,while verifying the performances of tracking control and energy absorption of WECs in two different sea conditions.
基金National Natural Science Foundation of China(Nos.62225304,92148204 and 62061160371)National Key Research and Development Program of China(Nos.2021ZD0114503 and 2019YFB1703600)Beijing Top Discipline for Artificial Intelligence Science and Engineering,University of Science and Technology Beijing,and the Beijing Natural Science Foundation(No.JQ20026).
文摘In this article,a robot skills learning framework is developed,which considers both motion modeling and execution.In order to enable the robot to learn skills from demonstrations,a learning method called dynamic movement primitives(DMPs)is introduced to model motion.A staged teaching strategy is integrated into DMPs frameworks to enhance the generality such that the complicated tasks can be also performed for multi-joint manipulators.The DMP connection method is used to make an accurate and smooth transition in position and velocity space to connect complex motion sequences.In addition,motions are categorized into different goals and durations.It is worth mentioning that an adaptive neural networks(NNs)control method is proposed to achieve highly accurate trajectory tracking and to ensure the performance of action execution,which is beneficial to the improvement of reliability of the skills learning system.The experiment test on the Baxter robot verifies the effectiveness of the proposed method.
