Dear Editor,This letter considers the problem of achieving optimal formation control in multiple vertical take-off and landing(VTOL)unmanned aerial vehicles(UAVs).Specifically,the objective is to derive the vehicles t...Dear Editor,This letter considers the problem of achieving optimal formation control in multiple vertical take-off and landing(VTOL)unmanned aerial vehicles(UAVs).Specifically,the objective is to derive the vehicles to the desired formation shape while minimizing the total cost function.Leveraging the backstepping design,a distributed control strategy is proposed that incorporates a dynamic system for generating a reference trajectory and a trajectory tracking controller for each vehicle.展开更多
Inspired by large and medium-sized birds,two kinds of flapping-wing flying robots with wingspans beyond 2 meters were developed.They have the appearance of a hawk and a phoenix respectively,so they are called HIT-Hawk...Inspired by large and medium-sized birds,two kinds of flapping-wing flying robots with wingspans beyond 2 meters were developed.They have the appearance of a hawk and a phoenix respectively,so they are called HIT-Hawk and HIT-Phoenix.In this paper,the bionic concept,theoretical analysis,design and manufacturing are introduced in detail.Firstly,the flight principle and characteristics of large and medium-sized birds were summarized.Then,the aerodynamics was modeled based on the thin airfoil theory,and the main design basis was established.Secondly,the mechanical structures of HIT-Hawk and HIT-Phoenix were designed to ensure the lateral and longitudinal stability and have optimized flight performance.Moreover,an autonomous flight control method was proposed and realized in highly integrated on-onboard controller;it satisfies the strict restrictions on mass,size,power and shape.Finally,the prototypes were fabricated and verified through practical flight experiments.The wingspans of these two flapping wing aircrafts are 2.0 m and 2.3 m respectively,the take-off weights are 1.15 kg and 0.86 kg,and the maximum stable endurance is 65 min(with battery of 3S LiPo,4300 mAh)and 8 min(with battery of 3S LiPo,800 mAh).Their wind resistance can both reach level 4.Compared with the small and micro flapping-wing aerial vehicles that mimic insects or small birds,they both have strong load capacity,strong wind resistance and long endurance.展开更多
With advances in modern agricultural parks,the rural energy structure has undergone profound change,leading to the emergence of an agricultural energy internet.This integrated system combines agricultural energy utili...With advances in modern agricultural parks,the rural energy structure has undergone profound change,leading to the emergence of an agricultural energy internet.This integrated system combines agricultural energy utilization,the information internet,and agricultural production.Accordingly,this study proposes a regulation flexibility assessment approach and optimal aggregation strategy of greenhouse loads(GHLs)for modern agricultural parks.First,taking into account the operational characteristics of typical GHLs,refined load demand models for lighting,humidification,and temperature-controlled loads are established.Secondly,the recursive least squares method-based parameter identification method is designed to accurately determine key GHL model parameters.Finally,based on the regulation flexibility of quantitatively evaluated GHLs,GHLs are optimally aggregated into multiple flexible aggregators considering minimal operational cost and greenhouse environmental constraints.The results indicate that the proposed regulation flexibility assessment approach and optimal aggregation strategy of GHLs can alleviate the peak regulation pressure on power grids by flexibly shifting the load demands of GHLs.展开更多
With the increase of the renewable energy generator capacity,the requirements of the power system for grid-connected converters are evolving,which leads to diverse control schemes and increased complexity of systemati...With the increase of the renewable energy generator capacity,the requirements of the power system for grid-connected converters are evolving,which leads to diverse control schemes and increased complexity of systematic stability analysis.Although various frequency-domain models are developed to identify oscillation causes,the discrepancies between them are rarely studied.This study aims to clarify these discrepancies and provide circuit insights for stability analysis by using different frequency-domain models.This study emphasizes the limitations of assuming that the transfer function of the self-stable converter does not have right half-plane(RHP)poles.To ensure that the self-stable converters are represented by a frequency-domain model without RHP poles,the applicability of this model of grid-following(GFL)and grid-forming(GFM)converters is discussed.This study recommends that the GFM converters with ideal sources should be represented in parallel with the P/Q-θ/V admittance model rather than the V-I impedance model.Two cases are conducted to illustrate the rationality of the P/Q-θ/V admittance model.Additionally,a hybrid frequency-domain modeling framework and stability criteria are proposed for the power system with several GFL and GFM converters.The stability criteria eliminates the need to check the RHP pole numbers in the non-passive subsystem when applying the Nyquist stability criterion,thereby reducing the complexity of stability analysis.Simulations are carried out to validate the correctness of the frequency-domain model and the stability criteria.展开更多
In order to meet the requirements of the space environment for the lightweight and load capacity of the manipulator,this paper designs a lightweight space manipulator with a weight of 9.23 kg and a load of 2 kg.It ado...In order to meet the requirements of the space environment for the lightweight and load capacity of the manipulator,this paper designs a lightweight space manipulator with a weight of 9.23 kg and a load of 2 kg.It adopts the EtherCAT communication protocol and has the characteristics of high load-to-weight ratio.In order to achieve constant force tracking under the condition of unknown environmental parameters,an integral adaptive admittance control method is proposed.The control law is expressed as a third-order linear system equation,the operating environment is equivalent to a spring model,and the control error transfer function is derived.The control performance under the step response is further analyzed.The simulation results show that the proposed integral adaptive admittance control method has better performance than the traditional method.It has no steady-state error,overcomes the problems caused by nonlinear discrete compensation,and can facilitate analysis in the frequency domain,realize parameter optimization,and improve calculation accuracy.展开更多
Most existing biped robots can only walk with their feet or move by wheels.To combine the best of both worlds,this paper introduces the dynamic wheeled control including wheeled locomotion and in-situ wheel-to-foot(Wt...Most existing biped robots can only walk with their feet or move by wheels.To combine the best of both worlds,this paper introduces the dynamic wheeled control including wheeled locomotion and in-situ wheel-to-foot(WtF)transformation of a full-sized wheel-biped transformable robot SR600-II.It can traverse on flat surfaces by wheels and transform to footed stance through its switching modules when facing obstacles.For wheeled locomotion,the kinematics considering upper-body lumped center-of-mass(CoM)constraint is first derived.Then,the dynamics of wheeled locomotion is modeled as a wheeled inverted pendulum(WIP)with variables related to the pose of upper body.After that,a parameter-varying linear quadratic regulator(LQR)controller is utilized to enable dynamic wheeled locomotion.For WtF transformation,the WtF balance constraints are first revealed.Then,a WtF transformation strategy is proposed to tackle the problem when robot transforms from wheeled balance state to in-situ biped stance state.It enables the robot to pass by the transition stages in which both wheels and feet touch the ground and to maintain its balance at the same time.Simulations and experiments on the SR600-II prototype have validated the efficacy of proposed dynamic wheeled control strategies for both wheeled locomotion and in-situ WtF transformation.展开更多
Salient object detection(SOD)has garnered significant interest because of its pivotal role in numerous computer vision and graphics applications.Deep convolutional neural networks have been widely applied in salient o...Salient object detection(SOD)has garnered significant interest because of its pivotal role in numerous computer vision and graphics applications.Deep convolutional neural networks have been widely applied in salient object detection and have achieved remarkable results in this field.To enhance the network representation ability,a very important means is to increase the depth of the neural network to learn as many hierarchical features as possible.However,the information related to the input image features will be lost with the increase in network depth,and existing models suffer from information distortion caused by interpolation during up-sampling and downsampling.In response to this drawback,this article focuses on the feature level and label level to address this significant challenge.On the one hand,a novel cascaded interaction network with a guidance module named global-local aligned attention(GAA)is designed to reduce the negative impact of interpolation on the feature side.On the other hand,a deep supervision strategy based on edge erosion is proposed to reduce the negative guidance of label interpolation on lateral output.Extensive experiments on five popular datasets demonstrate the superiority of our method.展开更多
基金supported by the National Natural Science Foundation of China(62003214)Guangdong Basic and Applied Basic Research Foundation(2024A1515012681)+1 种基金the Natural Science Foundation of Shanghai(22ZR1443600)Shanghai Pujiang Programme(23PJD064).
文摘Dear Editor,This letter considers the problem of achieving optimal formation control in multiple vertical take-off and landing(VTOL)unmanned aerial vehicles(UAVs).Specifically,the objective is to derive the vehicles to the desired formation shape while minimizing the total cost function.Leveraging the backstepping design,a distributed control strategy is proposed that incorporates a dynamic system for generating a reference trajectory and a trajectory tracking controller for each vehicle.
基金supported by the National Natural Science Founda-tion of China(Grant No.U1613227)Guangdong Special Support Pro-gram,China(GrantNo.2017TX04X0071)the Basic Research Pro-gram of Shenzhen,China(JCYJ20180507183610564,JCYJ20190806144416980).
文摘Inspired by large and medium-sized birds,two kinds of flapping-wing flying robots with wingspans beyond 2 meters were developed.They have the appearance of a hawk and a phoenix respectively,so they are called HIT-Hawk and HIT-Phoenix.In this paper,the bionic concept,theoretical analysis,design and manufacturing are introduced in detail.Firstly,the flight principle and characteristics of large and medium-sized birds were summarized.Then,the aerodynamics was modeled based on the thin airfoil theory,and the main design basis was established.Secondly,the mechanical structures of HIT-Hawk and HIT-Phoenix were designed to ensure the lateral and longitudinal stability and have optimized flight performance.Moreover,an autonomous flight control method was proposed and realized in highly integrated on-onboard controller;it satisfies the strict restrictions on mass,size,power and shape.Finally,the prototypes were fabricated and verified through practical flight experiments.The wingspans of these two flapping wing aircrafts are 2.0 m and 2.3 m respectively,the take-off weights are 1.15 kg and 0.86 kg,and the maximum stable endurance is 65 min(with battery of 3S LiPo,4300 mAh)and 8 min(with battery of 3S LiPo,800 mAh).Their wind resistance can both reach level 4.Compared with the small and micro flapping-wing aerial vehicles that mimic insects or small birds,they both have strong load capacity,strong wind resistance and long endurance.
基金the Science and Technology Project of State Grid Corporation of China(No.1400-202224249A-1-1-ZN)the National Natural Science Foundation of China(No.52077075 and No.72271068)+2 种基金the Foundations of Shenzhen and Technology Committee(No.GJHZ20210705141811036 and No.GXWD20220811151845006)the Major Science and Technology Special Projects in Xinjiang Autonomous Region(No.2022A01007)the Fundamental Research Funds for the Central Universities(No.2023JC001).
文摘With advances in modern agricultural parks,the rural energy structure has undergone profound change,leading to the emergence of an agricultural energy internet.This integrated system combines agricultural energy utilization,the information internet,and agricultural production.Accordingly,this study proposes a regulation flexibility assessment approach and optimal aggregation strategy of greenhouse loads(GHLs)for modern agricultural parks.First,taking into account the operational characteristics of typical GHLs,refined load demand models for lighting,humidification,and temperature-controlled loads are established.Secondly,the recursive least squares method-based parameter identification method is designed to accurately determine key GHL model parameters.Finally,based on the regulation flexibility of quantitatively evaluated GHLs,GHLs are optimally aggregated into multiple flexible aggregators considering minimal operational cost and greenhouse environmental constraints.The results indicate that the proposed regulation flexibility assessment approach and optimal aggregation strategy of GHLs can alleviate the peak regulation pressure on power grids by flexibly shifting the load demands of GHLs.
基金supported by Guangdong Basic and Applied Basic Research Foundation(No.2022A1515240030)Shenzhen Innovation&Entrepreneurship Program(No.JSGG20211029095544001)。
文摘With the increase of the renewable energy generator capacity,the requirements of the power system for grid-connected converters are evolving,which leads to diverse control schemes and increased complexity of systematic stability analysis.Although various frequency-domain models are developed to identify oscillation causes,the discrepancies between them are rarely studied.This study aims to clarify these discrepancies and provide circuit insights for stability analysis by using different frequency-domain models.This study emphasizes the limitations of assuming that the transfer function of the self-stable converter does not have right half-plane(RHP)poles.To ensure that the self-stable converters are represented by a frequency-domain model without RHP poles,the applicability of this model of grid-following(GFL)and grid-forming(GFM)converters is discussed.This study recommends that the GFM converters with ideal sources should be represented in parallel with the P/Q-θ/V admittance model rather than the V-I impedance model.Two cases are conducted to illustrate the rationality of the P/Q-θ/V admittance model.Additionally,a hybrid frequency-domain modeling framework and stability criteria are proposed for the power system with several GFL and GFM converters.The stability criteria eliminates the need to check the RHP pole numbers in the non-passive subsystem when applying the Nyquist stability criterion,thereby reducing the complexity of stability analysis.Simulations are carried out to validate the correctness of the frequency-domain model and the stability criteria.
基金This work was supported by the Key Research and Development Program of Guangdong Province(2019B090915001)the Basic Research Program of Shenzhen(JSGG20200103103401723,JCYJ20190806142818365,and JCYJ20180507183610564).
文摘In order to meet the requirements of the space environment for the lightweight and load capacity of the manipulator,this paper designs a lightweight space manipulator with a weight of 9.23 kg and a load of 2 kg.It adopts the EtherCAT communication protocol and has the characteristics of high load-to-weight ratio.In order to achieve constant force tracking under the condition of unknown environmental parameters,an integral adaptive admittance control method is proposed.The control law is expressed as a third-order linear system equation,the operating environment is equivalent to a spring model,and the control error transfer function is derived.The control performance under the step response is further analyzed.The simulation results show that the proposed integral adaptive admittance control method has better performance than the traditional method.It has no steady-state error,overcomes the problems caused by nonlinear discrete compensation,and can facilitate analysis in the frequency domain,realize parameter optimization,and improve calculation accuracy.
文摘Most existing biped robots can only walk with their feet or move by wheels.To combine the best of both worlds,this paper introduces the dynamic wheeled control including wheeled locomotion and in-situ wheel-to-foot(WtF)transformation of a full-sized wheel-biped transformable robot SR600-II.It can traverse on flat surfaces by wheels and transform to footed stance through its switching modules when facing obstacles.For wheeled locomotion,the kinematics considering upper-body lumped center-of-mass(CoM)constraint is first derived.Then,the dynamics of wheeled locomotion is modeled as a wheeled inverted pendulum(WIP)with variables related to the pose of upper body.After that,a parameter-varying linear quadratic regulator(LQR)controller is utilized to enable dynamic wheeled locomotion.For WtF transformation,the WtF balance constraints are first revealed.Then,a WtF transformation strategy is proposed to tackle the problem when robot transforms from wheeled balance state to in-situ biped stance state.It enables the robot to pass by the transition stages in which both wheels and feet touch the ground and to maintain its balance at the same time.Simulations and experiments on the SR600-II prototype have validated the efficacy of proposed dynamic wheeled control strategies for both wheeled locomotion and in-situ WtF transformation.
基金supported in part by Shenzhen Science and Technology Program,China(No.GXWD20231129140908002).
文摘Salient object detection(SOD)has garnered significant interest because of its pivotal role in numerous computer vision and graphics applications.Deep convolutional neural networks have been widely applied in salient object detection and have achieved remarkable results in this field.To enhance the network representation ability,a very important means is to increase the depth of the neural network to learn as many hierarchical features as possible.However,the information related to the input image features will be lost with the increase in network depth,and existing models suffer from information distortion caused by interpolation during up-sampling and downsampling.In response to this drawback,this article focuses on the feature level and label level to address this significant challenge.On the one hand,a novel cascaded interaction network with a guidance module named global-local aligned attention(GAA)is designed to reduce the negative impact of interpolation on the feature side.On the other hand,a deep supervision strategy based on edge erosion is proposed to reduce the negative guidance of label interpolation on lateral output.Extensive experiments on five popular datasets demonstrate the superiority of our method.
