In order to obtain a simple way for the force analysis of metamorphic mechanisms, the systematic method to unify the force analysis approach of metamorphic mechanisms as that of conventional planar mechanisms is propo...In order to obtain a simple way for the force analysis of metamorphic mechanisms, the systematic method to unify the force analysis approach of metamorphic mechanisms as that of conventional planar mechanisms is proposed. A force analysis method of metamorphic mechanisms is developed by transforming the augmented Assur groups into Assur groups, so that the force analysis problem of metamorphic mechanisms is converted into the force analysis problems of conventional planar mechanisms. The constraint force change rules and values of metamorphic joints are obtained by the proposed method, and the constraint force analysis equations of revolute metamorphic joints in augmented Assur group RRRR and prismatic metamorphic joints in augmented Assur group RRPR are deduced. The constraint force analysis is illustrated by the constrained spring force design of paper folding metamorphic mechanism, and its metamorphic working process is controlled by the spring force and geometric constraints of metamorphic joints. The results of spring force show that developped design method and approach are feasible and practical. By transforming augmented Assur groups into Assur groups, a new method for the constraint force analysis of metamorphic joints is proposed firstly to provide the basis for dynamic analysis of metamorphic mechanism.展开更多
The purpose of this paper is to present an extended topology optimization method for the stiffeners layout design of aircraft assembled structures. Multi-fastener joint loads and manufacturing constraints are consider...The purpose of this paper is to present an extended topology optimization method for the stiffeners layout design of aircraft assembled structures. Multi-fastener joint loads and manufacturing constraints are considered simultaneously. On one hand, the joint loads are calculated and constrained within a limited value to avoid the failure of fasteners. On the other hand, the manufacturing constraints of the material distribution in the machining directions of stiffeners are implemented by an improved piecewise interpolation based on a beveled cut-surface. It is proven that the objective function is strictly continuous and differentiable with respect to the piecewise interpolation. The effects of the extended method with two different constraints are highlighted by typical numerical examples. Compared with the standard topology optimization, the final designs have clearly shown the layout of stiffeners and the joint loads have been perfectly constrained to a satisfying level.展开更多
Adaptive motion/force tracking control is considered for a class of mobile manipulators with affine constraints and under-actuated joints in the presence of uncertainties in this paper. Dynamic equation of mobile mani...Adaptive motion/force tracking control is considered for a class of mobile manipulators with affine constraints and under-actuated joints in the presence of uncertainties in this paper. Dynamic equation of mobile manipulator is transformed into a controllable form based on dynamic coupling technique. In view of the asymptotic tracking idea and adaptive theory, adaptive controllers are proposed to achieve the desired control objective. Detailed simulation results confirm the validity of the control strategy.展开更多
This paper presents an extended topology optimization approach considering joint load constraints with geo-metrical nonlinearity in design of assembled structures.The geometrical nonlinearity is firstly included to re...This paper presents an extended topology optimization approach considering joint load constraints with geo-metrical nonlinearity in design of assembled structures.The geometrical nonlinearity is firstly included to reflect the structural response and the joint load distribution under large deformation.To avoid a failure of fastener joints,topology optimization is then carried out to minimize the structural end compliance in the equilibrium state while controlling joint loads intensities over fasteners.During nonlinear analysis and optimization,a novel implementation of adjoint vector sensitivity analysis along with super element condensation is introduced to address numerical instability issues.The degrees of freedom of weak regions are condensed so that their influences are excluded from the iterative Newton-Raphson(NR)solution.Numerical examples are presented to validate the efficiency and robustness of the proposed method.The effects of joint load constraints and geometrical nonlinearity are highlighted by comparing numerical optimization results.展开更多
Modal analysis is a fundamental and important task for modeling and control of the flexible manipulator. However, almost all of the traditional modal analysis methods view the flexible manipulator as a pure mechanical...Modal analysis is a fundamental and important task for modeling and control of the flexible manipulator. However, almost all of the traditional modal analysis methods view the flexible manipulator as a pure mechanical structure and neglect feedback action of joint controller. In order to study the effects of joint controller on the modal analysis of rotational flexible manipulator, a closed-loop analytical modal analysis method is proposed. Firstly, two exact boundary constraints, namely servo feedback constraint and bending moment constraint, are derived to solve the vibration partial differential equation. It is found that the stiffness and damping gains of joint controller are both included in the boundary conditions, which lead to an unconventional secular term. Secondly, analytical algorithm based on Ritz approach is developed by using Laplace transform and complex modal approach to obtain the natural frequencies and mode shapes. And then, the numerical simulations are performed and the computational results show that joint controller has pronounced influence on the modal parameters： joint controller stiffness reduces the natural frequency, while joint controller damping makes the shape phase non-zero. Furthermore, the validity of the presented conclusion is confirmed through experimental studies. These findings are expected to improve the performance of dynamics simulation systems and model-based controllers.展开更多
Joint chance constraints(JCCs)can ensure the consistency and correlation of stochastic variables when participating in decision-making.Sample average approximation(SAA)is the most popular method for solving JCCs in un...Joint chance constraints(JCCs)can ensure the consistency and correlation of stochastic variables when participating in decision-making.Sample average approximation(SAA)is the most popular method for solving JCCs in unit commitment(UC)problems.However,the typical SAA requires large Monte Carlo(MC)samples to ensure the solution accuracy,which results in large-scale mixed-integer programming(MIP)problems.To address this problem,this paper presents the partial sample average approximation(PSAA)to deal with JCCs in UC problems in multi-area power systems with wind power.PSAA partitions the stochastic variables and historical dataset,and the historical dataset is then partitioned into non-sampled and sampled sets.When approximating the expectation of stochastic variables,PSAA replaces the big-M formulation with the cumulative distribution function of the non-sampled set,thus preventing binary variables from being introduced.Finally,PSAA can transform the chance constraints to deterministic constraints with only continuous variables,avoiding the large-scale MIP problem caused by SAA.Simulation results demonstrate that PSAA has significant advantages in solution accuracy and efficiency compared with other existing methods including traditional SAA,SAA with improved big-M,SAA with Latin hypercube sampling(LHS),and the multi-stage robust optimization methods.展开更多
“双碳”目标的提出促进了绿色生产与低碳发展相结合的需求。围绕着商业园区的能量共享与低碳运行这一问题,提出了一种充电站、商业楼宇、光储电站的电-碳交易模型,研究了园区主体与电力交易中心、微网运营商、碳交易中心之间能量和信...“双碳”目标的提出促进了绿色生产与低碳发展相结合的需求。围绕着商业园区的能量共享与低碳运行这一问题,提出了一种充电站、商业楼宇、光储电站的电-碳交易模型,研究了园区主体与电力交易中心、微网运营商、碳交易中心之间能量和信息流动关系。在模型求解上,运用分布式鲁棒优化将商业园区电-碳分布式调度模型的非凸的机会约束问题转化为半正定规划问题。通过设定的3种方案从运营成本、碳排放量2个方面验证了所提方法在降成本、降碳排方面的有效性。最后,将所提方法与基于条件风险价值(conditional value at risk,CVaR)模型的线性规划方法对比,结果表明分布式鲁棒在决策结果方面更符合实际调度情况。展开更多
针对巡飞弹群协同执行侦察、打击和评估的任务分配问题,考虑任务时序约束、目标属性异构特征以及支持多弹共同执行一个任务的需求,提出一种基于联合投标的一致性包拍卖算法(Joint-bidding-based Consensus Based Bundle Algorithm,JCBB...针对巡飞弹群协同执行侦察、打击和评估的任务分配问题,考虑任务时序约束、目标属性异构特征以及支持多弹共同执行一个任务的需求,提出一种基于联合投标的一致性包拍卖算法(Joint-bidding-based Consensus Based Bundle Algorithm,JCBBA),以实现异构任务分配。在构建弹群协同“察打评”任务分配问题的组合优化模型的基础上,基于CBBA架构,定制任务包构建机制、个体竞标策略和考虑联合投标的边际收益计算方法,实现无中心通信条件下时序任务协同分配的快速鲁棒求解。多场景仿真试验结果表明,JCBBA可以在满足多种约束的前提下实现时序约束任务的合理分配,性能对比试验结果表明JCBBA能够更好地权衡协同任务分配的求解时效性和结果最优性,求解耗时相比一致性联盟算法减少约40%。展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.51175069,51205052)State Key Laboratory of Robotics of China(Grant No.2012-O16)Basic Science and Research Project of Chinese National University,China(Grant No.N140304004)
文摘In order to obtain a simple way for the force analysis of metamorphic mechanisms, the systematic method to unify the force analysis approach of metamorphic mechanisms as that of conventional planar mechanisms is proposed. A force analysis method of metamorphic mechanisms is developed by transforming the augmented Assur groups into Assur groups, so that the force analysis problem of metamorphic mechanisms is converted into the force analysis problems of conventional planar mechanisms. The constraint force change rules and values of metamorphic joints are obtained by the proposed method, and the constraint force analysis equations of revolute metamorphic joints in augmented Assur group RRRR and prismatic metamorphic joints in augmented Assur group RRPR are deduced. The constraint force analysis is illustrated by the constrained spring force design of paper folding metamorphic mechanism, and its metamorphic working process is controlled by the spring force and geometric constraints of metamorphic joints. The results of spring force show that developped design method and approach are feasible and practical. By transforming augmented Assur groups into Assur groups, a new method for the constraint force analysis of metamorphic joints is proposed firstly to provide the basis for dynamic analysis of metamorphic mechanism.
基金supported by National Natural Science Foundation of China (Nos. 11432011, 11620101002)National key research and development program of China (No. 2017YFB1102800)Key Research and Development Program of Shaanxi, China (No. S2017-ZDYF-ZDXM-GY-0035)
文摘The purpose of this paper is to present an extended topology optimization method for the stiffeners layout design of aircraft assembled structures. Multi-fastener joint loads and manufacturing constraints are considered simultaneously. On one hand, the joint loads are calculated and constrained within a limited value to avoid the failure of fasteners. On the other hand, the manufacturing constraints of the material distribution in the machining directions of stiffeners are implemented by an improved piecewise interpolation based on a beveled cut-surface. It is proven that the objective function is strictly continuous and differentiable with respect to the piecewise interpolation. The effects of the extended method with two different constraints are highlighted by typical numerical examples. Compared with the standard topology optimization, the final designs have clearly shown the layout of stiffeners and the joint loads have been perfectly constrained to a satisfying level.
基金supported by National Natural Science Foundation of China (Nos.61273091 and 61403228)Project of Taishan Scholar of Shandong Province of ChinaPh.D.Programs Foundation of Ministry of Education of China (No.20123705110002)
文摘Adaptive motion/force tracking control is considered for a class of mobile manipulators with affine constraints and under-actuated joints in the presence of uncertainties in this paper. Dynamic equation of mobile manipulator is transformed into a controllable form based on dynamic coupling technique. In view of the asymptotic tracking idea and adaptive theory, adaptive controllers are proposed to achieve the desired control objective. Detailed simulation results confirm the validity of the control strategy.
基金co-supported by National Key Research and Development Program(No.2017YFB1102800)NSFC for Excellent Young Scholars(No.11722219)Key Project of NSFC(Nos.51790171,5171101743,51735005,11620101002,and 11432011).
文摘This paper presents an extended topology optimization approach considering joint load constraints with geo-metrical nonlinearity in design of assembled structures.The geometrical nonlinearity is firstly included to reflect the structural response and the joint load distribution under large deformation.To avoid a failure of fastener joints,topology optimization is then carried out to minimize the structural end compliance in the equilibrium state while controlling joint loads intensities over fasteners.During nonlinear analysis and optimization,a novel implementation of adjoint vector sensitivity analysis along with super element condensation is introduced to address numerical instability issues.The degrees of freedom of weak regions are condensed so that their influences are excluded from the iterative Newton-Raphson(NR)solution.Numerical examples are presented to validate the efficiency and robustness of the proposed method.The effects of joint load constraints and geometrical nonlinearity are highlighted by comparing numerical optimization results.
基金Supported by National Natural Science Foundation of China(Grant No.51305039)Specialized Research Fund for the Doctoral Program of Higher Education,China(Grant No.20110005120004)+1 种基金Fundamental Research Funds for the Central Universities,China(Grant No.2014PTB-00-01)National Basic Research Program of China(973 Program,Grant No.2013CB733000)
文摘Modal analysis is a fundamental and important task for modeling and control of the flexible manipulator. However, almost all of the traditional modal analysis methods view the flexible manipulator as a pure mechanical structure and neglect feedback action of joint controller. In order to study the effects of joint controller on the modal analysis of rotational flexible manipulator, a closed-loop analytical modal analysis method is proposed. Firstly, two exact boundary constraints, namely servo feedback constraint and bending moment constraint, are derived to solve the vibration partial differential equation. It is found that the stiffness and damping gains of joint controller are both included in the boundary conditions, which lead to an unconventional secular term. Secondly, analytical algorithm based on Ritz approach is developed by using Laplace transform and complex modal approach to obtain the natural frequencies and mode shapes. And then, the numerical simulations are performed and the computational results show that joint controller has pronounced influence on the modal parameters： joint controller stiffness reduces the natural frequency, while joint controller damping makes the shape phase non-zero. Furthermore, the validity of the presented conclusion is confirmed through experimental studies. These findings are expected to improve the performance of dynamics simulation systems and model-based controllers.
基金supported by the National Natural Science Foundation of China(No.51977042)。
文摘Joint chance constraints(JCCs)can ensure the consistency and correlation of stochastic variables when participating in decision-making.Sample average approximation(SAA)is the most popular method for solving JCCs in unit commitment(UC)problems.However,the typical SAA requires large Monte Carlo(MC)samples to ensure the solution accuracy,which results in large-scale mixed-integer programming(MIP)problems.To address this problem,this paper presents the partial sample average approximation(PSAA)to deal with JCCs in UC problems in multi-area power systems with wind power.PSAA partitions the stochastic variables and historical dataset,and the historical dataset is then partitioned into non-sampled and sampled sets.When approximating the expectation of stochastic variables,PSAA replaces the big-M formulation with the cumulative distribution function of the non-sampled set,thus preventing binary variables from being introduced.Finally,PSAA can transform the chance constraints to deterministic constraints with only continuous variables,avoiding the large-scale MIP problem caused by SAA.Simulation results demonstrate that PSAA has significant advantages in solution accuracy and efficiency compared with other existing methods including traditional SAA,SAA with improved big-M,SAA with Latin hypercube sampling(LHS),and the multi-stage robust optimization methods.
文摘“双碳”目标的提出促进了绿色生产与低碳发展相结合的需求。围绕着商业园区的能量共享与低碳运行这一问题,提出了一种充电站、商业楼宇、光储电站的电-碳交易模型,研究了园区主体与电力交易中心、微网运营商、碳交易中心之间能量和信息流动关系。在模型求解上,运用分布式鲁棒优化将商业园区电-碳分布式调度模型的非凸的机会约束问题转化为半正定规划问题。通过设定的3种方案从运营成本、碳排放量2个方面验证了所提方法在降成本、降碳排方面的有效性。最后,将所提方法与基于条件风险价值(conditional value at risk,CVaR)模型的线性规划方法对比,结果表明分布式鲁棒在决策结果方面更符合实际调度情况。
文摘针对巡飞弹群协同执行侦察、打击和评估的任务分配问题,考虑任务时序约束、目标属性异构特征以及支持多弹共同执行一个任务的需求,提出一种基于联合投标的一致性包拍卖算法(Joint-bidding-based Consensus Based Bundle Algorithm,JCBBA),以实现异构任务分配。在构建弹群协同“察打评”任务分配问题的组合优化模型的基础上,基于CBBA架构,定制任务包构建机制、个体竞标策略和考虑联合投标的边际收益计算方法,实现无中心通信条件下时序任务协同分配的快速鲁棒求解。多场景仿真试验结果表明,JCBBA可以在满足多种约束的前提下实现时序约束任务的合理分配,性能对比试验结果表明JCBBA能够更好地权衡协同任务分配的求解时效性和结果最优性,求解耗时相比一致性联盟算法减少约40%。
