In this paper, the car-like robot kinematic model trajectory tracking and control problem is revisited by exploring an optimal analytical solution which guarantees the global exponential stability of the tracking erro...In this paper, the car-like robot kinematic model trajectory tracking and control problem is revisited by exploring an optimal analytical solution which guarantees the global exponential stability of the tracking error. The problem is formulated in the form of tracking error optimization in which the quadratic errors of the position, velocity, and acceleration are minimized subject to the rear-wheel car-like robot kinematic model. The input-output linearization technique is employed to transform the nonlinear problem into a linear formulation. By using the variational approach, the analytical solution is obtained, which is guaranteed to be globally exponentially stable and is also appropriate for real-time applications. The simulation results demonstrate the validity of the proposed mechanism in generating an optimal trajectory and control inputs by evaluating the proposed method in an eight-shape tracking scenario.展开更多
This paper presents the design of decentralized repetitive control （RC） for multi-input multi-output （MIMO） systems. An optimization method is used to obtain a RC compensator that ensures system stability and good...This paper presents the design of decentralized repetitive control （RC） for multi-input multi-output （MIMO） systems. An optimization method is used to obtain a RC compensator that ensures system stability and good tracking performance. The designed compensator is in the form of a stable, low order, and causal filter, in which the compensator can be implemented separately without being merged with the RC internal model. This will reduce complexity in the implementation. Simulation results and comparison study are given to demonstrate the effectiveness of the proposed design. The novelty of design is also verified in experiments on a 2 degrees of freedom （DOF） robot.展开更多
In this paper, an efficient computational approach is proposed to solve the discrete time nonlinear stochastic optimal control problem. For this purpose, a linear quadratic regulator model, which is a linear dynamical...In this paper, an efficient computational approach is proposed to solve the discrete time nonlinear stochastic optimal control problem. For this purpose, a linear quadratic regulator model, which is a linear dynamical system with the quadratic criterion cost function, is employed. In our approach, the model-based optimal control problem is reformulated into the input-output equations. In this way, the Hankel matrix and the observability matrix are constructed. Further, the sum squares of output error is defined. In these point of views, the least squares optimization problem is introduced, so as the differences between the real output and the model output could be calculated. Applying the first-order derivative to the sum squares of output error, the necessary condition is then derived. After some algebraic manipulations, the optimal control law is produced. By substituting this control policy into the input-output equations, the model output is updated iteratively. For illustration, an example of the direct current and alternating current converter problem is studied. As a result, the model output trajectory of the least squares solution is close to the real output with the smallest sum squares of output error. In conclusion, the efficiency and the accuracy of the approach proposed are highly presented.展开更多
为提高频控阵-多输入多输出(frequency diverse array multiple-input and multiple-output,FDA-MIMO)雷达系统的抗干扰能力,提出一种基于双子脉冲模式的FDA-MIMO雷达接收滤波器-发射频偏联合优化设计方法。在传统脉冲的基础上,引入双...为提高频控阵-多输入多输出(frequency diverse array multiple-input and multiple-output,FDA-MIMO)雷达系统的抗干扰能力,提出一种基于双子脉冲模式的FDA-MIMO雷达接收滤波器-发射频偏联合优化设计方法。在传统脉冲的基础上,引入双子脉冲发射模式并建立相关信号模型。在此基础上,建立以最大信干噪比(signal-to-interference-plus-noise ratio,SINR)为准则的接收滤波器-发射频偏联合优化问题。为了得到最优的接收-发射滤波器设计方案,引入一种迭代优化算法,将该优化问题拆分为接收滤波器优化和发射频偏优化两个独立的子问题。为进一步完成对发射频偏的设计,将其转化为关于发射导向矢量的设计问题,采用半正定松弛和随机方法,并通过发射导向矢量和频偏的数学关系获得频偏的最终设计方案。最后,通过仿真实验验证了所提双子脉冲FDA-MIMO雷达模式和接收滤波器-发射频偏联合优化设计方法对提高雷达系统抗干扰能力的有效性。展开更多
Dual-hop cooperative Multiple-Input Multiple-Output (MIMO) network with multi-relay cooperative communication is introduced. Power allocation problem with Amplify-and-Forward (AF) and Selective Decode-and-Forward (SDF...Dual-hop cooperative Multiple-Input Multiple-Output (MIMO) network with multi-relay cooperative communication is introduced. Power allocation problem with Amplify-and-Forward (AF) and Selective Decode-and-Forward (SDF) strategies in multi-node scenario are formulated and solved respectively. Optimal power allocation schemes that maximize system capacity with AF strategy are presented. In addition, optimal power allocation methods that minimize asymptotic Symbol Error Rate (SER) with SDF cooperative protocol in multi-node scenario are also proposed. Furthermore, performance comparisons are provided in terms of system capacity and approximate SER. Numerical and simulation results confirm our theoretical analysis. It is revealed that, maximum system capacity could be obtained when powers are allocated optimally with AF protocol, while minimization of system's SER could also be achieved with optimum power allocation in SDF strategy. In multi-node scenario, those optimal power allocation algorithms are superior to conventional equal power allocation schemes.展开更多
文章结合多输入多输出(Multiple Input Multiple Output,MIMO)技术,提出针对低截获概率(Low Probability of Intercept,LPI)通信的传输模式优化、波束成形、功率控制与信道估计等方法,旨在提高系统的抗干扰能力和信号传输效率。仿真结...文章结合多输入多输出(Multiple Input Multiple Output,MIMO)技术,提出针对低截获概率(Low Probability of Intercept,LPI)通信的传输模式优化、波束成形、功率控制与信道估计等方法,旨在提高系统的抗干扰能力和信号传输效率。仿真结果表明,相较于传统单天线LPI系统,基于MIMO的LPI通信系统在复杂信道环境下实现了显著的性能提升,尤其在高信噪比条件下展现出更好的抗衰落能力和吞吐量。该研究为LPI通信技术的发展提供了新的思路,为未来的无线安全通信等领域提供了技术支持和理论依据。展开更多
基金supported by the Air Force Research Laboratory and Office of the Secretary of Defense(OSD)(FA8750-15-2-0116)the US Department of Transportation(USDOT)Research and Innovative Technology Administration(RITA)under University Transportation Center(UTC)Program(DTRT13-G-UTC47)
文摘In this paper, the car-like robot kinematic model trajectory tracking and control problem is revisited by exploring an optimal analytical solution which guarantees the global exponential stability of the tracking error. The problem is formulated in the form of tracking error optimization in which the quadratic errors of the position, velocity, and acceleration are minimized subject to the rear-wheel car-like robot kinematic model. The input-output linearization technique is employed to transform the nonlinear problem into a linear formulation. By using the variational approach, the analytical solution is obtained, which is guaranteed to be globally exponentially stable and is also appropriate for real-time applications. The simulation results demonstrate the validity of the proposed mechanism in generating an optimal trajectory and control inputs by evaluating the proposed method in an eight-shape tracking scenario.
文摘This paper presents the design of decentralized repetitive control （RC） for multi-input multi-output （MIMO） systems. An optimization method is used to obtain a RC compensator that ensures system stability and good tracking performance. The designed compensator is in the form of a stable, low order, and causal filter, in which the compensator can be implemented separately without being merged with the RC internal model. This will reduce complexity in the implementation. Simulation results and comparison study are given to demonstrate the effectiveness of the proposed design. The novelty of design is also verified in experiments on a 2 degrees of freedom （DOF） robot.
文摘In this paper, an efficient computational approach is proposed to solve the discrete time nonlinear stochastic optimal control problem. For this purpose, a linear quadratic regulator model, which is a linear dynamical system with the quadratic criterion cost function, is employed. In our approach, the model-based optimal control problem is reformulated into the input-output equations. In this way, the Hankel matrix and the observability matrix are constructed. Further, the sum squares of output error is defined. In these point of views, the least squares optimization problem is introduced, so as the differences between the real output and the model output could be calculated. Applying the first-order derivative to the sum squares of output error, the necessary condition is then derived. After some algebraic manipulations, the optimal control law is produced. By substituting this control policy into the input-output equations, the model output is updated iteratively. For illustration, an example of the direct current and alternating current converter problem is studied. As a result, the model output trajectory of the least squares solution is close to the real output with the smallest sum squares of output error. In conclusion, the efficiency and the accuracy of the approach proposed are highly presented.
文摘为提高频控阵-多输入多输出(frequency diverse array multiple-input and multiple-output,FDA-MIMO)雷达系统的抗干扰能力,提出一种基于双子脉冲模式的FDA-MIMO雷达接收滤波器-发射频偏联合优化设计方法。在传统脉冲的基础上,引入双子脉冲发射模式并建立相关信号模型。在此基础上,建立以最大信干噪比(signal-to-interference-plus-noise ratio,SINR)为准则的接收滤波器-发射频偏联合优化问题。为了得到最优的接收-发射滤波器设计方案,引入一种迭代优化算法,将该优化问题拆分为接收滤波器优化和发射频偏优化两个独立的子问题。为进一步完成对发射频偏的设计,将其转化为关于发射导向矢量的设计问题,采用半正定松弛和随机方法,并通过发射导向矢量和频偏的数学关系获得频偏的最终设计方案。最后,通过仿真实验验证了所提双子脉冲FDA-MIMO雷达模式和接收滤波器-发射频偏联合优化设计方法对提高雷达系统抗干扰能力的有效性。
基金Supported by National Natural Science Foundation of China (NSFC) (No. 60972039)National High Technology Research and Development Program of China (No.2009AA01Z241)Innovation Program for Ph.D. and Postgraduate Candidates in Jiangsu Province (No.CX09B_147Z)
文摘Dual-hop cooperative Multiple-Input Multiple-Output (MIMO) network with multi-relay cooperative communication is introduced. Power allocation problem with Amplify-and-Forward (AF) and Selective Decode-and-Forward (SDF) strategies in multi-node scenario are formulated and solved respectively. Optimal power allocation schemes that maximize system capacity with AF strategy are presented. In addition, optimal power allocation methods that minimize asymptotic Symbol Error Rate (SER) with SDF cooperative protocol in multi-node scenario are also proposed. Furthermore, performance comparisons are provided in terms of system capacity and approximate SER. Numerical and simulation results confirm our theoretical analysis. It is revealed that, maximum system capacity could be obtained when powers are allocated optimally with AF protocol, while minimization of system's SER could also be achieved with optimum power allocation in SDF strategy. In multi-node scenario, those optimal power allocation algorithms are superior to conventional equal power allocation schemes.
文摘文章结合多输入多输出(Multiple Input Multiple Output,MIMO)技术,提出针对低截获概率(Low Probability of Intercept,LPI)通信的传输模式优化、波束成形、功率控制与信道估计等方法,旨在提高系统的抗干扰能力和信号传输效率。仿真结果表明,相较于传统单天线LPI系统,基于MIMO的LPI通信系统在复杂信道环境下实现了显著的性能提升,尤其在高信噪比条件下展现出更好的抗衰落能力和吞吐量。该研究为LPI通信技术的发展提供了新的思路,为未来的无线安全通信等领域提供了技术支持和理论依据。
