基于新颖自适应方法的微振动陀螺仪研究

针对微振动陀螺仪存在的制造误差以及本身参数易受环境影响,从而导致输入角速率难以测量的问题,提出了一种新颖的自适应方法来获取输入的角速率以及微陀螺仪的各项参数.该方法通过对微陀螺仪的数学模型进行变换,设计出一种新型的自适应辨识嚣,在线实时更新微陀螺仪角速率估计值.估计值的自适应律基于李雅普诺夫方法设计,保证了辨识器的全局...     

滑动及侧滑影响下的移动机器人轨迹跟踪控制

对受滑动及侧滑影响的移动机器人轨迹跟踪控制问题进行研究。在动力学部分,通过模糊系统逼近系统中的未知非线性,H_∞控制对滑动和侧滑干扰因素的补偿,利用Lyapunov函数推导出模糊参数的自适应律,设计出基于动力学的自适应模糊控制器。在运动学部分,设计逆运动学控制器,处理移动机器人实际位置与期望位置的误差,得到移动机器人运动的期望速度。将逆运动学控制器与自适应模糊控制器级联,并通过Lyapunov方法证明控制系统的稳定性。与自适应动力学控制器进行比较。仿真结果表明:在滑动及侧滑的影响下提出的策略具有较好的轨迹跟踪性能。     

基于参数估计误差的鲁棒自适应律设计及验证

针对传统自适应控制系统设计的自适应律参数收敛慢进而影响控制系统瞬态性能的问题,研究一类新的基于参数估计误差修正的鲁棒自适应律设计.首先引入滤波操作给出参数估计误差的提取方法,构建出含参数估计误差修正项的自适应律,进而将该自适应律用于控制器设计和分析中,可同时实现控制误差和参数估计误差指数收敛.对比分析了几类传统自适应律和所提出自适应律的收敛性和鲁棒性,并给出了保证参数收敛所需持续激励条件的一种直观、简便的在线判别方法.数值仿真及基于自制三自由度直升机系统俯仰轴实验结果表明,基于参数误差修正的自适应律及控制器可得到优于传统自适应方法的跟踪控制和参数估计性能.     

机动再入飞行器自适应自动驾驶仪设计

解决了机动再入飞行器在气动系数变化范围大和气动耦合严重等恶劣条件下的姿态和过载控制问题. 为了能充分利用飞行器可测量信息提高系统自适应能力, 提出了滚动通道状态方程参数辨识—级点配置—前馈补偿自适应控制和横向通道基于攻角反馈以过载为主控信号的变参数自适应控制的自动驾驶仪设计方法. 通过对某飞行器的制导控制系统仿真, 可以看出该自动驾驶仪使飞行器有很好的飞行性能.     

受侧滑和滑移影响的移动机器人自抗扰控制

对存在侧滑和滑移干扰问题的轮式移动机器人轨迹跟踪问题进行研究。首先利用移动机器人系统的运动学模型,通过设计其辅助运动学控制器,使得机器人的辅助速度渐近收敛到期望速度;然后利用反步法思想设计了基于动力学模型的一阶线性自抗扰控制（LADRC）,通过扩张状态观测器（ESO）实时估计和补偿机器人运行过程中的侧滑和滑移干扰,使得机器人的实际速度渐近收敛到辅助速度;最终使得移动机器人的轨迹误差渐近趋近于零。通过仿真及实验验证了所设计方法的有效性。     

地面和空间机械臂的动力学等效条件与控制相似律

针对如何在地面机械臂上有效验证空间机械臂控制律的问题,本文研究空间机械臂和地面机械臂系统间的动力学等效条件和控制相似律.首先,基于量纲分析研究地面机械臂和空间机械臂之间的动力学等效条件,并基于等效条件设计地面机械臂系统.其次,基于量纲分析建立空间和地面机械臂系统间的控制相似律,设计的空间机械臂控制律通过控制相似律将可以转化为地面机械臂相应的控制律.最后,考虑地面机械臂基座往往无法和空间机械臂的基座航天器一样进行全6自由度运动,以及地面机械臂运动时受到重力影响,使得地面机械臂不再满足动力学等效条件,基于反馈线性化技术设计一种地面机械臂的动力学误差补偿策略,使得地面机械臂和空间机械臂具有相似的闭环动力学行为.这样,空间机械臂的控制律可以在设计的地面机械臂上进行验证,仿真中以在地面机械臂上验证空间机械臂的PID控制器为例说明所提方法的有效性.     

非线性离散时间系统的自适应模糊补偿控制

针对一类非线性离散时间系统,提出一种自适应模糊逻辑补偿控制方案.控制律由跟踪控制律和逼近误差补偿控制律两部分组成,利用模糊逻辑系统对系统参数扰动和外界干扰进行自适应补偿,由模糊滑模控制律实现对模糊逻辑系统逼近误差的进一步补偿.所设计的控制器可保证闭环系统一致最终有界.将该控制器用于月球探测车动态转向系统中,仿真结果表明了该方法的有效性.     

欠驱动船舶神经网络自适应路径跟踪控制

针对模型参数未知的欠驱动船舶路径跟踪问题,将神经网络技术与反演设计法相结合,提出一种神经网络稳定自适应控制方法。首先根据运动学误差方程和线性变换确定辅助的前进速度和艏摇角,然后利用神经网络逼近技术对模型中任意不确定因素进行补偿,设计自适应控制律,使得实际的前进速度和艏摇角分别收敛到辅助值。应用Lyapunov函数证明了船舶路径跟踪闭环系统的误差信号最终一致有界。仿真结果表明,利用设计的控制律可以迫使欠驱动船舶跟踪曲线和直线路径,并且具有较强的鲁棒性。     

基于混合滑模控制器和反正切观测器的SPMSM直接转矩控制

针对基于传统PI控制的表贴式永磁同步电机(SPMSM)直接转矩控制系统抖振和相位延迟等问题,在转速环节设计新型趋近律,采用模糊自适应方法,实现趋近律参数的动态调节,并通过Lyapunov方法证明稳定性.利用super-twisting滑模策略生成参考电压矢量,完成混合滑模控制器的设计,建立基于反正切函数的滑模观测器,并对转子位置进行合理补偿.仿真实验表明,与PI控制、基于指数趋近律的滑模控制器相比,所设计的控制器在电机空载起动和外加干扰情况下均能有效提高系统响应,显著降低抖振,与其他模型参考自适应观测器相比,所设计观测器能有效减小相位延迟,转子位置辨识结果更准确.     

模块化反步自适应大机动飞行控制

针对飞机大机动飞行时模型非线性和参数不确定性的特点,提出一种输入状态稳定反步自适应控制的模块化设计方法.基于模块化设计思想,设计一个输入状态稳定的反步控制器,保证在输入有界情况下系统状态的有界特性.基于最小二乘算法设计参数自适应律和滤波器的辨识器模块,保证独立于输入状态稳定控制器之外的参数误差及其导数有界,并利用一种基于免疫克隆原理的改进粒了群算法优化固定参数,改善动态性能.仿真结果表明了所提出算法的有效性.     

Tire–road friction coefficient and tire cornering stiffness estimation based on longitudinal tire force difference generation

A sequential tire cornering stiffness coefficient and tire–road friction coefficient (TRFC) estimation method is proposed for some advanced vehicle architectures, such as the four-wheel independently-actuated (FWIA) electric vehicles, where longitudinal tire force difference between the left and right sides of the vehicle can be easily generated. Such a tire force difference can affect the vehicle yaw motion, and can be utilized to estimate the tire cornering stiffness coefficient and TRFC. The proposed tire cornering stiffness coefficient and TRFC identification method has the potential of estimating these parameters without affecting the vehicle desired motion control and trajectory tracking objectives. Simulation and experimental results with a FWIA electric vehicle show the effectiveness of the proposed estimation method.     

Identification of vehicle parameters using stationary driving maneuvers

Using the velocity dependent static gains of the one track model it is shown how special combinations of parameters like cornering stiffness and center of gravity can be estimated. Driving with various speed and a constant cornering radius it is possible to estimate three different gains by measurement of the lateral acceleration, the yaw rate and the vehicle slip angle without knowing the moment of inertia of the vehicle. Results are shown for different measurements of a passenger car.     

A Tire Stiffness Backstepping Observer Dedicated to All-Terrain Vehicle Rollover Prevention

Most active devices focused on vehicle stability concern on-road cars and cannot be applied satisfactorily in an off-road context, since the variability and the non-linearities of tire/ground contact are often neglected. In previous work, a rollover indicator devoted to light all-terrain vehicles accounting for these phenomena has been proposed. It is based on the prediction of the lateral load transfer. However, such an indicator requires the on-line knowledge of the tire cornering stiffness. Therefore, in this paper, an adapted backstepping observer, making use only of yaw rate measurement, is designed to estimate tire cornering stiffness and to account for its non-linearity. The capabilities of such an observer are demonstrated and discussed through both advanced simulations and actual experiments.     

New adaptive approaches to real-time estimation of vehicle sideslip angle

This paper presents new approaches to the identification of the vehicle sideslip angle and the road bank angle in real-time. The major challenge is that the vehicle sideslip angle and the road bank angle are coupled together with the system uncertainties, such as variations in the vehicle parameters and the tire cornering stiffness. To resolve this difficulty, the proposed estimation algorithms identify the uncertain vehicle parameters using the sensor measurements such as the steering angle, the lateral acceleration and the yaw rate, and then estimate the vehicle sideslip angle and the road bank angle via a simple algebraic relationship in real time. In particular, the use of the lateral G sensor signal makes it possible to identify the cornering stiffness and vehicle sideslip angle without any a priori knowledge on the road bank angle. The performance of the proposed algorithms is verified through simulation and experimental results.     

Local asymmetrical corner trajectory smoothing with bidirectional planning and adjusting algorithm for CNC machining

The linear motion command (G01) is a widely used command format in CNC machining. However, the tangential direction discontinuity at the corner junction will cause velocity fluctuations and excite the structural vibration of machine tools. Corner smoothing methods with controlled tolerance are used to obtain continuous smooth motion. Typically, most methods generate a symmetrical cornering trajectory around the angle bisector, and the trajectory generally decelerates first and then accelerates, which limits the velocity increase. In this paper, a novel local asymmetrical corner trajectory smoothing method is proposed, which can realize accelerated/decelerated cornering transition. The proposed method can obtain the analytical solution in one step, which is different from two-step geometric-based corner path smoothing, and can generate the same cornering trajectory in back-and-forth parallel toolpath. In addition, this paper proposes a bidirectional planning and adjusting algorithm for the situation where smoothed cornering paths are close to each other or even overlap. The algorithm can generate a jerk-limited trajectory by coordinating the cornering error of adjacent corners, while respecting the user-specified tolerance. Experimental results demonstrate the effectiveness of the proposed method in contour accuracy and cycle time for CNC machining along short-segmented toolpath.     

Estimation of vehicle sideslip, tire force and wheel cornering stiffness

This paper presents a process for the estimation of tire–road forces, vehicle sideslip angle and wheel cornering stiffness. The method uses measurements (yaw rate, longitudinal/lateral accelerations, steering angle and angular wheel velocities) only from sensors which can be integrated or have already been integrated in modern cars. The estimation process is based on two blocks in series: the first block contains a sliding-mode observer whose principal role is to calculate tire–road forces, while in the second block an extended Kalman filter estimates sideslip angle and cornering stiffness. More specifically, this study proposes an adaptive tire-force model that takes variations in road friction into account. The paper also presents a study of convergence for the sliding-mode observer. The estimation process was applied and compared to real experimental data, in particular wheel force measurements. The vehicle mass is assumed to be known. Experimental results show the accuracy and potential of the estimation process.     

汽车操纵稳定性稳态响应参数的单位与量纲

针对表征汽车操纵稳定性状态的稳定性因数等参数的单位规定比较混乱的现状,根据角度物理量有单位但无量纲的特点,在轮胎侧偏刚度取两种不同单位的情况下,对汽车转向稳态响应的稳定性因数及稳态横摆角速度增益等重要参数的单位及量纲进行了全面分析.     

非独立悬架车辆自激摆振的数值仿真分析

基于一个三自由度的转向系统模型,利用数值仿真方法分析了横拉杆刚度、主销后倾角、转向机刚度、轮胎侧偏刚度、轮胎拖距、转向机阻尼、绕主销当量阻尼等参数对载重汽车自激型摆振的影响.仿真分析的结果表明,上述参数发生变化时,可诱发自激摆振,但车速也是影响摆振的关键因素之一.在确定的系统参数和车速下,初始激励不仅可能诱发稳定的自激摆振,还可能是发散的运动.与受迫型自激摆振不同,自激型摆振的频率变化与车速的变化并不一致.     

智能车辆横向控制研究

本文分析了智能车辆横向控制特性，说明了目前一些研究中的不足，并探讨了 模糊控制方法．仿真结果表明，该算法对纵向速度、轮胎侧偏刚度以及载荷等明显影响车辆 横向运动特性的三个关键因素具有良好的适应性能．     

Hierarchical control for cornering stability of dual-motor RWD vehicles with electronic differential system using PSO optimized SOSMC method

This paper proposes a novel control scheme with a three-layer hierarchical structure to improve the cornering stability of the dual-motor rear-wheel drive (RWD) vehicles with the electronic differential system (EDS). The proposed hierarchical structure for the control system includes the observing layer, control layer, and actuation layer. In the observing layer, the driver model is designed to obtain the nominal steering angle, and the state observer is designed to obtain the yaw angle which cannot be easily measured. Then, particle swarm optimization (PSO) and second order sliding mode control (SOSMC) are employed in the control layer. The SOSMC part is used to design the control law to eliminate the chattering problem in the sliding mode algorithm, and the PSO part is used to obtain the optimal weights in the sliding mode surface to meet the minimum sideslip angle error and yaw rate error. The actuation layer allocates the corrected yaw moment by distributing the driving force to each independent driving wheel. Finally, the numerical tests are carried out under the double line change (DLC) maneuver. The results show that the proposed control system can effectively improve the cornering stability of the dual-motor RWD vehicles and reduce their motor power consumption.