基于DSP的机械臂约束预测控制系统设计

针对机械臂的实时控制问题,基于约束预测控制,提出了一种机械臂实时运动控制方法。介绍了机械臂动力学模型并进行了线性化处理,以降低算法复杂度、保证实时性。设计了轨迹跟踪控制器和约束预测控制器,其中轨迹跟踪控制器采用最优反馈控制律,可确保机械臂按参考轨迹运动;而约束预测控制器则在考虑机械臂物理约束的情况下,为跟踪控制器提供最优参考轨迹。以DSP作为核心控制器,搭建了机械臂控制系统,同时给出了硬件和软件设计方法。以梯形和三次多项式轨迹为例,进行了系统功能测试,测试结果表明了所述控制系统的可行性和有效性。     

Nonlinear attitude control for a rigid spacecraft by feedback linearization

Attitude control laaw design for spacecraft large angle maneuvers is investigated in this paper. The feedback linearization technique is applied to the design of a nonlinear tracking control law. The output function to be tracked is the quaternion attitude parameter. The designed control law turns out to be a combination of attitude and attitude rate tracking commands. The attitude-only output function, therefore, leads to a stable closed-loop system following the given reference trajectory. The principal advantage of the proposed method is that it is relatively easy to produce reference trajectories and associated controller.     

Active disturbance rejection based trajectory linearization control for hypersonic reentry vehicle with bounded uncertainties

This paper investigates a novel compound control scheme combined with the advantages of trajectory linearization control (TLC) and alternative active disturbance rejection control (ADRC) for hypersonic reentry vehicle (HRV) attitude tracking system with bounded uncertainties. Firstly, in order to overcome actuator saturation problem, nonlinear tracking differentiator (TD) is applied in the attitude loop to achieve fewer control consumption. Then, linear extended state observers (LESO) are constructed to estimate the uncertainties acting on the LTV system in the attitude and angular rate loop. In addition, feedback linearization (FL) based controllers are designed using estimates of uncertainties generated by LESO in each loop, which enable the tracking error for closed-loop system in the presence of large uncertainties to converge to the residual set of the origin asymptotically. Finally, the compound controllers are derived by integrating with the nominal controller for open-loop nonlinear system and FL based controller. Also, comparisons and simulation results are presented to illustrate the effectiveness of the control strategy.     

柔性机械臂非并置式模型参考自适应控制

推导了单连杆柔性机械臂的动力学模型,研究其末端位置的模型,参考自适应控制。在推导动力学模型时,使用刚性模态和多个弹性模态使单连杆柔性机械臂等效为一个多自由度的机械多体动力系统。在研究末端位置的弹性振动抑制方法时,使用了振动主动控制方法,用线性化模型的最优状态反馈方法构造模型、Ｌｙａｐｕｎｏｖ稳定性理论推导了模型状态跟踪的自适应控制率,用ＬＱＲ方法推导末位置调节控制主。用模型状态跟踪和末端位置跟踪两     

基于线性时变模型预测控制的自主车辆轨迹跟踪控制器设计与验证

随着自动驾驶技术的快速发展,精确的轨迹跟踪已经成为汽车工业和学术领域公认的实现自主车辆运动控制的核心技术之一。为提高自主车辆轨迹跟踪的实时性与准确性,提出一种应用于自主车辆的线性时变模型预测跟踪控制器（Linear time-varying model predictive controller,LTV-MPC）设计方法。根据运动学原理建立某自主无人小车的二自由度运动学模型,其次,基于该模型构建车辆轨迹跟踪系统的误差模型并利用线性参数化理论对其进行离散化,在模型预测控制框架内将该轨迹跟踪控制器的设计转化为一个线性二次规划最优问题。在一个实际搭建的自主车辆试验平台上对所提出控制器的有效性进行不同预设参考路径轨迹下的实车验证,结果表明,该自主车辆能够对所预设的实际参考道路轨迹进行快速、准确的轨迹跟踪控制,且具有较好的行驶稳定性能。     

四轮轮毂电机驱动智能电动汽车转向失效容错控制研究

四轮轮毂电机驱动电动汽车各轮驱动力矩独立可控,可通过控制前轴左右两轮的力矩差实现前轮转向。以四轮轮毂电机驱动智能电动汽车为研究对象,针对线控转向系统执行机构失效时的轨迹跟踪和横摆稳定性协同控制问题,提出一种基于差动转向与直接横摆力矩协同的容错控制方法。该方法采用分层控制架构,上层控制器首先基于时变线性模型预测控制方法求解期望前轮转角和附加横摆力矩,然后考虑转向执行机构建模不确定性以及路面干扰,设计基于滑模变结构控制的前轮转角跟踪控制策略。下层控制器以轮胎负荷率最小化为目标,利用有效集法实现四轮转矩优化分配。最后,分别在高速换道和双移线工况下仿真验证了该控制方法的有效性和实时性。     

转向缸系统反馈线性化分析与系统解耦

为解决汽车转向缸加载控制中出现的诸如强位置干扰、多通道耦合、非线性等问题,将线性系统和非线性系统理论引入系统控制器的设计中,对各通道耦合问题开展了以前馈补偿为基础的解耦控制,所设计的前馈补偿结构简单,解耦网络阶次低;针对非线性问题提出了将非线性系统精确反馈线性化与最优控制相结合的方法,设计了基于精确反馈线性化的最优控制器,该方法将复杂的非线性系统问题转化为线性系统的综合问题,采用渐近输出跟踪方法实现系统控制。仿真结果表明:采用前馈补偿解耦控制器可以有效消除耦合,但当系统存在高度非线性时,仅采用前馈补偿解耦控制不能达到高品质的性能要求,而进一步设计的基于精确反馈线性化的最优控制器考虑系统非线性时,系统能快速、准确达到预置设定。     

多关节机器人反馈线性化双模糊滑模控制

为了提高多关节机器人轨迹跟踪控制性能,提出了一种反馈线性化双模糊滑模控制方法。该方法在对机器人非线性动力学模型反馈线性化的基础上,设计了一种双模糊滑模控制器。通过设计一个模糊控制器,根据跟踪误差和误差变化率自适应地调整滑模面的斜率,从而加快响应速度。通过设计另一个模糊控制器,根据滑模面自适应地调整滑模控制的切换控制部分,从而减弱抖振。利用李亚普诺夫定理证明了控制系统的稳定性。针对空间三关节机器人进行了仿真实验,结果表明了所提方法的有效性。     

Modeling and output tracking of transverse flux permanent magnet machines using high gain observer and RBF neural network

This paper deals with modeling and adaptive output tracking of a transverse flux permanent magnet machine as a nonlinear system with unknown nonlinearities by utilizing high gain observer and radial basis function networks. The proposed model is developed based on computing the permeance between rotor and stator using quasiflux tubes. Based on this model, the techniques of feedback linearization and H_∞ control are used to design an adaptive control law for compensating the unknown nonlinear parts, such as the effect of cogging torque, as a disturbance is decreased onto the rotor angle and angular velocity tracking performances. Finally, the capability of the proposed method in tracking both the angle and the angular velocity is shown in the simulation results.     

Reference trajectory analysis and trajectory control by bank angle for re-entry vehicle

The re-entry problem consists of guidance design and trajectory control. This paper summarizes the detailed relationships between the velocity, drag acceleration and altitude in determining reference trajectories. The computational issues are also addressed, and the performance of the proposed simple nonlinear control of a bank angle for the longitudinal/lateral trajectory is demonstrated. In particular, the fixed bank angle methods that can reduce the drag acceleration errors at low-speeds are proposed. The importance of bank reversals with respect to the azimuth errors is also elucidated.     

基于T-S模糊变权重MPC的智能车轨迹跟踪控制

为了协调智能驾驶车辆的轨迹跟踪精确性和稳定性,提高控制算法对不同工况的自适应能力,提出基于Takagi-Sugeno模糊变权重模型预测控制(Takagi-Sugeno fuzzy model predictive control,T-S FMPC)的轨迹跟踪控制策略。以前轮转角为控制变量建立MPC控制,并以实时横向位移误差和横摆角误差为模糊输入,通过T-S模糊控制在线优化MPC目标函数权重,协调权重矩阵对轨迹跟踪精确性和稳定性的影响。基于Carsim建立分布式驱动电动汽车的整车动力学模型,基于Simulink建立控制策略,通过双移线工况仿真及实车试验,验证了所提控制策略的有效性。仿真结果表明,相比于传统MPC控制,所提出的T-S模糊变权重MPC控制可降低横向位移误差达62.24%,有效提高轨迹跟踪精度;并且可使前轮转角波动减小37.46%、横摆角误差减小84.19%,显著增强轨迹跟踪稳定性;试验结果表明,在20 km/h、沥青路面双移线工况下,横向位移误差在0.12 m以内,横摆角误差在1°以内,且前轮转角控制曲线平滑,说明所提算法具有良好的控制效果和实用性。     

基于最优预瞄的智能车变道控制

针对智能车主动变道过程中的轨迹跟踪控制问题,基于“预瞄-跟随”控制理论及“车辆-道路”模型提出了最优预瞄轨迹跟踪控制模型,并依据线性二次型调节器(LQR)理论设计了轨迹跟踪控制器,获得了最优转向盘转角输入,以实现智能车变道轨迹跟踪。在MATLAB/Simulink和CarSim的联合仿真环境下构建了智能车的变道决策模块、变道参考轨迹模块和跟踪控制模块,实现了智能车在30 km/h、50 km/h和70 km/h速度下的仿真验证。结合实车测试结果验证了所设计控制器的精确度和稳定性。     

Continuous high order sliding mode controller design for a flexible air-breathing hypersonic vehicle

This paper investigates the problem of tracking control with uncertainties for a flexible air-breathing hypersonic vehicle (FAHV). In order to overcome the analytical intractability of this model, an Input–Output linearization model is constructed for the purpose of feedback control design. Then, the continuous finite time convergence high order sliding mode controller is designed for the Input–Output linearization model without uncertainties. In addition, a nonlinear disturbance observer is applied to estimate the uncertainties in order to compensate the controller and disturbance suppression, where disturbance observer and controller synthesis design is obtained. Finally, the synthesis of controller and disturbance observer is used to achieve the tracking for the velocity and altitude of the FAHV and simulations are presented to illustrate the effectiveness of the control strategies.     

Lateral control of autonomous vehicle by yaw rate feedback

In the autonomous vehicle, the reference lane is continually detected by machine vision system. And then the vehicle is steered to follow the reference yaw rates which are generated by the deviations of lateral distance and the yaw angle between a vehicle and the reference lane. To cope with the steering delay and the side-slip of vehicle, PI controller is introduced by yaw rate feedback and tuned from the simulation where the vehicle is modeled as 2 DOF and 79 DOF and verified by the results of an actual vehicle test. The lateral control algorithm by yaw rate feedback has good performances of lane tracking and passenger comfort.     

Model-based reference trajectory generation for tip-based learning controller

The non-minimum phase characteristic of a flexible manipulator makes tracking control of its tip difficult The level of the tip tracking performance of a flexible manipulator is significantly affected by the characteristics of the tip reference trajectory as well as the characteristics of the flexible manipulator system This paper addresses the question of how to best specify a reference trajectory for the tip of a flexible mampulator to follow in order to achieve the objectives of reducing tip tracking error, residual tip vibration, and the required actuation effort at the manipulator joint A novel method of tip-based learning controller for the flexible manipulator system is proposed in the paper, where a model of the flexible manipulator system with a command shaping filter is used to generate a smooth and realizable tip reference trajectory for a tip-based learning controller     

Design,implementation, and test of skid steering-based autonomous driving controller for a robotic vehicle with articulated suspension

This paper describes an autonomous driving control algorithm based on skid steering for a Robotic Vehicle with Articulated Suspension (RVAS). The driving control algorithm consisted of four parts: speed controller for following the desired speed, trajectory tracking controller to track the desired trajectory, longitudinal tire force distribution algorithm which determines the optimal desired longitudinal tire force and wheel torque controller which determines the wheel torque command at each wheel to keep the slip ratio below the limit value as well as to track the desired tire force. The longitudinal and vertical tire force estimators were designed for optimal tire force distribution and wheel slip control. The dynamic model of the RVAS is validated using vehicle test data. Simulation and vehicle tests were conducted in order to evaluate the proposed driving control algorithm. Based on the simulation and test results, the proposed driving controller was shown to produces satisfactory trajectory tracking performance.     

基于奇异摄动的柔性机械手预测控制

讨论了柔性机械手末端位置的控制问题。采用奇异摄动方法将柔性机械臂系统动力学方程分解为慢变(刚性 )和快变 (弹性 )两个子系统。给出了一种预测控制与 I/ O反馈线性化相结合的混合控制方法。该方法采用预测控制消除柔性机械手的弹性振动 ,可避免逆动力学和 I/ O反馈线性化控制遇到的零动力学不稳定问题。通过一个柔性机械手的仿真表明 ,本文提出的控制方法可实现柔性机械手末端轨迹的准确跟踪 ,同时能消除柔性机械手的弹性振动。     

Load carrying capacity of flexible joint manipulators with feedback linearization

A computational technique for obtaining the maximum load carrying capacity of robotic manipulators with joint elasticity, subject to accuracy and actuators constraints, is described herein. A feedback linearization technique is used to minimize end-effector deflection. An inversion algorithm is employed for the synthesis of a dynamic feedback control law that provides input-output decoupling and full state linearization. The linearizing input transformations and the corresponding state diffeomorphisms are presented. The proposed technique is then applied to a flexible joint robot. Linearizing control law is been expressed in terms of different sets of model variables and their derivatives. As a result, different tracking errors and torques are introduced in the robot-given trajectory and different load carrying capacities are obtained.     

Sliding mode based trajectory linearization control for hypersonic reentry vehicle via extended disturbance observer

This paper proposes a novel hybrid control framework by combing observer-based sliding mode control (SMC) with trajectory linearization control (TLC) for hypersonic reentry vehicle (HRV) attitude tracking problem. First, fewer control consumption is achieved using nonlinear tracking differentiator (TD) in the attitude loop. Second, a novel SMC that employs extended disturbance observer (EDO) to counteract the effect of uncertainties using a new sliding surface which includes the estimation error is integrated to address the tracking error stabilization issues in the attitude and angular rate loop, respectively. In addition, new results associated with EDO are examined in terms of dynamic response and noise-tolerant performance, as well as estimation accuracy. The key feature of the proposed compound control approach is that chattering free tracking performance with high accuracy can be ensured for HRV in the presence of multiple uncertainties under control constraints. Based on finite time convergence stability theory, the stability of the resulting closed-loop system is well established. Also, comparisons and extensive simulation results are presented to demonstrate the effectiveness of the control strategy.     

Fixed-time output feedback trajectory tracking control of marine surface vessels subject to unknown external disturbances and uncertainties

This paper proposes a novel fixed-time output feedback control scheme for trajectory tracking of marine surface vessels (MSVs) subject to unknown external disturbances and uncertainties. A fixed-time extended state observer (FESO) is proposed to estimate unknown lumped disturbances and unmeasured velocities, and the observation errors will converge to zero in fixed time. Based on the estimated values, a novel fixed-time trajectory tracking controller is designed for an MSV to track a time-varying reference trajectory by the extension of an adding a power integrator (API), and the tracking errors can converge to zero in fixed time as well. Additionally, the convergence time of the controller and the FESO is independent of initial state values. Finally, simulation results and comparisons illustrate the superiority of the proposed control scheme.