白国星, 伊力夏提·伊力哈木江, 付薛洁, 孟 宇, 刘立, 顾青. 基于前馈模型预测控制的类车机器人路径跟踪[J]. 工程科学学报. DOI: 10.13374/j.issn2095-9389.2023.10.20.001
引用本文: 白国星, 伊力夏提·伊力哈木江, 付薛洁, 孟 宇, 刘立, 顾青. 基于前馈模型预测控制的类车机器人路径跟踪[J]. 工程科学学报. DOI: 10.13374/j.issn2095-9389.2023.10.20.001
Path tracking for car-like robots based on feed-forward model predictive control[J]. Chinese Journal of Engineering. DOI: 10.13374/j.issn2095-9389.2023.10.20.001
Citation: Path tracking for car-like robots based on feed-forward model predictive control[J]. Chinese Journal of Engineering. DOI: 10.13374/j.issn2095-9389.2023.10.20.001

基于前馈模型预测控制的类车机器人路径跟踪

Path tracking for car-like robots based on feed-forward model predictive control

  • 摘要: 类车机器人是一种常用于制造、仓储等领域的移动机器人。这种机器人具有相似于无人驾驶车辆的机械结构,但是也存在参考路径曲率幅度更大、系统约束范围更小、零件标准化程度更低等对路径跟踪控制具有较大影响的特点。在类车机器人路径跟踪控制方法中,模型预测控制(Model predictive control, MPC)在处理系统约束方面具有较大优势,但是现有的非线性模型预测控制(Nonlinear MPC, NMPC)实时性较差,线性模型预测控制(Linear MPC, LMPC)精确性较差,因此亟需提出一种同时具有较高精确性与实时性的类车机器人路径跟踪控制方法。为此,以无预瞄点的LMPC为基础,引入基于逆运动学模型的前馈转向角信息,提出了一种前馈模型预测控制(Feedforward MPC, FMPC)方法,并通过MATLAB和Carsim进行了联合仿真测试。FMPC具有较高的精确性,在所有仿真结果中,位移误差绝对值不超过0.0966m,航向误差绝对值不超过0.1177rad。在相同工况下,FMPC与NMPC精确性相当,LMPC、前馈控制和Stanley控制误差发散。FMPC也具有较高的实时性,在每个控制周期内的解算时间不超过4.31ms。在相同工况下,FMPC与LMPC实时性相当,相比NMPC能将每个控制周期内解算时间的最大值减小80.68%。此外,FMPC能够保证控制变量在系统约束范围内,且受定位误差的影响较小。

     

    Abstract: Car-like robots are mobile robots commonly used in manufacturing and warehousing. This kind of robot has a mechanical structure similar to that of an unmanned vehicle, but it also has characteristics that have a more significant impact on path tracking control, such as a greater magnitude of reference path curvature, a smaller range of system constraints, and a lower degree of part standardization. Among the path tracking control methods for car-like robots, model predictive control (MPC) has a tremendous advantage in dealing with system constraints. However, the existing nonlinear model predictive control (Nonlinear MPC, NMPC) has poorer real-time performance, and linear model predictive control (Linear MPC, LMPC) has poorer accuracy. So, there is an urgent need to propose a path tracking control method for car-like robots with high accuracy and real-time performance simultaneously. To this end, a feedforward MPC (FMPC) method is proposed based on LMPC without preview point and feedforward steering angle information based on the inverse kinematics model, and it is tested by joint simulation with MATLAB and Carsim. The FMPC has high accuracy, the absolute value of displacement error in all the simulation results does not exceed 0.0966m, and the absolute value of the heading error does not exceed 0.1177 rad. The accuracy of FMPC is comparable to that of NMPC under the same condition, and the errors of LMPC, feedforward control, and Stanley control are dispersed under this condition. FMPC also has a high real-time performance, and the solving time in each control period does not exceed 4.31ms. Under the same conditions, FMPC is comparable to LMPC in terms of real-time performance and can reduce the maximum value of the solving time in each control cycle by 80.68% compared to NMPC. In addition, FMPC can ensure that the control variables are within the system constraints and are less affected by positioning errors.

     

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