基于时变局部LMPC的车辆主动调速路径跟踪

Active speed adjustment path-tracking of vehicles based on time-varying local linear MPC

  • 摘要: 在矿山、港口及工业园区等需要频繁通过直角弯、U型弯和连续大曲率弯道的场景中,车辆路径跟踪控制面临精确性、实时性与行驶效率之间的矛盾. 针对这一现状,本文提出了一种基于时变局部线性模型预测控制的主动调速路径跟踪方法. 该方法通过引入时变局部坐标系,在小角度假设下对车辆动力学模型进行线性化,结合多参考点策略,提高了大曲率路径下的适应性. 为兼顾精确性与行驶效率,该方法引入基于规则的主动调速策略,根据车辆状态、路径曲率及附着极限动态调整车速,从而保证路径跟踪精确性和行驶效率,并通过MATLAB与CarSim联合仿真及硬件在环(Hardware-in-the-loop, HIL)测试验证了方法有效性. 联合仿真结果表明,所提方法能够有效完成路径跟踪,最大位移误差不超过0.1271 m. 与恒速时变局部线性模型预测控制及主动调速全局线性模型预测控制相比,误差发散得到有效抑制,精确性显著提高. 在HIL测试中,引入定位误差后的最大位移误差为0.1336 m,表明该方法具备良好鲁棒性. 在实时性方面,相较主动调速非线性模型预测控制,本文所提方法的最大计算时间和平均计算时间分别降低27.95%和25.61%,显示了较好的实时性能. 总而言之,该方法在复杂大曲率路径下实现了精确、实时且高效的路径跟踪,为工程应用提供了一种可行解决方案.

     

    Abstract: Autonomous vehicles frequently negotiate sharp turns, U-shaped curves, and continuous high-curvature paths in applications such as mining areas, ports, and industrial parks. Under such conditions, path-tracking control systems face the fundamental challenge of simultaneously ensuring tracking accuracy, real-time performance, and driving efficiency, particularly when the vehicle steering capability and computational resources are limited. Existing path-tracking methods, particularly those based on conservative constant-speed strategies, often sacrifice driving efficiency to maintain accuracy, while methods that rely on nonlinear model predictive control (NMPC) often incur excessive computational burdens in real-time applications. To address this problem, this paper proposes an active speed adjustment path-tracking control method based on time-varying local (TVL) linear model predictive control (LMPC), specifically designed for large-curvature path scenarios. The proposed method introduces a time-varying local coordinate system in which the vehicle dynamics model is reformulated and linearized under the small-angle assumption. This transformation enables the construction of a linear predictive model that remains valid over the prediction horizon, even when the vehicle traverses paths such as right-angle turns and U-shaped curves. On this basis, a multireference point strategy is incorporated into the LMPC framework, allowing the controller to explicitly account for the geometric characteristics of high-curvature paths to improve the tracking accuracy compared to conventional single-reference-point LMPC approaches. To resolve the inherent conflict among tracking accuracy, real-time performance, and driving efficiency, a rule-based active speed adjustment strategy was introduced. The strategy dynamically adjusts the vehicle speed based on the current vehicle state, path curvature, and adhesion limits to ensure that the tracking accuracy and driving efficiency are maintained. The effectiveness of the proposed TVL–LMPC-based active speed adjustment method was validated through comprehensive MATLAB–CarSim co-simulations and hardware-in-the-loop (HIL) testing. Co-simulation results demonstrate that the proposed method can stably complete path-tracking tasks at both low and high speeds on large-curvature paths, with a maximum displacement error of 0.1271 m. In contrast, the constant-speed TVL–LMPC, active speed-adjusted global LMPC, and active speed-adjusted NMPC exhibited a divergence in error when negotiating sharp turns, highlighting the superior suitability of the proposed approach for complex path scenarios. HIL tests were conducted to evaluate the performance of the proposed method under conditions similar to those in practical deployment. To assess the robustness to sensing uncertainty, random positioning errors of ±1 cm were introduced, consistent with typical positioning system performance. Under these disturbance conditions, the maximum displacement error remained below 0.1336 m, indicating that the proposed control system maintained a stable and accurate tracking performance despite localization disturbances. In terms of real-time performance, under identical simulation conditions, the proposed method reduced the maximum and average computation times by at least 27.95% and 25.61%, respectively, compared with the active speed-adjusted NMPC, confirming its suitability for real-time implementation. Overall, the proposed TVL–LMPC-based active speed adjustment path-tracking control method effectively achieves precise, real-time, and efficient path tracking on large-curvature paths. The method is particularly suited for autonomous vehicle applications in mining areas, ports, and industrial parks, where complex path geometries, real-time constraints, and operational efficiency are critical.

     

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