基于预瞄曲率与状态协调的预测时域自适NMPC

Adaptive Prediction Horizon Nonlinear Model Predictive Control with Previewed Curvature Information and State Coordination

  • 摘要: 在整体式车辆稳定性轨迹跟踪控制架构的基础之上,设计了一种引入预瞄曲率信息的自适应预测时域非线性模型预测控制(NMPC). 基于预瞄的参考路径曲率点列指导控制维度变化,提升控制器对于路径曲率的动态响应能力;进一步地,引入状态协调优化机制,使控制器显示耦合至上一控制周期的车辆状态空间,有效避免预测时域变化造成的多步优化问题解耦效应,抑制因控制输入突变对轨迹跟踪控制任务的影响. 结合两种优化方法,有效改善固定预测时域策略在高曲率轨迹跟踪中因累计误差造成的跟踪精度下降问题. 最后,基于MATLAB/Simulink-CarSim联合仿真平台对算法进行了验证. 经计算,高速单移线工况下,该方法在侧向偏差均值/峰值、纵向偏差均值/峰值、航向偏差均值/峰值指标中,相较于固定预测时域NMPC同比降低36.17%/15.25%、11.55%/38.58%、6.13%/25.27%;高速双移线工况下,同比降低30.28%/29.77%、25.07%/3.85%、11.02%/2.68%. 此外,在高速低附着工况中,该方法仍能保证良好的控制精度及侧向稳定性,其峰值侧向偏差为0.2017 m、峰值纵向偏差为0.9744 km \cdot h–1、峰值航向偏差为1.1936°、峰值质心侧偏角为1.9074°.

     

    Abstract: In certain emergency maneuver scenarios, such as high-speed lane changes or collision avoidance, the trajectory-tracking controller must guarantee strict vehicle stability and maintain high control accuracy to prevent safety hazards. The strongly coupled dynamics and pronounced nonlinearities of a vehicle pose significant challenges in achieving both objectives. However, the four-wheel independently driven or steered, distributed electric-drive intelligent vehicle chassis provides a versatile platform for active safety technologies. In addition, the inherent strengths of model predictive control (MPC) in handling linear, multi-objective constraints offer theoretical support for achieving high-precision stability control. The prediction horizon determines both the step length of MPC’s receding-horizon optimization and extent of the predicted future vehicle state space, such that a longer horizon enhances control smoothness, whereas a shorter horizon improves the vehicle’s dynamic responsiveness to path-curvature variations and mitigates the control-accuracy degradation caused by accumulated model-prediction errors. To date, discussions on adaptive prediction-horizon optimization in high-speed stability MPC trajectory tracking controllers remain scarce, making it difficult to strike an optimal balance between curvature-response speed and vehicle stability. To this end, this study builds upon an integrated vehicle stability and trajectory tracking control framework, to propose an adaptive prediction horizon nonlinear model predictive control (NMPC) strategy that incorporates previewed curvature information. By leveraging a preview-based reference path curvature point sequence, the control parameters are dynamically adjusted. The proposed method enhances the controller’s responsiveness to path curvature variations and mitigates the tracking accuracy degradation caused by accumulated errors in fixed-horizon strategies during high-curvature trajectory tracking. A state-coordination optimization mechanism designed via optimization sub-objective, explicitly couples the controller to the vehicle state of the previous control cycle. This effectively suppresses the decoupling effects in multistep optimization problems induced by prediction horizon variations and minimizes the discontinuities in control inputs. Finally, the proposed algorithm was validated in a co-simulation environment built using MATLAB/Simulink and CarSim. Representative high-speed maneuvering control scenarios were selected to quantitatively assess its performance. Comparative evaluations against other methods demonstrated the superiority of the proposed algorithm: in high-speed single lane-change scenarios. The method reduced average/peak lateral deviations by 36.17%/15.25%, average/peak longitudinal deviations by 11.55%/38.58%, and average/peak heading deviations by 6.13%/25.27% compared to fixed-horizon NMPC. In high-speed double lane-change scenarios, it achieved reductions of 30.28%/29.77% (lateral), 25.07%/3.85% (longitudinal), and 11.02%/32.68% (heading). Under high-speed low-adhesion conditions (μ=0.4), the method maintained robust precision and stability with peak lateral deviation of 0.2017 m, peak longitudinal deviation of 0.9744 km/h, peak heading deviation of 1.1936°, and peak centroid sideslip angle of 1.9074°. These quantitative metrics demonstrate that adaptive predictive horizon optimization, which leverages preview curvature information and state coordination, can further improve vehicle trajectory tracking accuracy while maintaining adequate stability margins.

     

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