约束与时滞影响下的重型矿用卡车路径跟踪控制

Path tracking control of heavy mining trucks under the constraint and time delay

  • 摘要: 无人驾驶重型矿用卡车具有明显的转向机构约束和较长的信号时滞,在急弯与时滞共同作用下路径跟踪性能容易下降甚至失控。针对急弯场景中系统响应滞后造成的误差增大问题,引入参考路径未来航向并结合关键参考点位移误差构建预瞄纠偏结合控制算法(Preview-correct control, PCC),提升入弯与出弯阶段的跟踪精度。针对信号时滞导致的控制执行偏差,基于PCC输出结构与车辆控制特性建立虚拟约束处理方法,并形成多步运动补偿型时滞补偿器,用于预测时滞期间的车辆运动状态。最终将PCC与时滞补偿器整合,构建面向重型矿用卡车的路径跟踪控制系统。经过空载与满载两种工况的仿真测试与实车实验验证,所构建的控制系统在转向约束显著及时滞达0.4s的条件下均表现出较高精度和实时性。在20km/h空载仿真中,PCC的位移误差最大幅值为0.1118m,而PID(Proportional-integral-derivative)、预瞄PID等控制方法在入弯后误差发散,同时,PCC的实时性指标明显优于非线性模型预测控制(Nonlinear model predictive control, NMPC)。在满载且存在0.4s时滞的情况下,结合时滞补偿器的PCC系统将位移误差最大幅值控制在0.0949m,而未补偿的PCC与NMPC均出现误差发散。两组实车实验的位移误差最大幅值分别为0.2078m和0.1768m,车辆均能稳定通过急弯,无失控情况。结果表明,该控制系统能够在真实约束与长时滞场景下显著提升重型矿用卡车路径跟踪性能,具备工程应用与部署价值。

     

    Abstract: Heavy mining trucks are key equipment in open-pit haulage systems, where the available roadway space is often narrow in relation to the vehicle's size, resulting in high driving difficulty. With the rapid advancement of mining intelligence, autonomous-driving technology has become an essential means of improving production efficiency, ensuring operational safety, and reducing operating costs. As a core component of autonomous-driving systems, path tracking control plays a decisive role in ensuring stable vehicle motion along a reference path. However, heavy-duty mining trucks exhibit pronounced steering-mechanism constraints and significant signal transmission delays. Under the combined influence of sharp curves and long delays, the path-tracking system tends to suffer sluggish responses, rapidly increasing tracking errors, and even instability. Existing control methods struggle to simultaneously handle the compound effects of steering constraints and time delay, limiting their engineering applicability. To address the response lag caused by front-wheel steering-rate constraints in sharp-curve environments, a preview-correct control (PCC) algorithm is developed by introducing the future heading of the reference path as preview information and incorporating the key-point displacement error. The preview component improves steering proactiveness, while the correction component enhances responsiveness to current deviations, enabling stable posture adjustments during curve entry, mid-curve, and exit. PCC does not rely on complex models or high-performance computing platforms, making it suitable for real-time operation on low-power onboard controllers. To handle the widespread presence of signal transmission delay in autonomous-driving systems, a virtual-constraint treatment method is established by analyzing the PCC output structure and the characteristics of the front-wheel steering-rate constraint. On this basis, a multi-step motion–compensation delay compensator is constructed to predict the vehicle’s posture evolution during the delay interval and generate new control inputs that counteract the delay effect. By integrating PCC with the delay compensator, a path-tracking control system capable of simultaneously handling steering-mechanism constraints and long delays is achieved for heavy-duty mining trucks. Simulations were conducted under both unloaded and fully-loaded conditions, followed by full-load field experiments. In unloaded simulations at 20 km/h on a U-shaped curve with a radius of 35 m, PCC achieved a maximum displacement error of 0.1118 m, which is significantly more accurate than P-PID and PID, and close to NMPC, while its average computation time was only 0.2193 ms, far outperforming NMPC in real-time capability. Under fully-loaded conditions with a 0.4 s signal delay, PCC combined with the delay compensator maintained the maximum displacement error within 0.0949 m, whereas uncompensated PCC and NMPC both exhibited error divergence in sharp-curve sections. This demonstrates the critical role of the proposed compensation strategy in ensuring system stability under long-delay conditions. The compensator increased the average computation time by only 0.0498 ms, imposing a negligible impact on real-time performance. Two sets of full-load field tests were conducted with an actual signal delay of approximately 0.4 s, using the same U-shaped curve. The maximum displacement errors were 0.2078 m and 0.1768 m, respectively. In both tests, the vehicle navigated the sharp curve stably without loss of control or noticeable yaw deviations. Overall, simulation and experimental results demonstrate that the proposed control system can maintain stable and reliable path-tracking performance under significant steering-mechanism constraints and long signal delays, achieving a favorable balance among accuracy, real-time capability, and engineering deployability. It is therefore well-suited for practical autonomous-driving applications in heavy-duty mining trucks.

     

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