论文标题

安全分层模型的预测控制和自治系统计划

Safe Hierarchical Model Predictive Control and Planning for Autonomous Systems

论文作者

Koegel, Markus, Ibrahim, Mohamed, Kallies, Christian, Findeisen, Rolf

论文摘要

自动驾驶汽车的规划和控制通常是分层的。但是,提高性能需求并在高度动态的环境中运行,需要经常重新评估控制和计划的紧密整合,以确保安全。我们提出了一种集成的分层预测控制和计划方法来应对这一挑战。计划者和控制器基于移动视野最佳控制问题的重复解决方案。规划师可以选择不同的低层控制器模式以提高灵活性和性能,而不是使用具有较大安全保证金的单个控制器,以避免在不确定性下避免碰撞。计划基于简化的系统动态和安全性,但是通过基于混合智能线性编程公式的约束拧紧来确保灵活的操作。基于循环地平线的模型预测控制器可以保证对不同控制模式和干扰的限制满意度。这种模式的示例是一种慢速运动,具有高精度和快速运动,并具有较大的不确定性界限。允许不同的控制模式减少了保守主义,而问题的层次分解降低了计算成本并实现实时实现。我们得出了递归可行性的条件,以确保限制满意度和避免障碍物,以确保安全性并确保层和模式之间的兼容性。仿真结果说明了所提出的分层策略的效率和适用性。

Planning and control for autonomous vehicles usually are hierarchical separated. However, increasing performance demands and operating in highly dynamic environments requires an frequent re-evaluation of the planning and tight integration of control and planning to guarantee safety. We propose an integrated hierarchical predictive control and planning approach to tackle this challenge. Planner and controller are based on the repeated solution of moving horizon optimal control problems. The planner can choose different low-layer controller modes for increased flexibility and performance instead of using a single controller with a large safety margin for collision avoidance under uncertainty. Planning is based on simplified system dynamics and safety, yet flexible operation is ensured by constraint tightening based on a mixed-integer linear programming formulation. A cyclic horizon tube-based model predictive controller guarantees constraint satisfaction for different control modes and disturbances. Examples of such modes are a slow-speed movement with high precision and fast-speed movements with large uncertainty bounds. Allowing for different control modes reduces the conservatism, while the hierarchical decomposition of the problem reduces the computational cost and enables real-time implementation. We derive conditions for recursive feasibility to ensure constraint satisfaction and obstacle avoidance to guarantee safety and ensure compatibility between the layers and modes. Simulation results illustrate the efficiency and applicability of the proposed hierarchical strategy.

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