横纵分离控制难以兼顾物理极限与精确安全边界Decoupled Control Cannot Fully Balance Physical Limits and Exact Safety Boundaries
传统方案大多采用“横纵分离”架构,例如横向 LQR/MPC 配合纵向 PID/MPC,并将上层规划下发的复杂几何走廊进行粗粒度近似。这种架构面临三重瓶颈:
- 1. 物理极限无法充分释放:大角度转向并同时加减速时,轴荷转移会改变轮胎侧向能力。横向控制器无法感知纵向驱动或制动动作,容易突破摩擦椭圆并引发打滑。
- 2. 横纵耦合导致约束匹配与跟踪失真:横纵向的动态耦合不仅会导致横向跟踪参考位置发生错位,更会导致避障点的匹配错位。这使得静态简化的避障约束(如点半空间)无法真实反映 Corridor 的真实物理边界要求,在弯道和贴边工况下近似失真,留下实际越界的碰撞风险。
- 3. 跨车型与全速域标定繁琐:分离控制高度依赖按速度分段的增益表。从低速泊车到高速巡航,再到不同车型移植,均需大量人工标定与调校。
Conventional systems separate lateral LQR/MPC from longitudinal PID/MPC and coarsely approximate complex geometric corridors. This creates three fundamental bottlenecks:
- 1. Physical limits cannot be fully exploited: When large steering angles coincide with acceleration or braking, axle-load transfer changes the lateral capability of the tires. A lateral controller that cannot sense drive or brake actions easily exceeds the friction ellipse and induces skidding.
- 2. Lateral-longitudinal coupling distorts constraint matching and tracking: Dynamic coupling between lateral and longitudinal motion misaligns not only the lateral tracking reference position but also the matching of obstacle-avoidance points. Statically simplified avoidance constraints such as point half-spaces therefore cannot represent the true physical boundary of the corridor; the approximation breaks down on curves and close to boundaries, leaving a real risk of crossing the boundary and colliding.
- 3. Tedious calibration across platforms and the full speed range: Decoupled control relies heavily on speed-segmented gain tables. From low-speed parking to high-speed cruising, and when porting to a different vehicle platform, extensive manual calibration and tuning are required.