为什么需要定位轮？Why Do We Need Tracking Wheels?

想象一下：自动阶段，你让机器人前进 100cm，但轮子打滑了，实际只走了 80cm。程序以为到位了，后面所有动作全部偏移。Imagine this: during autonomous, you tell the robot to drive forward 100cm, but the wheels slip — it only actually travels 80cm. The program thinks it arrived, and every following action is off target.

核心问题：驱动轮会打滑，用驱动轮的编码器算距离不准。The core problem: drive wheels can slip, making distance calculations from drive wheel encoders inaccurate.

解决方案：装几个不连接电机的小轮子（被动轮），它们只是贴在地上滚动，不会打滑。通过它们的编码器，我们可以精确知道机器人实际走了多远。The solution: install small wheels not connected to any motor (passive wheels). They simply roll along the ground without slipping. Through their encoders, we can know exactly how far the robot actually traveled.

这就是定位轮（Tracking Wheels），也叫追踪轮、里程计轮。These are tracking wheels, also called odometry wheels.