车辆动力学dynamics model
参考：https://zhuanlan.zhihu.com/p/103834150
需求是，通过RWA 获得求得轮胎侧偏角，车辆滑移角， 获得曲率 基于后轴。
beta= vehicle slip angle (vs wheelbase)
alpha_f/r = tire slip angle (tire speed vs tire central line) --后轮未画出。！
Tire speed:
Control input:
delta_f/r = tire steering angle(Road wheel angle RWA) ~ ratio ~ hand steering wheel angle(HWA)
一般车辆delta_r 不能转动=0
Measurement variables:
V= vehicle speed ≠ tire speed direction
omega =yawRate
Vehicle permanent parameters(intrinsic parameter)
heading angle (by front camera via lane marking)