ApolloAuto / apollo

An open autonomous driving platform
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Question about control conf #3515

Closed silverland79 closed 6 years ago

silverland79 commented 6 years ago

hi: I have some question about module of control,lincoln.pb.txt. What are the preview_window's parameters like cf,cr,mass_fl... ? Please explain the meaning of these parameters,thank you very much. lat_controller_conf { ts: 0.01 preview_window: 0 cf: 155494.663 cr: 155494.663 wheelbase: 2.85 mass_fl: 520 mass_fr: 520 mass_rl: 520 mass_rr: 520 eps: 0.01 matrix_q: 0.05 matrix_q: 0.0 matrix_q: 1.0 matrix_q: 0.0 cutoff_freq: 10 mean_filter_window_size: 10 steer_transmission_ratio: 16 steer_single_direction_max_degree: 470 max_iteration: 150 } lon_controller_conf { ts: 0.01 brake_deadzone: 15.5 throttle_deadzone: 18.0 speed_controller_input_limit: 2.0 station_error_limit: 2.0 preview_window: 20.0 standstill_acceleration: -3.0 station_pid_conf { integrator_enable: false integrator_saturation_level: 0.3 kp: 0.2 ki: 0.0 kd: 0.0 }

berthu commented 6 years ago

These are parameters for the bicycle model of lateral vehicle dynamics, a common dynamic model used for lateral vehicle control. You can learn more about it in "Vehicle Dynamics and Control" by Rajesh Rajamani. The parameters cf and cr are cornering stiffness parameter estimates for the front and rear axle tires. The mass parameters are vehicle mass estimates on each tire. They are separated in order to estimate the inertia moment of the vehicle. Preview window is a more complicated parameter; I believe it is for adjusting an overshooting problem in LQR controllers, using a technique called "Optimal Preview Control".

silverland79 commented 6 years ago

Thank you very much.