How to identify the adaptive gear ratio for the target vehicle

[TomoyukiaW]

I plan to implement autoware to another vehicle than sample vehicle, Lexus 450h.
I understand, for speed control, we should tune accel, brake map in raw_vehicle_cmd_converter with accel_brake_map calibrator.
But for steering control, looking at pacmod_interface, it converts tire angle (AckermannControlCommand::lateral.steering_tire_angle) to steering wheel angle with adaptive gear ratio. Adaptive gear ratio is calculated in the following formula.
adaptive_gear_ratio = vgr_coef_a_ + vgr_coef_b_ * vel * vel - vgr_coef_c_ * std::fabs(steer_wheel)
How should we identify the coefficients? Should we should collect the data in various speed and steering angle and fitting the parameters? If so, there are any recommendations for the test cases, and the fitting method?

[taikitanaka3]

we identify gear ratio from rosbag data using least squared algorithm and we decide coefficient so it can be improved by using more better parameters yet we use that value for years.

[TomoyukiaW]

Thank you for your answer. I'll try it.