Methods and apparatus for estimating bank angle using steering-rack force

A computer-implemented method executed by data processing hardware that causes the data processing hardware to perform operations comprising:

• obtaining a measured position of a steering rack;
• determining, based on the measured position of the steering rack, an estimate of a lateral force in an axle;
• determining, using an inertial measurement unit (IMU), a measurement of the lateral force in the axle;
• determining a difference between the estimate of the lateral force in the axle and the measurement of the lateral force in the axle;
• and
• determining, based on the difference, an estimate of a bank angle of a surface.

A vehicle comprising:

• a steering rack;
• a motor configured to operate the steering rack
• an axle;
• an inertial measurement unit (IMU);
• data processing hardware;
• and
• memory hardware in communication with the data processing hardware and storing instructions that, when executed by the data processing hardware, cause the data processing hardware to perform operations comprising:
• obtaining a measured position of the steering rack;
• obtaining a measurement of a motor current of the motor;
• determining, based on the measured position of the steering rack and the measurement of the motor current, an estimate of a steering-rack force load;
• and
• determining, based on the estimate of the steering-rack force load, an estimate of a lateral force in the axle.
• obtaining, using the IMU, a lateral acceleration;
• determining, based on the lateral acceleration, a measurement of a lateral force in the axle;
• determining a difference between the estimate of the lateral force in the axle and the measurement of the lateral force in the axle;
• and
• determining, based on the difference, an estimate of a bank angle of a surface on which the vehicle is situated.