CN-121990042-A - System and method for adjusting steering ratio while towing using steer-by-wire system

Abstract

Vehicles employ methods of towing trailers. The speedometer measures the current speed of the vehicle. The hitch length sensor obtains a current trailer length of the trailer. The steering angle sensor measures a steering wheel angle of a steering wheel of the vehicle. The processor determines a speed difference between a current speed of the vehicle and a nominal speed of the vehicle, determines a length difference between a current trailer length and a nominal trailer length, calculates a dynamic steering ratio based on the length difference and the speed difference, determines a wheel angle of the vehicle from the steering wheel angle and the dynamic steering ratio, and controls the wheel actuators to obtain the wheel angle to steer the vehicle.

Inventors

• A. Habibunejad Kolayam
• A. Gudarzi
• M. Ezzati
• S. A. nasidi
• H. Izzadi
• S. KASA yizad mahabadi

Assignees

• 通用汽车环球科技运作有限责任公司

Dates

Publication Date

20260508

Application Date

20241213

Priority Date

20241104

Claims (10)

1. 1. A method of towing a trailer behind a vehicle, comprising: measuring a current speed of the vehicle; Measuring a current trailer length of the trailer; Determining a speed difference between a current speed of the vehicle and a nominal speed of the vehicle; Determining a length difference between the current trailer length and the nominal trailer length; Calculating a dynamic steering ratio based on the length difference and the speed difference; measuring a steering wheel angle of the vehicle; determining a wheel angle of the vehicle from the steering wheel angle and the dynamic steering ratio, and The wheel actuators are controlled to obtain a wheel angle to steer the vehicle.
2. 2. The method of claim 1, further comprising determining whether a trailer is connected to the vehicle and performing one of (i) calculating a wheel angle using the dynamic steering ratio when the trailer is connected, and (ii) calculating a wheel angle using the static steering ratio when the trailer is not connected.
3. 3. The method of claim 2, further comprising steering the vehicle using the static steering ratio when at least one of (i) the vehicle is not moving in reverse, (ii) the speed of the vehicle is outside of a selected speed range, and (iii) the roll of the vehicle is outside of a selected stability range.
4. 4. The method of claim 1, further comprising determining an equation of motion for a hitch angle based on the nominal trailer length and nominal speed.
5. 5. The method of claim 1, further comprising using the dynamic steering ratio to obtain a selected hitch angle for a selected steering wheel angle of a first trailer having a first length and to obtain a selected hitch angle for a selected steering wheel angle of a second trailer having a second length.
6. 6. A system for towing a trailer behind a vehicle, comprising: A processor configured to: Obtaining a current speed of the vehicle; Obtaining a current trailer length of the trailer; Determining a speed difference between a current speed of the vehicle and a nominal speed of the vehicle; Determining a length difference between the current trailer length and the nominal trailer length; Calculating a dynamic steering ratio based on the length difference and the speed difference; obtaining a steering wheel angle of a vehicle; determining a wheel angle of the vehicle from the steering wheel angle and the dynamic steering ratio, and The wheel actuators are controlled to obtain a wheel angle to steer the vehicle.
7. 7. The system of claim 6, wherein the processor is further configured to determine whether a trailer is connected to the vehicle and to perform one of (i) calculating a wheel angle using the dynamic steering ratio when the trailer is connected, and (ii) calculating a wheel angle using a static steering ratio when the trailer is not connected.
8. 8. The system of claim 7, wherein the processor is further configured to use the static steering ratio to steer the vehicle when at least one of (i) the vehicle is not moving in reverse, (ii) the speed of the vehicle is outside of a selected speed range, and (iii) the roll of the vehicle is outside of a selected stability range.
9. 9. The system of claim 6, wherein the processor is further configured to determine an equation of motion for the hitch angle based on the nominal trailer length and nominal speed.
10. 10. The system of claim 6, wherein the processor is further configured to use the dynamic steering ratio to obtain a selected hitch angle for a selected steering wheel angle of a first trailer having a first length and to obtain a selected hitch angle for a selected steering wheel angle of a second trailer having a second length.

Description

System and method for adjusting steering ratio while towing using steer-by-wire system Technical Field The present invention relates to towing a trailer behind a vehicle, and in particular, to a system and method for dynamically adjusting the steering ratio of a vehicle steer-by-wire system to provide the same hitch angle for the same steering angle at different trailer lengths and towing speeds. Background Steering can be a very tricky operation when towing a trailer, especially when the driver is towing a trailer of different lengths in daily work. In turn, the hitch angle between the vehicle and the trailer may vary based on dynamic parameters of the trailer motion, which are affected by factors such as the trailer length and the vehicle speed. The driver needs to adjust his driving behavior to accommodate the changes in these dynamic parameters. This requires a high level of skill for the driver. It is therefore desirable to provide systems and methods for reducing or eliminating trailer behavior differences as these dynamic parameters change. Disclosure of Invention In one exemplary embodiment, a method of towing a trailer behind a vehicle is disclosed. The current speed of the vehicle is measured. The current trailer length of the trailer is measured. A speed difference between a current speed of the vehicle and a nominal speed of the vehicle is determined. A length difference between the current trailer length and the nominal trailer length is determined. A dynamic steering ratio is calculated based on the length difference and the speed difference. The steering wheel angle of the vehicle is measured. The wheel angle of the vehicle is determined from the steering wheel angle and the dynamic steering ratio. The wheel actuators are controlled to obtain a wheel angle to steer the vehicle. In addition to one or more features described herein, the method further includes calculating a dynamic steering ratio based on the wheelbase of the vehicle and a trailer distance between the hitch point and a rear axle of the trailer. In addition to one or more features described herein, the method further includes determining whether the trailer is connected to the vehicle and performing one of calculating a wheel angle using the dynamic steering ratio when the trailer is connected and calculating a wheel angle using the static steering ratio when the trailer is not connected. In addition to one or more features described herein, the method further includes steering the vehicle using the static steering ratio when at least one of the vehicle is not moving in reverse, the speed of the vehicle is outside of a selected speed range, and the roll of the vehicle is outside of a selected stability range. In addition to one or more features described herein, the method further includes determining an equation of motion for the hitch angle based on the nominal trailer length and the nominal speed. In addition to one or more features described herein, the method further includes using the dynamic steering ratio to obtain a selected hitch angle for a selected steering wheel angle of a first trailer having a first length, and obtaining a selected hitch angle for a selected steering wheel angle of a second trailer having a second length. In addition to one or more features described herein, the method further includes using the dynamic steering ratio to obtain a selected hitch angle for the selected steering wheel angle when the vehicle is moving at the first speed, to obtain a selected hitch angle for the selected steering wheel angle when the vehicle is moving at the second speed. In another exemplary embodiment, a system for towing a trailer behind a vehicle is disclosed. The processor is configured to obtain a current speed of the vehicle, obtain a current trailer length of the trailer, determine a speed difference between the current speed of the vehicle and a nominal speed of the vehicle, determine a length difference between the current trailer length and the nominal trailer length, calculate a dynamic steering ratio based on the length difference and the speed difference, obtain a steering wheel angle of the vehicle, determine a wheel angle of the vehicle from the steering wheel angle and the dynamic steering ratio, and control the wheel actuators to obtain the wheel angle to steer the vehicle. In addition to one or more features described herein, the processor is configured to calculate the dynamic steering ratio based on a wheelbase of the vehicle and a trailer distance between the hitch point and a rear axle of the trailer. In addition to one or more features described herein, the processor is configured to determine whether the trailer is connected to the vehicle and to perform one of calculating the wheel angle using the dynamic steering ratio when the trailer is connected and calculating the wheel angle using the static steering ratio when the trailer is not connected. In addition to one or more features described h