Steering Torque via Differential Wheel Drive
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Solution Overview
Problem
Existing steering systems for motor vehicles are complex and costly, particularly when they need to influence steering at low angles or when steering assistance is limited or fails, as they require significant mechanical and electronic components to maintain vehicle stability and maneuverability.
Innovation Solution
A method that distributes drive torque between steerable wheels to adjust their rotation, using a control system that compares the actual steering angle with a target angle, allowing for reduced energy consumption and simpler mechanical designs by generating steering torque through torque distribution, which can support or replace electromechanical drives, especially in steer-by-wire systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If superimposed steering systems are used to influence steering at low angles and maintain vehicle stability, then steering control capability is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent combines the steering function with the drive function by integrating the drive units into the steering mechanism. The drive units serve dual purposes: propelling the vehicle and providing steering torque through differential torque application to steerable wheels, thereby eliminating the need for separate superimposed steering systems
Solution Approach 2:
The drive units are designed to perform multiple functions: they act as both propulsion devices and steering actuators. By controlling the torque distribution to individual steerable wheels, the same drive units that move the vehicle forward also enable steering control, especially at low speeds and during parking maneuvers
2Ease of operation
If individual electric wheel drive motors are used to reduce turning circle at steering stop, then maneuverability is improved, but device complexity and weight increase
Solution Approach 1:
The patent merges the steering function with the drive function by integrating the drive units into the steering mechanism. The drive units serve dual purposes: propelling the vehicle and providing steering torque through differential torque application to steerable wheels, thereby eliminating the need for separate superimposed steering systems
Solution Approach 2:
The drive units automatically provide steering assistance during steering operations by detecting steering angle and speed conditions. When the vehicle is stationary or moving at low speeds with large steering angles, the drive control unit automatically applies differential torque to enable turning without additional mechanical steering assistance
3Use of energy by moving object
If torque distribution to steerable wheels is used for steering assistance, then energy consumption is reduced, but steering torque generation capability must be sufficient
Solution Approach 1:
The drive units automatically provide steering assistance during steering operations by detecting steering angle and speed conditions. When the vehicle is stationary or moving at low speeds with large steering angles, the drive control unit automatically applies differential torque to enable turning without additional mechanical steering assistance
Solution Approach 2:
The steering assistance system dynamically adjusts torque distribution based on real-time operating conditions such as vehicle speed, steering angle, and steering rate. The system provides maximum assistance when needed (low speeds, large steering angles) and reduces or eliminates assistance during normal driving conditions, optimizing both energy efficiency and steering capability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method allows for effective steering assistance with reduced energy expenditure and simpler designs, maintaining vehicle stability and maneuverability even when electromechanical drives fail, by using existing drive power to adjust wheel torques, thus providing a fallback level for steer-by-wire systems and reducing the need for additional energy or complex components.
Implementation Method 1
distribution of the drive torque as a left wheel drive torque and a right wheel drive torque to the steerable wheels in such a way that a reduction in the difference between the actual steering angle and the target steering angle
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a method for operating a steering system in an at least two-track motor vehicle having a steerable axle comprising two steerable wheels (1, 2), and having a vehicle drive (10, 11; 35), the drive torque of which can be distributed as wheel drive torques to the steerable wheels as a function of a drive controller (20), wherein the following steps are provided: • – making available a steering wheel rotational angle and an actual steering angle of at least one of the steerable wheels in the form of electronic input signals for an electronic steering control unit (23), • – evaluating the steering wheel rotational angle and calculating a setpoint steering angle on the basis of the steering wheel rotational angle, • – determining a difference in terms of absolute value and direction between the actual steering angle and the setpoint steering angle, and • – outputting a control signal from the steering control unit to the drive control unit, • – distributing the wheel drive torques as a left-hand wheel drive torque and a right-hand wheel drive torque to the steerable wheels in such a way that a reduction in the difference between the actual steering angle and the setpoint steering angle takes place.