Power Steering Torque Arbitration to Prevent Position Control Oscillation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electromechanical power steering mechanisms for motor vehicles face challenges in achieving good steering feel during automatic and/or autonomous driving due to oscillations caused by parallel operation of position and torque controllers, which reduces performance and control stability.
Innovation Solution
A motor vehicle power steering mechanism with a steering controller that includes an arbitration unit, a column torque controller, and a steering algorithm, which calculates a target motor torque by weighting and adding reference steering column torques from a state feedback controller and a torque controller, eliminating the need for parallel connection of position and torque control, thereby improving steering feel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If position controller and torque controller are connected in parallel to realize position and torque control simultaneously, then both position control and torque control functions are achieved, but oscillation occurs in the closed feedback loop and controller performance is reduced
Solution Approach 1:
The patent implements dynamic switching between position control mode and torque control mode based on driver input detection. When driver torque exceeds a threshold, the system switches from position control to torque control, avoiding the oscillation problem of parallel operation while maintaining both control capabilities through temporal separation.
Solution Approach 2:
The system changes the control parameter from position (in automatic mode) to torque (in manual mode) based on operating conditions. This parameter switching resolves the contradiction by ensuring only one controller is active at a time, eliminating feedback loop oscillation while maintaining versatility through mode transitions.
2Stability of the object's composition
If both controllers are tuned weak to avoid oscillation, then control stability is improved, but steering feel and controller performance are reduced
Solution Approach 1:
By dynamically switching between control modes rather than using weakly tuned parallel controllers, the system allows each controller to be optimally tuned for its specific function. The torque controller can provide strong steering feel when needed, while the position controller maintains stability during automatic operation.
Solution Approach 2:
The system maintains continuous useful action by ensuring seamless transition between position control and torque control modes. This eliminates the need for weak tuning while preserving steering feel, as the appropriate controller is always active based on driver input conditions.
3Ease of operation
If position controller is limited to make torque controller stronger in hands-on situation, then manual steering performance is improved, but position control performance in automatic mode is reduced
Solution Approach 1:
The system dynamically allocates controller authority based on operating mode. In manual mode (hands-on), the torque controller has full authority with position control disengaged. In automatic mode (hands-off), the position controller has full authority. This dynamic allocation maximizes both manual steering performance and position control performance without mutual limitation.
Solution Approach 2:
The system changes the active control parameter from torque (manual mode) to position (automatic mode) based on driver input. This parameter change allows each control mode to operate at full performance capability without the compromises required by parallel operation or mutual limiting.
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 solution enhances steering feel and reduces oscillations by allowing series connection of the controllers, resulting in improved control stability and performance during both manual and autonomous driving modes.
Implementation Method 1
Assist force is applied to a steering mechanism by driving an electric motor
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a motor vehicle power steering mechanism with an electric motor for steering assist and/or steering, and a steering controller, which controls the electric motor with a position control mode for autonomous driving and/or automatic steering and a torque control mode for manual steering by a driver, wherein the steering controller comprises a steering column reference controller (1), an arbitration unit (6), a column torque controller (8), a steering algorithm (9), and the steering system, wherein the steering column reference controller (1) calculates for position control based on a reference position (2) and a measured position (3) a first reference steering column torque (5) and a steering algorithm (9) calculates for torque control based on a measured column torque a second reference steering column torque (10), wherein the arbitration unit (6) weights and adds the first and second reference steering column torques (9,10), and wherein the output (16) of the arbitration unit is input (16) to the column torque controller (8).