Coaxial Direct-Drive Steering Override for Autonomous Vehicle Testing
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Solution Overview
Problem
Existing steering systems for autonomous vehicles do not adequately allow for user intervention in unexpected or dangerous situations, and lack safe disengagement mechanisms, leading to potential accidents and unsafe testing conditions.
Innovation Solution
A steering system with a direct drive motor coaxially attached to the steering axle, allowing manual override and disengagement based on predefined states and limits, using a controller assembly to monitor and control vehicle conditions for safe intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a geared motor system is used to assist steering, then steering torque can be reduced to assist the operator, but additional moving components are introduced that are prone to wear and failure
Solution Approach 1:
The patent removes the gear transmission components from the steering system, using a direct-drive motor configuration where the motor shaft is directly connected to the steering wheel. This extraction of unnecessary mechanical components eliminates wear points and failure modes associated with gears, belts, and couplings while maintaining the torque assistance function.
Solution Approach 2:
The patent replaces the mechanical gear-based torque multiplication system with an electrical control system that directly drives the steering wheel. The motor controller electronically manages torque delivery, substituting complex mechanical transmissions with a simpler electro-mechanical direct-drive architecture that improves reliability.
2Ease of operation
If the motor is calibrated to allow easy override by the user, then manual intervention is possible, but excessive torque may be generated during normal operation
Solution Approach 1:
The patent implements dynamic torque calibration where the motor's torque output is continuously adjusted based on real-time detection of user steering inputs. The system monitors steering wheel position, speed, and torque sensor data to dynamically modulate motor assistance, allowing easy manual override when the user applies force while preventing excessive torque during autonomous operation.
Solution Approach 2:
The patent uses feedback from torque sensors and position sensors to continuously monitor steering wheel conditions and adjust motor torque output accordingly. When a user intervention is detected through torque threshold exceedance or rapid position changes, the feedback loop reduces or disables motor torque, enabling safe manual override while maintaining controlled torque levels during normal operation.
3Measurement precision
If autonomous steering control is implemented without disengagement limits, then automated driving precision is improved, but the driver cannot take over control when necessary
Solution Approach 1:
The patent pre-configures disengagement limits and safety thresholds before operation begins. These predetermined limits on steering torque, angular velocity, and position deviations are set to prevent the autonomous system from executing dangerous maneuvers. When these pre-set limits are approached, the system proactively disengages or alerts the driver, preventing loss of control while maintaining precise autonomous operation within safe boundaries.
4Device complexity
If a direct drive motor is used with coaxial alignment, then the number of moving parts is reduced and inertia is minimized, but precise alignment and mounting complexity increases
Solution Approach 1:
The patent merges the motor shaft axis with the steering wheel axis into a single coaxial alignment, eliminating separate transmission shafts, gears, and coupling components. The motor is directly mounted to the steering column with its rotation axis aligned to the steering wheel, combining multiple functional elements into one integrated assembly that reduces part count while requiring precise mounting.
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
Enables safe testing of autonomous vehicles in various driving scenarios by ensuring driver intervention when necessary, improving safety and reliability through reduced inertia, fewer moving parts, and enhanced control precision.
Implementation Method 1
a direct drive motor (25) controllably affecting a torque on the steering axle (20), wherein the direct drive motor (25) has an axis of rotation being coaxial with the steering axle (20)
Data Source
AI summary
The invention is a steering system for use in test driving of an autonomous vehicle, comprising—a manual steering means configured to manually steer the vehicle, —a steering axle (30) attached to the manual steering means, and—a direct drive motor (35) controllably affecting a torque on the steering axle (30), wherein the direct drive motor (35) has an axis (37) of rotation being coaxial with the steering axle (30). The steering system is characterized in that—it has at least two predefined states characterizing different driving conditions, wherein each predefined state has at least one predefined disengagement limit, and—it further comprises a controller assembly operable based on a control parameter, the controller assembly being configured to detect an actual predefined state of the vehicle, and the controller assembly initiates a disengagement of the direct drive motor (35) if, based on a difference value between a prescribed value of the control parameter and an actual value of the control parameter, the at least one predefined disengagement limit corresponding to the actual predefined state is reached. The invention further relates to a disengagement method, and a data processing system, a computer program product and a computer readable medium carrying out the method.