Electric Motor Generator Mode for Autonomous Vehicle Braking
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Solution Overview
Problem
Existing motor vehicle brake systems are designed to be fail-safe, relying on the driver as a fallback in case of malfunctions, which is inadequate for semi-autonomous and autonomous driving scenarios where the system must remain operational until the driver re-engages.
Innovation Solution
Incorporating an electric motor that automatically switches to generator operation to generate deceleration torque and an electromechanical parking brake device, allowing the vehicle to brake autonomously and maintain control until the driver can resume control, eliminating the need for driver intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the braking system is designed to be fail-safe with driver as fallback, then the system reliability is improved for traditional driving, but the system cannot maintain autonomous operation during malfunctions in semi-autonomous driving
Solution Approach 1:
The electric motor serves dual purposes: propelling the vehicle during normal operation and autonomously braking the vehicle during malfunctions. When a braking system fault is detected, the control unit automatically switches the electric motor to generator mode, enabling self-service braking without driver intervention. This allows the system to maintain autonomous operation even when the primary braking system fails.
Solution Approach 2:
The control unit dynamically changes the operational parameters of the electric motor based on system status. During normal operation, the motor operates in motor mode for propulsion. Upon detecting a braking system malfunction, the control unit switches the motor to generator mode, fundamentally changing its operational parameter from consuming electrical energy to generating electrical energy for autonomous braking.
2Ease of operation
If the electric motor is switched to generator mode for autonomous braking, then the need for driver intervention is eliminated, but the system complexity increases
Solution Approach 1:
The electric motor is designed with multi-functionality, serving both as a propulsion device during normal operation and as an autonomous braking device during malfunctions. This universal component approach eliminates the need for separate emergency braking mechanisms, thereby reducing overall system complexity while enabling automated braking without driver intervention.
Solution Approach 2:
The invention merges the propulsion function and emergency braking function into a single integrated system using the electric motor. By combining these functions and controlling them through a unified control unit, the system avoids the complexity of separate independent systems while maintaining the capability for autonomous operation during braking system failures.
3Extent of automation
If multiple braking mechanisms are integrated for fail-operational behavior, then the autonomous braking capability is improved, but the device complexity increases
Solution Approach 1:
The control unit acts as an intermediary that manages the switching between normal braking operation and emergency autonomous braking. It monitors the braking system status and automatically activates the electric motor in generator mode when malfunctions are detected, providing intelligent coordination that enables fail-operational behavior without requiring complex mechanical linkages between multiple braking mechanisms.
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 'fail-operational' brake system behavior, ensuring the vehicle can be safely decelerated to a standstill without driver input, providing sufficient time for the driver to regain control while maintaining vehicle stability and safety.
Implementation Method 1
the at least one electric motor is switched to generator mode, in which it operates as a generator. This requires driving the electric motor, which necessitates moving its rotor
Implementation Method 2
Modern vehicles already allow for semi-autonomous driving... brake systems with hydraulically actuated brakes assigned to each wheel
Data Source
Figure 1~2
AI summary
The invention relates to a motor vehicle comprising: a number of wheels; a brake system having hydraulically actuatable brakes corresponding to each wheel; at least one brake circuit via which the brakes can be actuated; a brake booster via which the brake circuit can be operated, said brake booster being actuatable via a brake pedal to be actuated by the driver; and at least one pressure generation device and/or pressure accumulator device, which can be controlled by a control device, and via which the hydraulic pressure inside the brake circuit can be modulated. At least one electric motor (9) is provided, which motor is used in the event of a detected failure inside the brake system (2) to generate a deceleration torque by automatically switching into a generator operation, in order to brake the vehicle (1) until same has reached a standstill.