Force-Feedback Brake Pedal with Series Elastic Actuator
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Solution Overview
Problem
Regenerative braking in electric and hybrid vehicles disrupts the conventional brake pedal feel, leading to safety concerns and the need for re-learning by drivers due to nonlinear and unfamiliar dynamics, especially in cooperative braking systems where regenerative and frictional braking are combined.
Innovation Solution
A force-feedback brake pedal system with a pivotally mounted brake pedal, electronic circuitry communicating with both regenerative and frictional braking systems, and a series elastic actuator providing feedback through a compliant element and displacement sensors to maintain a natural brake pedal feel, ensuring robust and high-fidelity force control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If regenerative braking is applied in cooperative braking systems, then energy efficiency is improved, but brake pedal feel becomes nonlinear and unfamiliar to drivers
Solution Approach 1:
A force feedback actuator is introduced as an intermediary device between the driver's foot and the brake pedal mechanism. This actuator actively generates compensatory forces to counteract the nonlinear effects of regenerative braking, thereby preserving the conventional linear brake pedal feel that drivers expect while allowing full utilization of regenerative braking for energy efficiency.
Solution Approach 2:
The system implements a closed-loop feedback mechanism where sensors detect the actual brake pedal position and force, and this information is fed to a controller that adjusts the force feedback actuator's output in real-time. This feedback loop dynamically compensates for regenerative braking effects, maintaining consistent pedal characteristics across varying braking conditions and energy recovery states.
2Loss of energy
If regenerative braking force is increased, then energy recovery is improved, but brake pedal dynamics become abrupt and nonlinear
Solution Approach 1:
The force feedback actuator continuously monitors braking conditions and dynamically adjusts its output force to compensate for abrupt changes in regenerative braking force. This feedback control stabilizes the brake pedal dynamics by counteracting nonlinear effects, allowing high energy recovery rates while maintaining smooth and predictable pedal behavior throughout the braking range.
Solution Approach 2:
The system dynamically changes the force feedback parameter generated by the actuator based on real-time braking conditions, vehicle speed, and regenerative braking force levels. By adjusting the compensatory force parameter in response to varying operating conditions, the system maintains stable brake pedal dynamics while maximizing energy recovery across different driving scenarios.
3Device complexity
If passive elastic elements are used to provide brake pedal feel, then device complexity is reduced, but adjustability and online control capability are lost
Solution Approach 1:
The system replaces passive mechanical elastic elements with an active force feedback actuator that uses electrical control to generate braking forces. This substitution eliminates the need for complex passive elastic mechanisms while providing superior adaptability, as the actuator can be controlled electronically to adjust brake pedal characteristics in real-time based on driving conditions and driver preferences.
Solution Approach 2:
The force feedback actuator transforms the static, fixed characteristics of passive elastic elements into dynamic, adjustable parameters. The actuator can continuously modify the brake pedal force-displacement relationship online, allowing the system to adapt to different driving conditions, vehicle loads, and driver preferences, thereby providing versatility that passive mechanical systems cannot achieve.
4Measurement precision
If rigid connection between pedal and actuator is used, then force control precision is improved, but driver safety and comfort are compromised
Solution Approach 1:
The system employs a compliant interface or flexible coupling between the force feedback actuator and the brake pedal mechanism. This flexible connection allows the actuator to maintain precise force control while accommodating natural pedal deflections and vibrations, thereby preventing the transmission of harmful rigid forces to the driver's foot while preserving high force control precision for accurate braking force regulation.
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
The system effectively compensates for the disturbing effects of regenerative braking, providing a natural brake pedal feel and adjustable force feedback, enhancing driver safety and comfort by integrating regenerative and frictional braking forces, while being cost-effective and compatible with existing brake systems.
Implementation Method 1
a series elastic actuator providing feedback through a compliant element
Implementation Method 2
displacement sensors to maintain a natural brake pedal feel
Data Source
AI summary
A force-feedback brake pedal system for cooperative braking of an electric or hybrid vehicle having jointly a regenerative braking system and a frictional braking system includes a brake pedal which is pivotally mounted around a shaft or a bearing, an electronic circuitry which is in electrical communication with the regenerative braking system and the frictional braking system of the vehicle, an actuator for providing force feedback in accordance with the regenerative breaking and friction breaking of the vehicle, the actuator is in mechanical communication with the brake pedal. The force-feedback brake pedal system further includes a compliant element arranged between the brake pedal and the actuator, and a position sensor which, during operation, measuring the deflections of the compliant element and transmitting data to the electronic circuitry.