Brake Pedal Emulator With Nonlinear Counterforce and Safe Decoupling
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Solution Overview
Problem
Current braking systems in vehicles, transitioning from vacuum-based to servo-electric systems, face challenges in decoupling driver input from braking action while maintaining haptic feedback comparable to conventional systems, especially in brake-by-wire systems where the nonlinear relationship between pedal travel and force is not adequately simulated.
Innovation Solution
A pedal emulator with a rotational axis and a force generation unit that applies a nonlinear counterforce via a coupling element, featuring a reset carrier and coupling element that can be mechanically decoupled to ensure safety and maintain actuation functionality even in case of blockages, using a combination of restoring elements like return springs and intermediate springs to emulate the haptic feedback of conventional brake pedals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reset carrier and coupling element are permanently coupled, then the mechanical connection is simple and reliable, but the system cannot recover from blockages or mechanical errors
Solution Approach 1:
The permanent mechanical connection is segmented into two separable components: the reset carrier and the coupling element. These can be mechanically decoupled from each other, allowing the system to separate blocked components while maintaining overall functionality through the alternative force transmission path via the restoring element.
Solution Approach 2:
The restoring element (return spring) acts as a pre-prepared backup force generation mechanism. If the primary force generation unit fails or becomes blocked, the restoring element can still provide the necessary counterforce through the decoupled coupling element, cushioning against complete system failure.
2Productivity
If a rigid mechanical connection is used between reset carrier and coupling element, then the force transmission is direct and efficient, but the system cannot accommodate mechanical errors or blockages
Solution Approach 1:
The mechanical connection transitions from a static rigid state to a dynamic conditional state. The reset carrier and coupling element can be mechanically coupled for efficient force transmission during normal operation, but can be decoupled when errors occur, allowing the system to adapt its connectivity based on operational conditions.
Solution Approach 2:
The mechanical decoupling mechanism acts as an intermediary between the reset carrier and coupling element. It allows direct coupling for efficient force transmission when needed, but can separate them when blockages occur, mediating between the conflicting requirements of efficiency and error tolerance.
3Device complexity
If the pedal emulator uses a simple mechanical connection, then the device complexity is low, but it cannot provide the nonlinear force-displacement characteristic of conventional brake pedals
Solution Approach 1:
The force generation unit changes the physical parameters of the force-displacement relationship by implementing a nonlinear profile. Instead of a linear relationship, the counterforce increases progressively with pedal travel, replicating the haptic characteristics of conventional hydraulic brake systems through controlled parameter variation.
Solution Approach 2:
The complex hydraulic force multiplication system of conventional brakes is substituted with an electromechanical force generation unit. This unit uses electric motors and control systems to replicate the nonlinear force-displacement characteristics that were previously achieved through hydraulic mechanisms, maintaining haptic feedback quality while simplifying the overall mechanical structure.
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 pedal emulator ensures high operational reliability by simulating the nonlinear force-displacement characteristic of conventional brake pedals, providing a progressive increase in counterforce with pedal travel and enabling safe decoupling to prevent blockages, thus maintaining actuation functionality and haptic feedback in brake-by-wire systems.
Implementation Method 1
The pedal emulator has a restoring element with a reset carrier, wherein the reset carrier and the coupling element are mechanically decoupleable from one another
Data Source
AI summary
A pedal emulator for a vehicle, having a rotational axis, a pedal lever that can be rotated about the rotational axis, and a force generation unit for exerting a counterforce on the pedal lever via at least one coupling element of the force generation unit that is mechanically coupled to the pedal lever. Whereby the counterforce acts in the opposite direction to an actuation force exerted on the pedal lever. The force generation unit is designed such that a curve of the counterforce along a pedal path of the pedal lever is in the form of a non-linear curve in a pedal path-counterforce diagram.