Brake Pedal Emulator With Nonlinear Counterforce Haptics
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Solution Overview
Problem
Existing braking systems face challenges in decoupling the driver's braking command from the braking action while maintaining comparable haptics to conventional systems, particularly in the transition to brake-by-wire technology, where the force-displacement characteristic is nonlinear and requires mechanical simulation.
Innovation Solution
A pedal emulator with a rotational axis and a force generation unit that generates a nonlinear counterforce profile via a restoring element and coupling elements, including levers and springs, to emulate the haptics of a conventional brake pedal, featuring a progressive increase in counterforce with pedal travel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a brake-by-wire system with servo-electric control is used, then automation and noise reduction are improved, but haptic simulation of force-displacement characteristic deteriorates
Solution Approach 1:
A pedal emulator is introduced as an intermediary device between the driver's foot and the brake-by-wire system. The emulator includes a pedal lever rotatable about an axis, a force generation unit with restoring elements (springs) that apply counterforce, and a sensor that detects pedal position. This intermediary mechanical system provides realistic haptic feedback while the sensor transmits position data to the electronic brake control system, combining tactile realism with automated control.
2Ease of operation
If mechanical simulation of force-displacement characteristic is implemented, then haptics are improved, but device complexity increases
Solution Approach 1:
The pedal emulator is segmented into distinct functional components: a pedal lever for rotation, a force generation unit with multiple restoring elements (first and second springs) that can be independently configured, a sensor for position detection, and a housing. This segmentation allows each component to be optimized independently and simplifies assembly and maintenance while achieving the desired nonlinear force-displacement characteristic through the combined action of the springs.
3Ease of operation
If a nonlinear counterforce profile is generated, then haptic realism is improved, but manufacturing precision requirements increase
Solution Approach 1:
The nonlinear counterforce profile is achieved by using multiple restoring elements (springs) with different stiffness coefficients. By selecting springs with appropriate force constants and preloads, the system generates a realistic progressive resistance curve that mimics conventional brake pedals. The sensor provides precise position feedback that, combined with the mechanical spring characteristics, creates the desired nonlinear haptic profile without requiring extremely tight manufacturing tolerances on individual components.
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 provides a compact, structurally simple design that effectively simulates the haptics of a conventional brake pedal, allowing for a smooth and progressive braking experience in a brake-by-wire system.
Implementation Method 1
the force generation unit having a restoring element which at one end is mechanically coupled to the rotational axis, and at the other end is mechanically coupled to the coupling element via a reset carrier
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. The counterforce acting in the opposite direction to an actuation force exerted on the pedal lever. The force generation unit can be 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.