Reaction Force Output Device Friction Torque Control
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Solution Overview
Problem
The existing accelerator pedal devices experience increased reaction force due to friction torque in the motor's closed circuit, leading to insufficient motor output and poor followability of the pedal arm, especially when current conduction is restrained to avoid excessive friction.
Innovation Solution
A reaction force output device that includes a drive unit and a control unit capable of determining the space between the operated element and the drive member, adjusting the driving force output based on the presence or absence of this space, and controlling current conduction to maintain adequate driving force transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If current conduction to the motor is restrained to avoid excessive friction torque, then the reaction force from pressing operation increases more than needed, but the motor output becomes insufficient and the drive member cannot sufficiently follow the pedal arm
Solution Approach 1:
The control unit dynamically adjusts the current conduction strategy based on real-time detection of space between the drive member and operated element. When space is detected, the system switches to a mode with longer current conduction periods to increase motor output and eliminate the space. When no space is present, the system uses intermittent current conduction to reduce friction torque. This dynamic adaptation resolves the contradiction by allowing the system to optimize between friction reduction and followability maintenance based on actual operational conditions.
Solution Approach 2:
The control unit continuously monitors the space between the drive member and operated element and uses this feedback information to adjust current conduction timing and duration. This closed-loop control enables the system to detect when followability is insufficient (space present) and automatically increases motor output through extended current conduction, thereby maintaining reliable coupling between the drive member and pedal arm while managing friction torque levels.
2Reliability
If the motor generates sufficient reaction force, then the drive member can follow the pedal arm, but friction torque increases causing excessive reaction force
Solution Approach 1:
The control unit applies partial current conduction (intermittent operation) when no space is detected between the drive member and operated element, providing just enough motor output to maintain followability without generating excessive friction torque. When space is detected, the system temporarily applies excessive action (longer current conduction periods) to eliminate the space and restore proper coupling. This partial/excessive action strategy resolves the contradiction by applying motor force only when and where needed.
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 device improves followability by accurately transmitting reaction forces and enhancing the acceleration feeling by adjusting the driving force output based on the space between the elements, thereby preventing excessive reaction force and ensuring adequate motor output.
Implementation Method 1
a motor for generating a reaction force
Implementation Method 2
a return spring for returning a pedal arm to an initial position
Implementation Method 3
a lever for transmitting rotation of the motor to the pedal arm
Data Source
AI summary
A reaction force output device is provided with: a drive unit that drives a drive member to output a force in a direction opposite to an operating direction to an operated element operated by an operator; and a control unit that determines whether or not a space is formed between the operated element and the drive member, and if it is determined that the space is formed, controls the drive unit to output a greater driving force than when it is determined that the space is not formed.