Rear Wheel Toe Actuator Feedback Control via Magnetic Detection
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Solution Overview
Problem
The existing rear wheel toe actuator feedback control is unstable due to axial looseness in the feed screw mechanism, leading to hunting issues when external forces are applied, especially in bad road conditions.
Innovation Solution
A rear wheel toe angle variable vehicle system that includes a rotation transmission unit with a driven gear or planetary gear deceleration mechanism, allowing for accurate detection of the rotation amount of the nut or screw shaft, enabling stable feedback control by estimating the operation amount of the rear toe actuator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a feed screw mechanism with backlash is used to achieve smooth operation of the rear toe actuator, then the ease of operation is improved, but axial looseness occurs causing instability in feedback control
Solution Approach 1:
A detection rod is introduced as an intermediary element that magnetically couples to the screw shaft. The detection rod extends axially beyond the screw shaft and interacts with a stroke sensor, allowing indirect detection of screw shaft position without physical contact that would cause backlash. This mediator transmits positional information while isolating the sensing system from mechanical looseness.
Solution Approach 2:
The patent replaces direct mechanical contact-based position detection with magnetic field-based detection. Instead of using mechanical sensors that physically contact the screw shaft (which would transmit backlash), a magnetic detection system using the detection rod and stroke sensor is employed. This substitution eliminates the transmission of mechanical looseness to the detection system.
2Measurement precision
If a stroke sensor that magnetically detects axial displacement is used, then the measurement precision is improved, but axial looseness of the feed screw causes hunting in feedback control
Solution Approach 1:
The detection rod serves as a magnetic intermediary that couples the screw shaft to the stroke sensor. It extends axially from the screw shaft and creates a magnetic field interaction zone, allowing the stroke sensor to detect positional changes without direct mechanical contact. This intermediary preserves measurement precision while isolating the system from backlash-induced hunting.
Solution Approach 2:
The patent substitutes mechanical direct-contact detection with magnetic field-based detection through the detection rod. The stroke sensor detects the position of the detection rod via magnetic field interaction, which in turn is coupled to the screw shaft position. This substitution maintains high measurement precision while eliminating the transmission of mechanical looseness to the detection system.
3Ease of operation
If backlash is provided between nut and screw shaft, then the ease of operation is improved, but the reliability of toe angle control deteriorates due to axial looseness
Solution Approach 1:
The detection rod acts as a magnetic intermediary that allows the stroke sensor to detect the position of the screw shaft without mechanical contact. This enables the feed screw to have necessary backlash for smooth operation while the detection system remains isolated from the resulting axial looseness, maintaining reliable toe angle control.
Solution Approach 2:
The patent replaces mechanical contact-based position sensing with magnetic field-based sensing through the detection rod. This substitution allows the mechanical feed screw mechanism to operate with optimal backlash for smooth operation, while the magnetic detection system accurately measures position without being affected by the mechanical looseness, thereby maintaining control reliability.
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 provides stable and accurate feedback control of the rear wheel toe angle, reducing the impact of axial looseness and external forces, thereby improving the overall stability and accuracy of the rear wheel toe angle control.
Implementation Method 1
a rotation amount detection unit (42) configured to detect a rotation amount of one of the rotation transmission unit and the nut or the screw shaft to which the rotation is transmitted by the rotation transmission unit
Data Source
AI summary
A rear-wheel toe angle variable vehicle changes a toe angle of a rear wheel by a rear toe actuator including: a housing connected to one of a rear-wheel support member and a body; a motor in the housing; a rod connected to the other of the rear-wheel support member and the body; a nut provided in one of the housing and the rod; a screw shaft provided in the other of the housing and the rod; a rotation transmission unit in the housing for transmitting rotation of the motor to the nut or screw shaft; and a rotation amount detection unit for detecting a rotation amount of one of the rotation transmission unit and the nut or screw shaft. The vehicle estimates an operation amount of the rear toe actuator based on the detected amount, and performs feedback control of the motor using the estimated amount.