Leaning Front-Wheel Drive Control for Stable Handlebar Force

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Solution Overview

Problem

Conventional leaning vehicles struggle to maintain a constant handlebar holding force during turns regardless of speed and turning radius, and lack the ability to adjust this force according to rider preference, as well as effectively prevent tipping during high-speed maneuvers.

Innovation Solution

A leaning vehicle design with independently controllable left and right front wheels, utilizing in-wheel motors and a control system that adjusts wheel driving forces based on bank angle, vehicle speed, and rider input to manage handlebar force and prevent tipping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional leaning vehicles use a single motor or centralized drive system, then the structure is simpler, but the driving forces of left and right front wheels cannot be controlled independently

Engineering Contradiction:
ImproveIndependent control capabilityVSAvoidStructure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent divides the drive system into separate left and right in-wheel motors, allowing independent control of each wheel's driving force. This segmentation enables the system to achieve versatile control functions such as maintaining constant holding force during turns, preventing tip-overs, and adapting to different riding conditions, while the modular motor design keeps the overall structure manageable

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If the holding force is designed to be constant, then rider comfort improves, but the holding force varies with speed and turning radius making it impossible to maintain constant force

Engineering Contradiction:
ImproveHolding force consistencyVSAvoidSpeed and turning adaptation
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The control system dynamically adjusts the driving forces of left and right front wheels based on real-time vehicle speed, turning radius, and bank angle data. By continuously varying the motor output in response to changing conditions, the system maintains a constant holding force on the handlebar despite external factors like speed and turning radius variations

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system uses feedback from sensors detecting vehicle state (speed, turning angle, bank angle) and handlebar position to continuously adjust the in-wheel motor forces. This closed-loop control ensures the holding force remains constant by compensating for variations caused by different operating conditions

Inventive Principle:
Principle #23Feedback

3Productivity

If the vehicle body frame is allowed to tilt freely during turns, then turning performance improves, but the vehicle becomes unstable and may tip over during high-speed maneuvers

Engineering Contradiction:
ImproveTurning performanceVSAvoidStability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The control system proactively applies counteracting forces through the in-wheel motors before tip-over can occur. During high-speed turns, the system detects excessive bank angles and immediately adjusts the driving forces to create stabilizing moments that counteract the tipping tendency, preventing instability before it develops

Inventive Principle:
Principle #9Preliminary anti-action

Data Source

PatentEP4520642B1Leaning vehicle
Publication Date: 2026.03.11 YAMAHA MOTOR CO LTD
  • EP4520642B1 patent drawingFigure 1
  • EP4520642B1 patent drawingFigure 2
  • EP4520642B1 patent drawingFigure 3

AI summary

A leaning vehicle capable of controlling a driving force of a left front wheel and a driving force of a right front wheel independently of each other. A leaning vehicle (1) includes: a vehicle body frame (10) including a head pipe (12); a left front wheel (20L); a right front wheel (20R); a steering shaft (31) rotatable left and right together with the left front wheel (20L) and the right front wheel (20R); a handle bar (30); a link mechanism (40) that links together the vehicle body frame (10), the left front wheel (20L) and the right front wheel (20R) so that the vehicle body frame (10), the left front wheel (20L) and the right front wheel (20R) can tilt together; a left in-wheel motor (50L) provided on the left front wheel (20L); and a right in-wheel motor (50R) provided on the right front wheel (20R).