Electric Bicycle Torque Control for Low-Speed Stability

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Solution Overview

Problem

Bicycles with electric motors experience stability issues at low speeds, requiring skilled handling, especially for older or inexperienced riders, due to increased weight and difficulty in maintaining balance during starting and stopping.

Innovation Solution

A control device that determines drive torque based on steering angle, inclination angle, and tread torque, adjusting the electric drive to enhance stability by modulating torque output, particularly at low speeds, and incorporating ABS for braking torque management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If an electric motor is added to provide drive support, then the bicycle can assist the driver, but the bicycle becomes heavier and less stable at low speeds

Engineering Contradiction:
Improvedrive supportVSAvoidstability at low speeds
Core Design Contradiction:
PowerVSStability of the object's composition

Solution Approach 1:

The control device dynamically adjusts the drive torque based on detected steering angle and inclination angle parameters. When instability is detected through sensor data, the system modifies torque output to counteract the destabilizing effects of the motor's weight, thereby maintaining stability while preserving power assist functionality.

Inventive Principle:
Principle #35Parameter changes

2Power

If the bicycle weight is increased with an electric motor, then more drive support is available, but the handling difficulty increases especially for older or inexperienced riders

Engineering Contradiction:
Improvedrive supportVSAvoidhandling ease
Core Design Contradiction:
PowerVSEase of operation

Solution Approach 1:

The system continuously monitors steering angle and inclination angle through sensors, creating a feedback loop that detects handling difficulties. When the system detects steering inputs or inclination changes indicative of struggling to maintain balance, it automatically adjusts drive torque to provide stabilizing assistance, making the heavier bicycle easier to handle for all riders.

Inventive Principle:
Principle #23Feedback

3Stability of the object's composition

If the electric drive torque is increased to improve stability, then low-speed stability improves, but the risk of excessive torque or unintended acceleration increases

Engineering Contradiction:
Improvecross-stabilityVSAvoidcontrol reliability
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The control device carefully modulates drive torque based on precise sensor measurements of steering angle and inclination angle. By making fine-grained adjustments rather than large torque changes, the system achieves cross-stability while maintaining predictable and reliable control that prevents unintended acceleration or excessive torque application.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3650326B1Bicycle with electric drive with improved stability
Publication Date: 2022.03.23 ROBERT BOSCH GMBH
  • EP3650326B1 patent drawingFigure 1~3
  • EP3650326B1 patent drawingFigure 4~5

AI summary

The present invention relates to a bicycle powered by muscle power and/or electrically, comprising an electric drive (2), a control device (3) configured to control the electric drive (2), a device (4) for determining a steering angle (α), and a device (5) for determining a tilt angle (β), wherein the control device (3) determines a drive torque for the electric drive (2) based on the steering angle (α) and the tilt angle (β).