E-Bike Motor Control for Speed Sensor Tamper Detection

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Solution Overview

Problem

Conventional abnormality detection techniques in electric motor-assisted bicycles fail to reliably detect unauthorized alterations that manipulate vehicle speed or torque sensors, which can remove differentiated upper limits for assist force set for different speed ranges, leading to complex configurations and inaccurate detection.

Innovation Solution

A simple configuration using a vehicle speed sensor, torque sensor, motor controller, threshold determiner, and unauthorized alteration detector to compare the running output (sum of assist force and pedal force) with a vehicle speed-dependent unauthorized alteration determination threshold, enabling detection of unauthorized alterations and subsequent control actions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional abnormality detection techniques are used to monitor motor control, then some abnormality detection capability is provided, but unauthorized alterations manipulating vehicle speed or torque sensors cannot be reliably detected

Engineering Contradiction:

Improveabnormality detection reliabilityVSAvoidunauthorized alteration detection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The system continuously compares the actual vehicle speed and torque sensor outputs against expected values calculated from motor control parameters. This feedback mechanism detects discrepancies indicating unauthorized alterations, such as when sensor outputs do not match the relationship between motor assist force and pedal force at the detected vehicle speed.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The control apparatus acts as an intermediary that validates sensor data against pre-stored correspondence data between vehicle speed and allowable assist force ratios. This intermediary validation layer identifies unauthorized alterations without requiring direct modification of the sensor hardware themselves.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If sensors are altered to manipulate vehicle speed or torque information, then differentiated upper limits for assist force are removed, but detection of such alterations becomes more difficult

Engineering Contradiction:

Improveassist force control flexibilityVSAvoidsensor alteration detection difficulty

Core Design Contradiction:

Adaptability or versatilityVSDifficulty of detecting and measuring

Solution Approach 1:

The system pre-stores correspondence data defining the relationship between vehicle speed and allowable assist force ratios before operation. During operation, actual sensor outputs are compared against these pre-established criteria, enabling detection of unauthorized alterations that attempt to remove speed-based assist force limitations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system monitors changes in the relationship between vehicle speed, torque sensor output, and motor assist force. When unauthorized alterations change these parameters beyond acceptable ranges defined by the pre-stored correspondence data, the system detects the alteration through parameter deviation analysis.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If multiple sensors for different rotating bodies are used to detect alterations, then detection capability is improved, but device complexity increases

Engineering Contradiction:

Improvesensor alteration detection reliabilityVSAvoiddetermination arrangement complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The control apparatus performs multiple functions using the existing vehicle speed sensor and torque sensor: it controls motor assist force based on detected vehicle speed, monitors the relationship between sensor outputs and pre-stored correspondence data, and detects unauthorized alterations. This multi-functional approach eliminates the need for additional dedicated detection sensors.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The control apparatus uses its own existing sensor inputs (vehicle speed sensor and torque sensor) to detect unauthorized alterations. Rather than requiring separate detection sensors, the system self-monitors its own operational parameters and identifies alterations through analysis of the relationships between parameters it already measures.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS11851133B2Electric motor-assisted bicycle and motor control apparatus

Publication Date: 2023.12.26 YAMAHA MOTOR CO LTD

AI summary

An electric motor-assisted bicycle includes a vehicle speed sensor to detect a vehicle speed, a torque sensor to detect a pedal force on a pedal connected to a crankshaft, a motor to generate an assist force that assists the pedal force, a motor controller to control the assist force by the motor depending on the pedal force and the vehicle speed, a threshold determiner to determine an unauthorized alteration determination threshold depending on the vehicle speed, and an unauthorized alteration detector to determine whether an unauthorized alteration has been made to the vehicle speed sensor or the torque sensor by comparing a running output and the unauthorized alteration determination threshold, wherein the running output is the sum of the assist force by the motor and the pedal force. If an unauthorized alteration has been made, a predetermined control is performed to address the unauthorized alteration.