Manual Rotor Balancer Using IMU Inertial Sensing

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Solution Overview

Problem

Existing wheel balancers rely on expensive and calibration-prone force sensors, requiring electric energy for operation, which limits their effectiveness and accessibility, especially in environments with limited power sources.

Innovation Solution

A manual rotor balancer using inertial measurement units (IMUs) with accelerometers and gyroscopes to detect unbalances without electric energy, employing elastic elements for shaft suspension and a control unit to estimate unbalance severity and position based on signal amplitudes and phases.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If force sensors (piezoelectric sensors) are used to detect unbalances, then measurement precision is improved, but device cost increases and reliability decreases due to calibration loss

Engineering Contradiction:
Improveunbalance detection accuracyVSAvoidsensor calibration stability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the mechanical force sensing system (piezoelectric sensors) with an inertial measurement system (IMUs). Instead of measuring forces directly, the system uses accelerometers and gyroscopes to measure accelerations and angular velocities, which are then processed to determine unbalance characteristics. This substitution eliminates the calibration issues inherent in force sensors while maintaining measurement capability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses IMUs to indirectly measure unbalance forces by capturing the dynamic response of the system. Rather than directly measuring the force with a sensor that requires calibration, the system copies the effect of unbalance through inertial measurements and reconstructs the unbalance information through signal processing, avoiding the need for calibrated force sensors.

Inventive Principle:
Principle #26Copying

2Measurement precision

If piezoelectric force sensors are used for unbalance detection, then measurement precision is improved, but device cost increases

Engineering Contradiction:
Improveunbalance detection accuracyVSAvoiddevice cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent employs low-cost IMUs (accelerometers and gyroscopes) instead of expensive piezoelectric force sensors. These inertial sensors are significantly cheaper to manufacture and purchase, making the overall balancer device more cost-effective while still providing sufficient measurement precision for unbalance detection through appropriate signal processing.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent replaces the expensive mechanical force sensing approach with an inertial measurement approach using IMUs. This substitution not only reduces component cost but also simplifies the overall system architecture, eliminating the need for complex force sensor integration and calibration infrastructure.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If electric motor is used to rotate the shaft, then productivity is improved, but energy consumption increases

Engineering Contradiction:
Improvebalancing operation efficiencyVSAvoidelectric energy consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent employs a manual rotation mechanism where the user directly rotates the shaft to bring the rotor to operational speed. This self-service approach eliminates the need for an electric motor, thereby removing continuous energy consumption while still allowing the balancing operation to proceed efficiently through manual actuation followed by free rotation during measurement.

Inventive Principle:
Principle #25Self-service

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

Enables effective balancing of vehicle wheels without force sensors or electric power, providing a cost-effective and reliable solution for detecting static and dynamic unbalances using low-cost IMUs and elastic suspension, facilitating operation in energy-constrained environments.

Implementation Method 1

one or more elastic elements positioned between the shaft support and the base, such that the shaft support is elastically suspended over the base

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a first inertial measurement unit (hereinafter "IMU") fixedly positioned on the shaft support and configured to measure a first and/or a second and/or a third accelerations, and/or a first and/or a second and/or a third angular speeds

Methodology Applied
Scientific EffectInertia: Inertia

Data Source

PatentEP3943906A1Manual rotor balancer, method for manually balancing a rotor and control unit
Publication Date: 2022.01.26 ROBERT BOSCH SPA
  • EP3943906A1 patent drawingFigure 1~2
  • EP3943906A1 patent drawingFigure 3~7
  • EP3943906A1 patent drawingFigure 8~9

AI summary

A balancer (1) for balancing a rotor (5), particularly a vehicle wheel, comprises: - a base (2); - a shaft support (3) connected to the base (2); - a shaft (4) rotatable along a rotation axis (R) relative to the shaft support (3), configured such that the rotor (5) to be balanced can be mounted on the shaft (4); - means (11) for manually rotating the shaft (4); - one or more elastic elements (6) positioned between the shaft support (3) and the base (2), such that the shaft support (3) is elastically suspended over the base (2); - a first IMU (7) fixedly positioned on the shaft support (3) and configured to measure a first (az) and/or a second (ay) and/or a third accelerations (ax), and/or a first (ωz) and/or a second (ωy) and/or a third (ωx) angular speeds along three axes (x, y, z) of a reference frame integrally moving with the first IMU (7), and to generate signals representative of the same; - a second IMU (8) fixedly positioned on the shaft (4) at a radial distance from the shaft rotation axis (R), and configured to measure a first (az) and/or a second (ay) and/or a third accelerations (ax), and/or a first (ωz) and/or a second (ωy) and/or a third (ωx) angular speeds along three axes (x, y, z) of a reference frame integrally moving with the second IMU (8), and to generate signals representative of the same.