E-Bike Drive Torque Filtering for Responsive and Stable Assist
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Solution Overview
Problem
Existing electric bicycle drive units experience fluctuations in motor torque due to varying rider torque, leading to reduced ride comfort and stability.
Innovation Solution
A method involving two low-pass filters with adaptive time constants is used to smooth and control motor torque based on rider torque signals, allowing for flexible and responsive motor assistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If motor torque is controlled directly as a function of detected rider torque, then the motor support responds quickly to rider input, but torque fluctuations occur leading to reduced ride comfort
Solution Approach 1:
The patent introduces filter units as intermediary components between the rider torque detection and motor torque generation. These filters act as mediators that process the raw rider torque signal to remove fluctuations before generating motor torque, thereby decoupling the direct transmission of torque variations while maintaining responsive support.
Solution Approach 2:
The system continuously monitors the filtered rider torque signal and adjusts motor torque generation in real-time based on this feedback. The filter units process ongoing torque signals, and the motor control unit responds to the filtered feedback, creating a closed-loop system that maintains stability while responding to rider needs.
2Stability of the object's composition
If strong filtering is applied to rider torque signal, then torque fluctuations are reduced improving ride comfort, but reactivity to rider input decreases
Solution Approach 1:
The patent employs dynamic filtering where the filter characteristics are not fixed but adapt based on riding conditions. The filter units can adjust their filtering strength dynamically, allowing strong filtering during steady-state cruising for comfort while maintaining higher reactivity during acceleration or variable terrain, thus resolving the contradiction between stability and responsiveness.
Solution Approach 2:
The system changes the parameters of the filter units based on operating conditions. By adjusting filter parameters such as time constants or cutoff frequencies dynamically, the system can optimize the balance between torque smoothing and response speed for different riding scenarios, maintaining both comfort and reactivity as needed.
Data Source
AI summary
A method for operating a drive unit of an electric bicycle includes (i) determining a rider torque signal, which is based on a rider torque generated by way of muscle power of a person riding the electric bicycle, (ii) first filtering of the rider torque signal by way of a first low-pass filter, (iii) second filtering of the rider torque signal by way of a second low-pass filter, and (iv) generating, in a controlled manner, a motor torque by way of the drive unit as a function of the rider torque signal filtered by way of the second low-pass filter.