E-Bike Velocity Detection Using Pulse Timing Intervals
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Solution Overview
Problem
Existing electricity aided bicycles face instability in velocity detection, leading to discontinuous pedaling force calculations and excessive auxiliary motor power output, especially when riding uphill or on uneven ground, which can be harmful to the user.
Innovation Solution
An auxiliary power controlling method that includes a rotating speed detector and a command voltage generator, which calculates the time between pulses in the detection signal to derive an estimated velocity value and sets an electricity aid strategy table to determine the command voltage, ensuring a stable auxiliary force is provided, particularly at low movement velocities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If velocity detection is used to calculate pedaling torque force based on Newton's Second Law, then auxiliary force can be supplied, but the detection signal becomes unstable when riding uphill or on unstable ground, leading to discontinuous acceleration values and unstable pedaling force
Solution Approach 1:
The patent changes the parameter used for velocity calculation from direct acceleration measurement to time interval between pulses. By calculating velocity based on the time difference between consecutive pulses (Δt) and the known distance between pulse generation points, the system avoids direct acceleration measurement that becomes unstable on uneven terrain, thereby maintaining reliable auxiliary force supply
Solution Approach 2:
The patent replaces the mechanical/physical acceleration sensing approach with an electronic timing-based velocity calculation method. Instead of relying on acceleration sensors that produce discontinuous signals, the system uses pulse timing intervals from the driving gear rotation to derive velocity, substituting a more reliable electronic measurement approach
2Power
If velocity detection with direct acceleration calculation is used, then auxiliary motor can output auxiliary force, but calculation errors cause excessive auxiliary force that may disturb or hurt the user
Solution Approach 1:
The patent implements a feedback mechanism where the calculated velocity is continuously used to adjust the auxiliary motor output. By basing velocity calculation on stable pulse timing intervals rather than direct acceleration, the feedback loop receives more accurate input signals, preventing excessive auxiliary force generation and ensuring user safety
Solution Approach 2:
The patent preemptively prevents calculation errors by using a more robust velocity calculation method before errors can occur. By calculating velocity from pulse time intervals rather than differentiating acceleration signals, the system avoids the amplification of measurement noise and errors that would otherwise lead to harmful excessive force output
3Power
If conventional velocity detection is used, then auxiliary motor can be controlled, but the system cannot provide stable auxiliary force when movement velocity is low
Solution Approach 1:
The patent changes the calculation approach for low-velocity conditions by using pulse time interval measurement instead of acceleration-based methods. This parameter change allows the system to maintain accurate velocity measurement even when movement is slow, enabling stable auxiliary force provision at low speeds where conventional methods fail
Data Source
AI summary
An electricity aided bicycle and an auxiliary power controlling method thereof are provided. The electricity aided bicycle includes a driving circuit, a rotating speed detector and a command voltage generator. The driving circuit receives a command voltage, and drives an auxiliary motor of the electricity aided bicycle based on the command voltage. The rotating speed detector generates a detection signal having a plurality of pulses based on a rotation status of a driving gear of the electricity aided bicycle. The command voltage generator receives the detection signal, and is configured to: calculate times between two adjacent pulses in the detection signal, operate numerical value derivation operation based on the times to generate an estimated velocity value, set an electricity aid strategy table and calculate the command voltage based on the estimated velocity value and the electricity aid strategy table.