Smart Crank Control for E-bike Motor Assistance
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Solution Overview
Problem
Conventional e-bike motor output power control systems face challenges in accurately sensing crank speed and position for Pedal Assist Systems, particularly when the electric motor assists pedaling, and existing solutions require costly and time-consuming modifications to the e-bike controller hardware and software, with torque sensors alone being insufficient for precise control.
Innovation Solution
A smart crank control system using a microcontroller, torque sensor, gyro, and accelerometer on the crank, coupled with a slip ring and pogo pin connectors to provide power and data to the e-bike controller through the throttle connector, allowing for wireless or wired communication of crank speed, position, and torque data to optimize motor assistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a torque sensor is installed on the pedal axle to sense pedaling power, then the motor can generate appropriate output power, but it becomes difficult to sense crank positions and determine rider intention
Solution Approach 1:
The patent combines multiple sensing functions (torque sensing, crank position detection, and rider intention recognition) into a single integrated smart crank assembly. The strain gauge measures torque while the crank's rotational position is simultaneously detected by the control board, allowing the system to determine both pedaling force and rider intention from one integrated sensor package rather than separate components.
Solution Approach 2:
The control board acts as an intermediary that processes signals from the strain gauge and interprets crank position data to determine rider intention. It translates raw sensor data into meaningful control commands for the motor controller, mediating between the physical crank assembly and the electronic control system.
2Ease of operation
If a wireless transmission means is used to provide torque and crank position data to the motor controller, then data can be transmitted without wires, but it requires modification of the e-bike controller hardware and software
Solution Approach 1:
The smart crank control board is designed to interface with standard e-bike controller connections, making it universally compatible with existing systems. It can output data in formats that work with both wired and wireless transmission protocols, allowing the same hardware to adapt to different communication methods without requiring controller modifications.
Solution Approach 2:
The system replaces wireless transmission hardware with a simpler wired connection through the throttle connector, eliminating the need for complex wireless receivers and signal processing. This substitution reduces device complexity while achieving the same data transmission goal.
3Force
If torque sensors are placed on the pedal axle to sense twisting power, then pedaling force can be measured, but crank positions cannot be accurately detected
Solution Approach 1:
The patent merges force sensing and position detection into a single smart crank assembly. The strain gauge measures pedaling force while the control board simultaneously detects crank rotational position, allowing both parameters to be measured from the same integrated component rather than requiring separate sensor installations.
Solution Approach 2:
The sensing function is segmented into two independent measurement capabilities within the same crank assembly: torque measurement via strain gauge and position detection via the control board's sensors. This segmentation allows each function to operate independently and accurately without interfering with the other.
4Use of energy by moving object
If a battery is added to the crank to power the smart crank system, then power can be provided to sensors and controllers, but battery life limits system use and recharging is inconvenient
Solution Approach 1:
The smart crank system is designed to be powered by the e-bike's existing battery through the throttle connector, making the system self-sufficient without requiring its own power source. The crank control board draws power during normal system operation, eliminating the need for separate battery installation and maintenance.
Solution Approach 2:
The system is designed to draw power from the e-bike's existing power infrastructure through the throttle connector, making it compatible with standard e-bike power systems. This universal power interface eliminates the need for proprietary battery solutions and leverages the existing power supply architecture.
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 safe and effective control of the assist motor by accurately determining pedaling force and intention, eliminating the need for hardware modifications and extending battery life by using existing e-bike power sources, while providing precise power assistance to the rider.
Implementation Method 1
A smart crank control system using a microcontroller, torque sensor, gyro, and accelerometer on the crank
Implementation Method 2
control board disposed on the crank and coupled to the strain gauge, the control board including gyro and accelerator motion sensors
Implementation Method 3
control board including gyro and accelerator motion sensors and a digital motion processor
Implementation Method 4
a slip ring disposed about the crank to provide for a power connection to the control board
Data Source
AI summary
The bike's crank speed and crank position are sensed via a micro controller, torque sensor, gyro and accelerator disposed on the bike's crank. External power and control signals can be passed to and from the crank micro controller and the e-bike controller through a throttle connector of the e-bike controller via slip rings around the crank hub with and with pogo pin connectors connected to the respective slip rings. Throttle data can also be provided to the e-bike controller wirelessly via a wireless dongle coupled to the throttle connector of e-bike controller.