Pedal Force Sensor Layout for Real-Time E-Bike Assist
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Solution Overview
Problem
Existing torque sensors in electric-assisted bicycles are unable to accurately and real-time detect the force exerted by the rider's foot on the pedal, leading to inadequate real-time assistance.
Innovation Solution
A bicycle pedal design incorporating a pedal body, a force-bearing detector with a bridging frame, force-bearing beam arm, and a force sensor, such as a strain gauge, to accurately detect pedaling force and transmit it to a control module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If torque sensors are located on wheel axle or mid-mounted motor, then the system can detect torque, but the detection of actual pedaling force by rider's foot is not real-time
Solution Approach 1:
The pedal assembly is segmented into distinct functional components: the pedal body for structural support, the force-bearing detector for sensing, and the cover plate for protection. This segmentation allows the force sensor to be positioned directly at the point of force application (pedal surface), enabling real-time detection without signal lag from remote sensor locations.
Solution Approach 2:
The force-bearing beam arm acts as an intermediary mechanical element that transfers the pedaling force from the rider's foot to the force sensor. This beam arm directly transmits the applied force to the sensing element, ensuring real-time detection of actual pedaling force rather than inferred torque from wheel or motor measurements.
2Measurement precision
If speed sensors are used to detect rider movement, then the system can track speed, but the difference in pedaling force caused by changes in slope cannot be determined
Solution Approach 1:
The patent replaces speed-based sensing with direct mechanical force sensing. The force sensor (such as a strain gauge) directly measures the mechanical force applied to the pedal, providing accurate pedaling force detection that is independent of speed calculations. This allows the system to accurately detect force changes due to slope variations without relying on speed sensor data processing.
3Productivity
If existing torque sensors are used, then auxiliary power can be provided, but the detection of force exerted by rider's foot on pedal is not accurate or real-time
Solution Approach 1:
The force sensor is pre-positioned on the force-bearing beam arm, ready to immediately detect and transmit force information to the control module as soon as the rider applies force to the pedal. This preliminary positioning of the sensing element ensures that force detection begins instantly without delay, enabling reliable and real-time auxiliary power activation.
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 precise detection of pedaling force for real-time adjustment of auxiliary power, enhancing the accuracy and responsiveness of electric-assisted bicycles.
Implementation Method 1
a force sensor, such as a strain gauge, to accurately detect pedaling force
Data Source
AI summary
A bicycle pedal includes a pedal body, a force-bearing detector, and a cover plate. The pedal body has an accommodation space that is recessed. The force-bearing detector includes a bridging frame, a force-bearing beam arm, and a force sensor. A periphery of the bridging frame is fixed in the accommodation space. One end of the force-bearing beam arm is connected to the bridging frame. The force sensor is disposed on a bottom surface of the force-bearing beam arm. The cover plate is movably disposed in the accommodation space. A bottom of the cover plate is fixedly connected to a top surface of the force-bearing beam arm.