Electric Bicycle Torque Estimation via Pitch and Acceleration Sensors
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Solution Overview
Problem
Existing electric bicycles face inaccuracies in estimating rider torque due to dynamic interference accelerations, leading to inadequate electric drive performance, as they rely on complex torque sensors or insufficient pitching tendency measurements.
Innovation Solution
An electric bicycle equipped with a calculation unit that estimates rider torque by combining data from a bicycle pitch rate sensor and a vertical acceleration sensor, using a weighted model that adjusts signal weighting based on travel acceleration to accurately determine pitching tendency and account for road inclinations and air resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a torque sensor is used to determine driver torque, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent creates a virtual copy of the torque sensor function through software-based torque estimation. The calculation unit replicates torque measurement capabilities by processing data from existing sensors (acceleration sensor, speed sensor, pedal crank speed sensor) through a driving dynamics model, eliminating the need for a physical torque sensor while maintaining measurement functionality.
Solution Approach 2:
The patent replaces the mechanical torque sensor with a computational system. Instead of using a physical sensor to directly measure torque, the system uses a calculation unit that processes electrical signals from other sensors and computes torque estimates through mathematical models, substituting mechanical measurement with computational analysis.
2Device complexity
If only a vertical acceleration sensor is used to determine pitching tendency, then device complexity is reduced, but measurement precision deteriorates due to dynamic interference accelerations
Solution Approach 1:
The patent merges data from multiple sensor sources (vertical acceleration sensor, pitch rate sensor, speed sensor, pedal crank speed sensor) into a unified torque estimation process. By combining these diverse measurement inputs in the calculation unit, the system achieves accurate pitching tendency measurement that compensates for the limitations of individual sensors.
Solution Approach 2:
The calculation unit acts as an intermediary that processes and reconciles data from multiple sensors. It mediates between the raw sensor inputs and the final torque estimation, using a driving dynamics model to filter out dynamic interference accelerations and extract accurate pitching tendency information.
3Reliability
If dynamic interference accelerations are present, then reliability of torque estimation deteriorates, but adding more sensors increases device complexity
Solution Approach 1:
The system implements feedback through the driving dynamics model, which continuously processes sensor data and adjusts torque estimates based on measured parameters like acceleration, speed, and pedal crank speed. This feedback mechanism allows the system to compensate for dynamic interference accelerations and maintain reliable torque estimation without requiring additional sensors.
Solution Approach 2:
The patent changes the parameters used for torque estimation from direct torque measurement to a combination of indirectly measured parameters (acceleration, speed, pedal crank speed) processed through a dynamic model. This parameter transformation allows the system to achieve reliable torque estimation while avoiding the complexity of direct torque sensing.
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
This approach allows for reliable and accurate estimation of rider torque, ensuring proper operation of the electric drive by minimizing the impact of dynamic disturbances and improving assist torque control.
Implementation Method 1
the vertical acceleration sensor detecting the gravitational acceleration and the pitching tendency being determined by the deviation of the measured acceleration from the gravitational acceleration
Implementation Method 2
an electric motor, the electric motor being supplied with electric energy by a battery arranged on the electric bicycle
Data Source
Figure 1
Figure 2
AI summary
Electric bicycle (10) with an electric drive (20) which has a driven element (22), wherein the driven element (22) is operatively connected on the drive side to at least one electric motor (24) and on the driven side to a rear wheel (14) or a front wheel (16), wherein the magnitude of a support motor torque of the electric motor (24) depends on a rider torque acting on a pedal crank shaft (26), and a calculation unit (28) which is configured to estimate the rider torque acting on the pedal crank shaft (26), wherein a pitching tendency of the electric bicycle (10) is taken into account in the estimation of the rider torque, wherein a bicycle pitch rate sensor (30) and a bicycle vertical acceleration sensor (32) are provided, wherein the signals of the bicycle pitch rate sensor (30) and the bicycle vertical acceleration sensor (32) are used in the determination of the pitching tendency of the Electric bicycles (10) are included.This allows the driver torque to be determined reliably and with high accuracy, ensuring proper operation of the electric drive.