Bicycle Automatic Transmission Control Device for Shifting Optimization
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Solution Overview
Problem
Manual shifting in bicycles can be difficult for riders due to the need for proper force, timing, and direction, leading to inefficient gear ratios and pedaling inefficiency, while existing automatic drivetrains only consider cadence without accounting for other resistances affecting pedaling efficiency.
Innovation Solution
A control device for an automatic transmission that adjusts cadence ranges based on detected traveling resistance, using sensors to compute torque, crankshaft rotations, and bicycle speed, and switches between shift modes to optimize gear selection and reduce jarring shifts during high torque input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual shifting controls are used, then the rider can change gear ratios, but the shifting operation becomes difficult to master and may not be timely or properly executed
Solution Approach 1:
The system enables automatic shifting by allowing the drivetrain to self-adjust gear ratios based on detected cadence and calculated traveling resistance, eliminating the need for manual rider intervention while maintaining reliable and timely shifting execution
Solution Approach 2:
The controller continuously monitors cadence sensor data and calculates traveling resistance based on torque, crankshaft rotation speed, and bicycle speed feedback, using this information to automatically determine optimal speed stages and execute shifting operations without manual input
2Ease of operation
If automatic drivetrains consider only cadence for speed stage selection, then the system is simple to operate, but other resistances affecting pedaling efficiency are not accounted for
Solution Approach 1:
The system expands the control parameters from cadence alone to include calculated traveling resistance derived from torque, crankshaft rotation speed, and bicycle speed, enabling more accurate speed stage selection that accounts for rolling resistance, drivetrain resistance, gravitational force, and other resistive factors
Solution Approach 2:
The controller replaces simple cadence-based mechanical shifting logic with a computational system that calculates traveling resistance using sensor data and applies this information to optimize speed stage selection for improved pedaling efficiency
3Productivity
If cadence ranges are adjusted based on traveling resistance, then pedaling efficiency improves and jarring shifts are avoided, but the control system becomes more complex
Solution Approach 1:
The system dynamically adjusts cadence ranges for each speed stage based on calculated traveling resistance, allowing the control parameters to adapt in real-time to changing resistance conditions while maintaining a manageable control structure through systematic adjustment rules
Data Source
AI summary
A control device for an automatic transmission for a bicycle is provided. The control device comprises a controller configured to instruct the automatic transmission to shift among a plurality of speed stages, each speed stage having an associated cadence range, wherein the controller is further configured to determine a traveling resistance of the bicycle, and if the traveling resistance exceeds a predetermined threshold, the controller is configured to adjust at least one of the cadence ranges, and following the adjustment of the at least one cadence range, the controller is further configured to operate the automatic transmission to shift based upon the adjusted cadence range and a detected cadence.