Leaning Vehicle Gear Control for Zero-Cross Stability
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Solution Overview
Problem
The existing leaning vehicles with multi-stage automatic transmissions face challenges in maintaining controllability during turns, particularly when transitioning from a leftward lean to a rightward lean or vice versa, as the lean angle approaches zero degrees, leading to unpredictable posture changes.
Innovation Solution
The implementation of a leaning vehicle configuration that includes a lean angular velocity detector and a multi-stage automatic gear-shift controller, which adjusts the gear stages and driving force output based on the lean angular velocity and accelerator operator input, to predict and manage posture changes by holding gear stages when transitioning through zero-degree lean angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gear stages are automatically changed during turning, then the vehicle speed and acceleration are optimized, but the posture controllability deteriorates when transitioning through zero-degree lean angle
Solution Approach 1:
The gear-shift controller predicts whether the lean angle will cross zero degrees based on current lean angular velocity and acceleration, and proactively holds the gear stage before the transition occurs. This preliminary action prevents posture instability by avoiding gear changes at the critical moment when the vehicle passes through the upright position during turning.
Solution Approach 2:
The system dynamically adjusts gear-shift behavior based on real-time lean angle conditions. When the predicted lean angle indicates a transition through zero degrees, the gear stage is held constant; otherwise, normal automatic gear-shifting operates. This dynamic control strategy optimizes both vehicle performance and posture stability under varying operating conditions.
2Reliability
If the gear stages are held constant during turning, then the posture controllability is improved, but the vehicle acceleration response deteriorates
Solution Approach 1:
The gear stage is held constant only temporarily during the critical transition period when the lean angle is predicted to cross zero degrees. Once the transition is complete and the vehicle enters a stable lean state, the gear-shift controller resumes normal automatic gear-shifting operations, thereby minimizing the impact on acceleration response while maintaining posture controllability during the critical moment.
3Measurement precision
If the lean angle detection precision is increased, then the posture control accuracy is improved, but the device complexity increases
Solution Approach 1:
The gear-shift controller acts as an intermediary that uses relatively simple lean angle and lean angular velocity measurements to predict future lean angle transitions. By processing this basic sensor data through prediction algorithms, the system achieves accurate posture control without requiring complex high-precision lean angle sensors, thereby maintaining simplicity while improving control accuracy.
Data Source
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AI summary
Provided is a leaning vehicle including a multi-stage automatic transmission and that is capable of enhancing controllability of a posture during turning of the leaning vehicle while the leaning vehicle is turning in a lean state. The vehicle 1 as a leaning vehicle includes: an engine 11 configured to supply a driving force at least one of a front wheel 3 or a rear wheel 4; a gear-type multi-stage automatic transmission 12 configured to automatically change a plurality of gear stages stepwise; a lean detector 61 configured to detect a lean angular velocity of the vehicle body 2; a throttle grip 9; and a controller 7 configured to control changing of the plurality of gear stages in multi-stage automatic transmission 12 and to control an output of the engine 11 in accordance with an input operation to the throttle grip 9. The controller 7 holds the gear stages in the multi-stage automatic transmission 12 and changes the output of the engine 11 in accordance with an operation amount of the throttle grip 9, based on a vehicle state where it is predicted that the vehicle 1 changes from a leftward lean state to a rightward lean state through a state where the lean angle is zero degrees or a vehicle state where it is predicted that the leaning vehicle 1 changes from the rightward lean state to the leftward lean state through the state where the lean angle is zero degrees.