Drivetrain Kinematic State Control via End Speed Thresholding
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Solution Overview
Problem
Managing kinematic states in a vehicle's drivetrain is complex due to the need for recalculation of operating points for each motor during state changes, leading to potential overspeed issues and the risk of motors running at inappropriate operating points.
Innovation Solution
A method for controlling the drivetrain that calculates an end speed for state changes based on current and intended kinematic states, using traction forces and time increments from tabulated maps, and compares this end speed to a threshold to determine if the change is permissible, ensuring motors operate within safe parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the operating point of each motor is recalculated for each kinematic state to ensure safe operation, then the reliability of motor operation is improved, but the device complexity and computational burden increase
Solution Approach 1:
The patent pre-calculates and stores maximum speed thresholds for each kinematic state in lookup tables before operation. During runtime, the control system simply retrieves the appropriate threshold for the current kinematic state and compares the predicted end speed against it, eliminating the need for real-time recalculation of operating points and significantly reducing computational complexity while maintaining safety
Solution Approach 2:
The patent introduces a safety margin by comparing the predicted end speed with a threshold that is lower than the absolute maximum speed. This threshold acts as a cushioning buffer that prevents overspeed conditions before they can occur, accounting for the non-instantaneous nature of kinematic state changes and potential deviations in actual motor behavior
2Productivity
If the kinematic state changes are executed quickly to improve responsiveness, then the productivity of the drivetrain control is improved, but the risk of motor overspeed increases
Solution Approach 1:
Before executing a kinematic state change, the patent calculates the predicted end speed based on the current motor speed and the characteristics of the intended kinematic state. This preliminary calculation allows the system to anticipate the speed outcome and prevent overspeed conditions before they occur, enabling fast and safe state transitions
Solution Approach 2:
The patent implements a feedback mechanism where the predicted end speed is continuously compared against pre-stored maximum speed thresholds for each kinematic state. If the predicted speed exceeds the threshold, the kinematic state change is blocked or adjusted, providing real-time safety verification that enables rapid yet safe transitions
Data Source
AI summary
A method controlling a state of a drivetrain including a set of couplers and reducers between a powertrain of a motor vehicle and one or a plurality of drive wheels of the vehicle, the drivetrain configured to take up a plurality of kinematic states each defined by a diagram of engagements of the couplers and reducers making it possible to link an engine of the powertrain to at least one drive wheel, the method including: calculating, before changing the kinematic state, depending on a current speed of the vehicle, a current kinematic state of the vehicle, and an intended kinematic state that is different from the current state, a change-of-state end speed; and comparing the change-of-state end speed with a threshold.