Vehicle Speed Control Logic for Low-Speed Reverse Detection Errors
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Solution Overview
Problem
Existing vehicle control systems using rotation angle sensors can erroneously determine reverse vehicle movement due to play between wheels and the driving motor, leading to incorrect speed calculations during low-speed operations.
Innovation Solution
A vehicle control apparatus that includes a motor controller, vehicle speed calculator, and vehicle speed setter, which calculates a first vehicle speed based on the rotation angle of the driving motor and sets a second vehicle speed based on the brake operation amount, setting zero speed when the brake operation exceeds a threshold and the vehicle speed falls below a certain limit, thereby preventing erroneous reverse movement detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If vehicle speed is calculated based on rotation angle of driving motor, then speed measurement is obtained, but erroneous reverse movement detection occurs due to play between wheels and motor in very low speed range
Solution Approach 1:
The patent introduces an intermediary mechanism (brake operation amount detection and threshold comparison logic) between the rotation angle sensor and the vehicle speed calculation. When the brake operation amount exceeds a threshold and the calculated speed falls below a vehicle speed threshold, the system intervenes to set speed to zero, preventing erroneous reverse movement detection caused by mechanical play in the power transmission path.
2Stability of the object's composition
If constant speed driving mode is executed in very low speed range, then speed maintenance control is achieved, but excessive torque fluctuations occur due to erroneous reverse movement detection
Solution Approach 1:
The patent applies beforehand cushioning by pre-establishing correction conditions based on brake operation amount and speed threshold before erroneous torque fluctuations occur. When these conditions are met, the system proactively corrects the vehicle speed to zero, cushioning against the potential torque fluctuations that would result from erroneous reverse movement detection during constant speed control in very low speed ranges.
3Loss of information
If rotation angle sensor output is used for speed calculation, then speed information is obtained, but play between wheels and motor causes measurement errors at low speeds
Solution Approach 1:
The patent implements feedback by continuously monitoring both the brake operation amount and the calculated vehicle speed, comparing them against predetermined thresholds. This feedback mechanism enables the system to detect when mechanical play is causing measurement errors and automatically correct the speed information by setting it to zero under appropriate conditions, thereby maintaining information accuracy despite the inherent measurement limitations of the rotation angle sensor at very low speeds.
Data Source
AI summary
A vehicle control apparatus configured to control a driving motor coupled to at least one wheel includes a motor controller, a vehicle speed calculator, and a vehicle speed setter. The motor controller controls the driving motor in a constant speed driving mode. The vehicle speed calculator calculates a first vehicle speed based on a rotation angle of the driving motor. The vehicle speed setter sets, as a driving speed in the constant speed driving mode, a second vehicle speed based on the first vehicle speed and a brake operation amount. The vehicle speed setter sets zero as the second vehicle speed when the brake operation amount exceeds its threshold and the first vehicle speed falls below its threshold, and sets the first vehicle speed as the second vehicle speed when the brake operation amount does not exceed its threshold r the first vehicle speed does not fall below its.