Vehicle Speed Control Adjusting Acceleration Rate by Road Gradient
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Solution Overview
Problem
Existing vehicle speed control systems cause discomfort to passengers due to inconsistent vehicle speed increase rates after low-speed running control, influenced by vehicle speed and road gradient, leading to feelings of disagreement.
Innovation Solution
A vehicle speed control system that uses a controller with a vehicle speed detector to set a variable target speed increase rate based on current vehicle speed and road gradient, ensuring the speed increase rate is adjusted dynamically to match running conditions, thereby minimizing passenger discomfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inhibition of gear positions is cancelled according to a fixed pattern based on gear position and elapsed time, then the vehicle speed can be prevented from rapidly increasing, but the rate of speed increase may cause passenger discomfort depending on running conditions
Solution Approach 1:
The patent applies dynamics by making the speed increase rate variable rather than fixed. The controller dynamically adjusts the speed increase rate based on detected vehicle speed, ensuring that the rate adapts to current running conditions. This resolves the contradiction by maintaining reliable speed control while improving passenger comfort through condition-dependent adjustment.
Solution Approach 2:
The patent changes the parameter of speed increase rate from a fixed value to a variable value that depends on vehicle speed. By setting the speed increase rate as a function of current speed (higher at high speeds, lower at low speeds), the system maintains control reliability while adapting to different operating conditions to prevent passenger discomfort.
2Device complexity
If a fixed speed increase rate is used after vehicle speed limit control, then the control system is simple to implement, but passengers may feel disagreement about the speed increase under varying running conditions
Solution Approach 1:
The patent changes the speed increase rate parameter from constant to variable based on vehicle speed. The controller sets different speed increase rates according to the detected vehicle speed, making the rate higher when vehicle speed is high and lower when vehicle speed is low. This maintains reasonable system complexity while significantly improving passenger comfort.
3Productivity
If the vehicle speed increases at the same rate regardless of current speed, then the control logic is simple, but the passenger perceives different comfort levels at different speed ranges
Solution Approach 1:
The patent implements parameter changes by making the speed increase rate dependent on current vehicle speed. The controller adjusts the rate dynamically - using a higher rate when vehicle speed is high and a lower rate when vehicle speed is low. This maintains efficient control processing while ensuring consistent passenger comfort across different speed ranges.
Data Source
AI summary
If a condition for finishing speed limit control is satisfied, a gradient of a slope of the road is estimated based on a steady component of the longitudinal acceleration of the vehicle, and a correction factor is computed based on the slope gradient of the road, while a target acceleration of the vehicle is computed based on the vehicle speed. Then, a target vehicle speed is computed by adding the target vehicle speed of the last cycle to the product of the correction factor, target acceleration and the cycle time of the control, and the braking or driving force of each wheel is controlled so that the vehicle speed becomes equal to the target vehicle speed. In this manner, a passenger of the vehicle is prevented from feeling uncomfortable about the speed increase after the completion of the vehicle speed limit control.