Vehicle Drive Control Device Resolving Torque Imbalance After Braking
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Solution Overview
Problem
Conventional vehicle drive control devices experience sudden acceleration issues when the driver cancels braking, due to residual hydraulic pressure in the wheel cylinders leading to an imbalance between driving and braking torques, causing the vehicle speed to exceed target speeds.
Innovation Solution
A vehicle drive control device that includes a target driving torque control mechanism to adjust the driving torque based on feedback control, ensuring the vehicle speed deviation reaches zero, and continuously executes automatic drive control regardless of braking operations, by controlling the driving torque to be smaller than calculated during a predetermined time after braking cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the automatic drive control is executed after the driver cancels the braking operation, then the vehicle speed is controlled to reach the target speed, but the vehicle speed may exceed the target speed and the vehicle may suddenly accelerate due to residual hydraulic pressure
Solution Approach 1:
The control device determines whether the brake device is in a braking state before executing automatic drive control. By checking the braking state in advance and preventing automatic drive control when braking is detected, the system avoids the problematic condition where residual hydraulic pressure causes sudden acceleration. This preliminary check resolves the contradiction by preventing the conflicting conditions from occurring simultaneously.
Solution Approach 2:
The control device continuously monitors the braking operation state and uses this feedback to determine whether to permit automatic drive control. When braking is detected, the system feedback-loops to disable automatic drive control, thereby maintaining speed control stability and preventing sudden acceleration while still allowing normal automatic control when braking is not present.
2Speed
If the driving torque is increased to control vehicle speed to target speed after braking cancellation, then the vehicle speed reaches target speed, but the driving torque becomes excessively high causing sudden acceleration
Solution Approach 1:
The control device performs a preliminary check to determine if the brake device is in a braking state before allowing automatic drive control to increase driving torque. By detecting the braking state in advance and preventing automatic drive control execution, the system avoids generating excessively high driving torque that would cause sudden acceleration, thus resolving the contradiction between reaching target speed and controlling driving torque.
3Device complexity
If the automatic drive control is continuously executed regardless of braking operation, then the control system remains simple, but the vehicle speed control becomes unstable when residual hydraulic pressure exists
Solution Approach 1:
The control device introduces a preliminary determination step that checks whether the brake device is in a braking state before permitting automatic drive control. This simple conditional check adds minimal complexity to the control system structure while effectively preventing the instability caused by residual hydraulic pressure, thus resolving the contradiction between system simplicity and control reliability.
Data Source
AI summary
A vehicle drive control device includes a target driving torque value control means, a target braking torque value control means, and an automatic drive control means for controlling the target driving torque value control means and the target braking torque value control means through a control signal, for executing an automatic drive control by sending the control signal to the target driving torque value control means and the target braking torque value control means in order to execute a feedback control on a present vehicle speed and for continuously executing the automatic drive control, wherein the target driving torque value control means controls the target value of an actual driving torque to be smaller than an presumed target value of the driving torque calculated by presuming the target value of the braking torque to be zero, for a predetermined time after the cancellation of the braking operation.