Vehicle Drive Force Control for Smooth Rapid Acceleration
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Solution Overview
Problem
Existing vehicle control systems fail to accurately control acceleration in response to accelerator pedal operations, leading to uncomfortable acceleration feel due to jerks and stepwise changes, especially when the pedal is operated frequently, as they do not accurately assess desired acceleration and terminate acceleration enrichment control at the wrong time.
Innovation Solution
A driving force control system that calculates a basic target acceleration based on the accelerator pedal position and vehicle speed, and adjusts it with an acceleration enrichment value when the required acceleration is high and the pedal is depressed quickly, converting this into a target driving force to enhance acceleration feel, while reducing the control gain to zero before the acceleration decreases to zero to prevent jerks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the target acceleration is corrected by multiplying with a gain greater than 1 when the accelerator pedal is depressed fast, then the desired acceleration is enhanced to achieve abrupt acceleration, but the target acceleration is reduced to an initial value when acceleration is reduced to zero, causing jerk changes and stepwise acceleration changes that make the driver feel uncomfortable
Solution Approach 1:
The patent applies dynamics by making the control gain adjustable and time-dependent. The control gain is set to a first value (greater than 1) when rapid acceleration is detected, and smoothly transitions to a second value (1) when acceleration approaches zero. This dynamic adjustment allows the system to enhance acceleration response when needed while maintaining smooth operation during cruising, resolving the contradiction between acceleration responsiveness and operational comfort.
2Device complexity
If the target acceleration is determined uniformly based on accelerator pedal position and vehicle speed, then the control system is simple to implement, but the desired acceleration cannot be assessed accurately when the accelerator pedal is depressed abruptly, leading to inaccurate acceleration control
Solution Approach 1:
The system dynamically adjusts the control gain based on the operating conditions. When the accelerator pedal is depressed rapidly (indicating abrupt acceleration demand), the control gain is increased to accurately assess the desired acceleration. When the vehicle is cruising and acceleration is near zero, the control gain returns to 1. This dynamic approach improves acceleration assessment accuracy without requiring a completely complex control architecture.
Solution Approach 2:
The patent changes the control parameter (control gain) based on operating conditions. By multiplying the target acceleration by a control gain that varies from 1 to a value greater than 1 depending on the acceleration demand, the system accurately assesses desired acceleration during abrupt pedal depression while maintaining simplicity during normal cruising conditions.
3Reliability
If the corrected target acceleration is reduced to an initial value when acceleration is reduced to zero, then the control system returns to normal operation, but the jerk of acceleration changes within the acceleration range around zero where the accelerator pedal is operated frequently, causing stepwise acceleration changes
Solution Approach 1:
The patent applies beforehand cushioning by smoothly transitioning the control gain from the first value (greater than 1) to the second value (1) before the acceleration completely reaches zero. This gradual transition cushions the change in jerk, preventing abrupt stepwise acceleration changes. The control gain is reduced to 1 when the acceleration reaches a predetermined small value, ensuring smooth operation during frequent pedal operations around the zero acceleration point.
Data Source
AI summary
A drive force control system controls acceleration of a vehicle accurately in line with an operation of an accelerator pedal to improve an acceleration feel. A controller calculates a corrected target acceleration when a required acceleration is large and an operating speed of the accelerator pedal is fast, and converts the corrected target acceleration into a target driving force to propel the vehicle so as to achieve the corrected target acceleration by generating the target driving force.