Speed Control Device for Automated Driving
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Solution Overview
Problem
In automated driving systems, vehicles often experience overshooting when accelerating from one target speed to another, especially when traveling uphill, due to increased traveling resistance, leading to excessive acceleration and prolonged time to reach the target speed.
Innovation Solution
A speed control device that calculates and adjusts the target speed for each road section to gradually increase over time, reducing the variation in speed and accounting for traveling resistance, using a primary delay to prevent overshooting by controlling acceleration and deceleration through a PI feedback-control method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the target speed is increased stepwise to improve acceleration efficiency, then the productivity is improved, but the actual speed abruptly increases causing overshooting
Solution Approach 1:
The patent applies dynamics by transitioning from a static stepwise target speed increase to a dynamic continuous increase model. The target speed is increased continuously at a regulated rate rather than in discrete steps, allowing the system to adapt to changing conditions and prevent overshooting while maintaining acceleration efficiency.
Solution Approach 2:
The patent changes the parameter of target speed from a stepwise discrete value to a continuously variable value that increases at a controlled rate. This parameter transformation allows for smoother speed transitions and better control stability while maintaining productivity.
2Loss of time
If the target speed is increased rapidly to improve time efficiency, then the loss of time is reduced, but the actual speed exceeds the target speed causing overshooting
Solution Approach 1:
The patent applies preliminary action by pre-regulating the rate of target speed increase before acceleration begins. By establishing a maximum rate of speed increase in advance, the system prevents overshooting from occurring while still achieving rapid acceleration, thus reducing time loss without sacrificing accuracy.
3Reliability
If the acceleration time is extended to improve speed control accuracy, then the overshooting is suppressed, but the productivity is reduced
Solution Approach 1:
The patent applies continuity of useful action by maintaining continuous acceleration at a regulated rate rather than extending acceleration time with intermittent or reduced acceleration. This allows the vehicle to reach the target speed efficiently while preventing overshooting, thus maintaining both productivity and accuracy.
4Device complexity
If the target speed is increased stepwise to simplify control, then the device complexity is reduced, but the actual speed abruptly increases causing overshooting
Solution Approach 1:
The patent applies feedback by continuously monitoring the actual speed and comparing it with the target speed, then using this information to regulate the rate of target speed increase. This feedback mechanism ensures stable speed control while maintaining relatively simple system complexity.
Data Source
AI summary
The speed control device is equipped with: an actual speed acquisition unit; an actual position acquisition unit; an acceleration/deceleration control unit; and a travel resistance calculation unit. When in a situation in which an target speed increases from a first target speed to a second target speed, the target speed in the second road section is set such that an actual speed increases with a first-order lag from the first target speed to the second target speed over a period between the start position and end position of the second road section, and the target speed in the second road section is set such that the amount of change in the speed, which increases with the first-order lag, with respect to the travel time of the vehicle is decreased as the travel resistance calculated by the travel resistance calculation unit increases.