Motor Vehicle Speed Control Adaptation for Topography
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Solution Overview
Problem
Conventional cruise control systems for commercial vehicles fail to adequately account for route topography, leading to undesirable prolonged speed increases on downhill stretches, which can result in safety issues and inefficient energy use.
Innovation Solution
The method adjusts target speeds based on precalculated speed profiles using topography data, reducing the second target speed when the vehicle's speed exceeds a critical limit for an extended period, and allows for dynamic changes in the offset value between the driver's desired speed and the braking speed control, ensuring the vehicle does not exceed a predetermined speed for an extended duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the second target speed is set as a fixed offset above the first target speed, then the two control systems can work independently without interference, but the vehicle speed exceeds the driver's desired speed for prolonged periods on downhill stretches
Solution Approach 1:
The offset value between the first target speed and second target speed is changed from a fixed value to a dynamically adjustable value. The control device adjusts the offset based on monitored vehicle speed and detected downhill stretches, allowing the second target speed to adapt to route topography while maintaining independent operation of control systems
Solution Approach 2:
The system changes the parameter of the offset value from constant to variable. By monitoring vehicle speed and detecting downhill stretches longer than a threshold, the system adjusts the offset parameter to reduce the second target speed below the first target speed during prolonged descents, preventing excessive speed accumulation
2Ease of operation
If the target speed is reduced only after the vehicle speed has been above the cruise control speed for a predetermined period, then the control system responds to actual conditions, but the vehicle speed is reduced only towards the end of downhill gradients
Solution Approach 1:
The control device performs preliminary action by detecting downhill stretches before the vehicle speed exceeds the desired speed for prolonged periods. When a downhill stretch longer than a predetermined threshold is detected, the system proactively reduces the offset value and second target speed in advance, preventing excessive speed accumulation rather than reacting after the fact
Solution Approach 2:
The system dynamically adjusts the offset value based on real-time detection of downhill stretches and vehicle speed conditions. This dynamic adjustment allows the system to optimize the balance between reactive response to actual speed excess and proactive prevention of energy waste by reducing speeds at appropriate moments during the descent
3Speed
If the target speed is reduced on downhill stretches longer than a predetermined length, then prolonged speed excess is prevented, but the vehicle speed is unnecessarily reduced on routes with low gradient or intermediate valleys
Solution Approach 1:
The system applies local quality by making the offset adjustment specific to certain downhill stretches rather than applying a uniform reduction to all descents. The control device evaluates the length and characteristics of each detected downhill stretch and only adjusts the offset value when the stretch exceeds a predetermined threshold length, allowing normal speed maintenance on shorter descents and valleys
Solution Approach 2:
The system changes the offset parameter conditionally based on the detected characteristics of the downhill stretch. By monitoring the length of downhill stretches and comparing against a threshold, the system selectively adjusts the offset parameter only when necessary, maintaining high productivity on routes with low gradients or short descents while preventing speed excess on prolonged downhill sections
Data Source
Figure 1
AI summary
The invention relates to a method for adjusting at least one target speed to control the speed of a vehicle, wherein the speed control comprises a driver-requested speed control and a braking speed control. The driver-requested speed control regulates a first target speed vsoll1 via a drivetrain of the vehicle, wherein the first target speed vsoll1 is determined as a function of a selected driver-requested speed vtempopilot. The braking speed control regulates a second target speed vsoll2 via a braking device of the vehicle, wherein the second target speed vsoll2 is related to the driver-requested speed vtempopilot via an offset value Δ.The procedure further comprises the following steps: providing a topography of a route as topography data; predicting a speed profile of the vehicle depending on the topography data for a given upcoming section of the route and on a current speed (vist) of the vehicle; and reducing the second target speed vsoll2 to a value below a speed limit (vkrit) if the predicted speed profile shows that, with braking speed control using the original value of vsoll2, the vehicle speed remains continuously above the speed limit (vkrit) for longer than a predetermined exceedance time (tmax).