Vehicle Speed Control Torque Balancing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional vehicle speed control systems face challenges in maintaining consistent speed when navigating off-road terrain, particularly due to powertrain or engine overrun, leading to uneven vehicle composure and occupant comfort, as they struggle to adjust torque demands quickly enough to counteract changes in terrain requirements.
Innovation Solution
A speed control system that detects when a vehicle is about to overcome an obstacle and automatically applies a retarding torque to counteract powertrain overrun, using a combination of braking systems, electric machines, or gear shifts to maintain the set speed, thereby reducing fluctuations in vehicle speed and enhancing traction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional speed control systems are used for off-road terrain, then the vehicle can maintain a set speed on relatively flat surfaces, but the vehicle experiences speed fluctuations and poor composure when navigating obstacles due to powertrain overrun
Solution Approach 1:
The control system predicts upcoming torque demand changes based on terrain analysis (e.g., detecting inclines, declines, or obstacles ahead) and proactively adjusts powertrain torque before the overrun condition occurs. This preliminary action prevents speed fluctuations rather than reacting after they occur, maintaining smooth vehicle composure throughout obstacle negotiation.
Solution Approach 2:
The system continuously monitors actual vehicle speed, powertrain torque output, and terrain conditions, comparing actual speed against the commanded set speed. When deviations are detected or predicted, the controller dynamically adjusts torque demands to the powertrain in real-time, creating a closed-loop control system that maintains precise speed stability despite varying terrain requirements.
2Speed
If the powertrain torque is reduced quickly to maintain set speed after cresting an obstacle, then speed stability is improved, but the engine response lags behind torque demand changes causing overrun
Solution Approach 1:
The controller anticipates torque demand reductions based on terrain features (e.g., detecting that the vehicle is approaching a crest or decline) and begins reducing powertrain torque before the overrun condition develops. This proactive torque management accounts for the engine's inherent response lag, ensuring smooth transition through the obstacle without speed fluctuations.
Solution Approach 2:
The system dynamically adjusts the rate and magnitude of torque changes based on real-time vehicle state, terrain conditions, and powertrain operating parameters. Rather than applying fixed torque reduction schedules, the controller modulates torque demands adaptively, optimizing the balance between maintaining speed stability and respecting the engine's response characteristics across different operating conditions.
3Ease of operation
If on-highway cruise control is used at low speeds for off-road driving, then user workload is reduced and vehicle composure is enhanced, but the minimum set speed of around 30mph prevents effective use on rough terrain
Solution Approach 1:
The system fundamentally changes the speed parameter range at which cruise control operates, enabling effective control at very low speeds (including speeds below 30mph) that are appropriate for off-road terrain. The controller adapts its control algorithms and torque management strategies to maintain stability across this expanded speed range, making the system versatile for both high-speed highway driving and low-speed rough terrain navigation.
4Ease of operation
If low-speed cruise control is used for off-road driving, then user workload and vehicle composure are improved, but powertrain overrun occurs when transitioning from high-torque to low-torque environments
Solution Approach 1:
The controller implements continuous feedback monitoring of vehicle speed, powertrain torque output, and terrain conditions. When transitioning from high-torque to low-torque environments (e.g., cresting an obstacle), the system detects the changing terrain requirements and dynamically adjusts torque demands to prevent overrun, maintaining speed at the commanded set speed throughout the transition.
Solution Approach 2:
The system predicts upcoming terrain changes and proactively adjusts torque demands before the powertrain overrun occurs. By analyzing terrain features and vehicle state, the controller prepares the powertrain for upcoming torque reductions, preventing speed excursions above the set speed while maintaining smooth vehicle composure during obstacle negotiation.
Data Source
Figure 1~4
Figure 2
Figure 3
AI summary
A method for operating a speed control system of a vehicle having a plurality of wheels is provided. The method comprises receiving one or more electrical signals representative of vehicle-related information. The method further comprises determining, based on the one or more electrical signals representative of vehicle-related information, that one or more of the wheels of the vehicle have overcome an obstacle or are about to overcome an obstacle and that therefore a reduction in an applied drive torque to one or more of the wheels of the vehicle by a powertrain subsystem (applied drive torque) will be required to maintain the speed of the vehicle at a target set-speed of the speed control system. The method still further comprises automatically commanding the application of a retarding torque to one or more of the wheels of the vehicle to counteract the effect of an overrun condition in the powertrain subsystem from increasing the speed of the vehicle. A system for controlling the speed of a vehicle comprising an electronic control unit configured to perform the above- described methodology is also provided.