Vehicle Speed Control System Low-Speed Torque Management
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Solution Overview
Problem
Existing vehicle speed control systems are ineffective in low-speed conditions and off-road terrains due to minimum speed requirements and wheel slip events, which limit their ability to maintain consistent speed without user intervention.
Innovation Solution
A vehicle speed control system that allows operation at low speeds (2-30kph) and continues to control speed even during wheel slip events by managing torque and brake application, using a combination of powertrain and braking systems to maintain a target speed value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If cruise control systems are designed to operate only above a minimum speed (15-20kph), then high-speed stability is improved, but low-speed operability deteriorates
Solution Approach 1:
The patent changes the operating parameter range of the cruise control system from traditional high-speed only (15-20kph minimum) to include low-speed operation (2-30kph range). This is achieved by modifying the control algorithms and torque management strategies to be effective at lower speeds, thereby expanding the speed parameter range where the system can adapt to different driving conditions.
2Reliability
If cruise control systems are disabled during wheel slip events, then traction control effectiveness is improved, but continuous speed control deteriorates
Solution Approach 1:
The patent merges the cruise control system with the traction control system, allowing them to operate simultaneously rather than mutually exclusively. The cruise control target speed is maintained while the traction control system manages wheel slip through torque modulation. This integration enables continuous automated speed control even during wheel slip events by coordinating both control functions.
Solution Approach 2:
The system dynamically adjusts torque demand based on real-time wheel slip detection while maintaining the cruise control target speed. The torque management strategy dynamically modulates power delivery to prevent excessive wheel spin during slip events, allowing the cruise control to remain active and provide continuous speed regulation rather than being disabled statically.
3Measurement precision
If torque demand is increased to maintain target speed, then speed control accuracy is improved, but wheel slip increases
Solution Approach 1:
The patent implements a feedback mechanism where wheel slip detection information is fed back to the torque management system. When wheel slip is detected, the system receives feedback signals and automatically modulates torque demand to reduce slip while working to maintain the target speed. This closed-loop feedback allows the system to balance speed control accuracy with slip prevention.
Solution Approach 2:
The system takes preliminary anti-action by detecting early signs of wheel slip and preemptively reducing torque demand before excessive slip occurs. The torque management strategy anticipates potential slip conditions and applies corrective torque modulation in advance, preventing the harmful effect of excessive wheel slip while maintaining speed control accuracy.
Data Source
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AI summary
PAT14-189WO1 / P300934GB B-578 SPEC 37 VEHICLE CONTROL SYSTEM AND METHOD ABSTRACT Embodiments of the present invention provide a vehicle control system comprising a speed control system, the speed control system being configured automatically to attempt to cause a vehicle to operate in accordance with a target speed value by causing a first vehicle speed value determined according to a first predetermined method to become or be maintained substantially equal to the predetermined target speed value at least in part by causing application of positive drive torque to one or more wheels by means of a powertrain, wherein the speed control system is configured to impose a constraint on the amount of driving torque that may be demanded of the powertrain in dependence on the target speed value and a second vehicle speed value determined according to a second predetermined method, said a second predetermined method being based on the mean speed of the driven wheels of the vehicle.