Vehicle Speed Control Torque Filtering for Off-Road Slip
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vehicle speed control systems are ineffective at low speeds and in off-road conditions, often disabling due to minimum speed requirements or wheel slip events, leading to reduced driver confidence and vehicle responsiveness.
Innovation Solution
A control system that receives a target speed input, determines a target speed torque parameter, and adjusts a filter torque parameter based on the difference between current and target speeds, allowing the powertrain to develop torque corresponding to the filtered parameter, enhancing responsiveness and driver confidence by simulating accelerator pedal release for smoother speed control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a minimum speed requirement is imposed on cruise control systems to reduce low speed collision risk, then safety is improved, but the system becomes ineffective in low speed and off-road conditions
Solution Approach 1:
The system dynamically adapts its operational characteristics based on detected driving conditions. When off-road or low-speed conditions are detected, the system modifies its torque control parameters and filtering behavior to remain effective, rather than being disabled by a fixed minimum speed threshold. This allows the system to maintain adaptability across diverse operating conditions while preserving safety through context-aware control adjustments.
2Reliability
If the cruise control system is disabled upon detecting wheel slip events, then collision risk is reduced, but the system cannot maintain vehicle progress in off-road conditions where wheel slip is common
Solution Approach 1:
The system applies different control strategies to different wheels based on individual wheel slip detection. Rather than disabling the entire system upon detecting slip in one wheel, the controller modifies torque distribution and control parameters locally for affected wheels while maintaining overall speed control functionality. This allows the system to handle wheel slip events in off-road conditions without completely disabling progress maintenance.
Solution Approach 2:
The system continuously monitors wheel slip events and uses this feedback to dynamically adjust control parameters. When wheel slip is detected, the system modifies torque requests and filtering behavior in real-time to accommodate the slip condition while maintaining speed control objectives. This feedback mechanism allows the system to remain effective in off-road conditions where wheel slip is common, rather than being disabled.
3Speed
If the system commands high torque to reach target speed quickly, then responsiveness is improved, but transitions become abrupt and reduce driver confidence
Solution Approach 1:
The system uses filtering with adjustable time constants to progressively adjust torque commands rather than applying full torque immediately. This creates a controlled, periodic adjustment of powertrain torque that maintains responsiveness while avoiding abrupt transitions. The filter time constant can be adjusted based on driving conditions to balance responsiveness and smoothness, preserving driver confidence.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a control system and method for a vehicle operable to implement a speed control function (12; LSP). The user sets a target speed at wich the vehicle shall travel. A target speed torque determining means (12; LSP) for determines an instantaneous value of torque, target speed torque (LSP_ tq _rq), that should be applied to one or more wheels of the vehicle by a powertrain in order to control the vehicle to travel at the target speed. Said target speed torque (LSP_tq_rq), is supplied to a modifier means (320) which modifies the target speed torque (LSP_tq_rq), considering acual and set vehicle speed (v_actual, v set, providing a modified torque request (Mod tq). Said modified signal is subsequently filtered. The system and method may, in addition, include direct input from a driver (pedal tq_rq) and a maxmimum selector (315).