Vehicle Traction Slip Control via Engine Speed Upper Limit
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Solution Overview
Problem
Existing traction control systems for vehicles face challenges in precisely implementing engine speed control to manage drive slip, often requiring complex control structures and detours through drive torque manipulation, which can lead to inefficient and unstable adhesion between wheels and the road.
Innovation Solution
The method uses an upper limit speed of the drive motor as the manipulated variable, allowing the engine speed controller to operate within the stable area of the adhesion-slip curve, eliminating the need for drive torque control and simplifying the system by leveraging existing speed controllers, with data transfer via the CAN interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If drive torque control is used as the manipulated variable for traction control, then the system can regulate wheel slip, but the control structure becomes complex and requires multiple subordinate control loops
Solution Approach 1:
The patent extracts the speed control function from the complex torque control system and uses it directly for traction control. Instead of using drive torque as the manipulated variable through multiple subordinate control loops, the invention directly utilizes the engine speed controller with upper limit speed control to regulate wheel slip, thereby simplifying the control structure while maintaining traction control effectiveness
Solution Approach 2:
The engine speed controller, which is already present in every engine control unit for other tasks, is made multi-functional by using it for traction control as well. This eliminates the need for a separate torque control system and reduces overall system complexity while maintaining the ability to regulate wheel slip
2Reliability
If target drive torque is calculated by brake control unit and transmitted to engine control unit, then wheel slip can be regulated, but the control response is delayed and implementation is imprecise
Solution Approach 1:
The patent removes the intermediate step of torque calculation and transmission between brake control unit and engine control unit. Instead, the brake control unit directly determines an upper limit speed and transmits it to the engine speed controller, which immediately executes the speed regulation, thereby reducing control response time and improving slip regulation accuracy
Solution Approach 2:
The patent introduces upper limit speed as a new intermediary variable that directly connects the brake control unit's slip regulation requirements with the engine speed controller's execution capability. This intermediary enables direct and precise control without the delays associated with torque calculation and transmission
3Device complexity
If existing speed controllers are utilized for traction control, then system complexity is reduced, but precise engine speed control for slip regulation becomes difficult
Solution Approach 1:
The patent changes the control parameter from target drive torque to upper limit speed. By transmitting upper limit speed directly to the existing engine speed controller, the invention maintains the simplicity of using existing controllers while achieving precise speed control for slip regulation, as the speed controller is inherently designed for precise speed management
Data Source
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AI summary
The invention relates to a method for controlling the traction slip of the driven wheels of a vehicle, according to which a set parameter for a drive engine (12) of the vehicle is calculated on the basis of the detected value of instantaneous wheel speed and a calculated value of set wheel velocity. According to the invention, the set parameter is formed by an upper limit value for the rotational speed of the drive engine (12).