Electronic Throttle Valve Control with Feed Forward Compensation
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Solution Overview
Problem
Electronic throttle valve systems face challenges in accurately controlling throttle valve position due to varying spring forces and gear train backlash, leading to delayed responses and hysteresis near the limp home position, which existing feedback-only control systems struggle to overcome effectively.
Innovation Solution
A method and system that utilize feed forward signals to actuate the throttle valve, combining a velocity feed forward signal based on position change rate and a position feed forward signal based on comparison to the limp home position, along with feedback control, to overcome backlash and spring force variations, ensuring precise throttle valve positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring is used to force the throttle blade to a nominal high-idle condition in case of loss of control, then the throttle valve can return to a safe position, but the spring requires the throttle valve actuator to apply varying force to overcome the spring constant, increasing actuator complexity and reducing response accuracy
Solution Approach 1:
The control system pre-determines the limp home position and calculates feed forward signals that anticipate the spring force requirements. By preparing the actuator with pre-calculated force commands based on desired position and rate of change, the system eliminates the need for the actuator to reactively overcome spring forces, thereby reducing actuator complexity while maintaining the safety function.
Solution Approach 2:
The system implements a feedback controller that continuously monitors the actual throttle valve position and adjusts the actuator output to match the desired position. This closed-loop feedback compensates for the varying spring forces, allowing the actuator to maintain precise control without requiring complex force management logic.
2Power
If a gear train is used to connect the motor to the throttle valve, then mechanical advantage is achieved, but backlash in the gear train causes delay in response and hysteresis, reducing positioning accuracy
Solution Approach 1:
The control system calculates a feed forward signal that anticipates the backlash effect by considering the rate of change of throttle valve position. When the throttle valve needs to reverse direction or move from a stationary position, the feed forward signal pre-compensates for the expected backlash delay, allowing the system to maintain positioning accuracy despite the mechanical play in the gear train.
Solution Approach 2:
The feedback controller continuously monitors the actual throttle valve position and generates correction signals to compensate for backlash-induced positioning errors. By comparing the desired position with the actual position and adjusting the motor output accordingly, the system eliminates the impact of gear train backlash on final positioning accuracy.
3Device complexity
If feedback-only control is used to control the throttle valve position, then the system is simple to implement, but the system struggles to overcome backlash and spring force variations, leading to delayed responses near the limp home position
Solution Approach 1:
The system introduces a feed forward control component that pre-calculates the actuator command based on the desired throttle valve position and its rate of change. This preliminary action anticipates the required force to overcome spring forces and backlash effects before they occur, significantly improving response speed near the limp home position without adding complex control logic.
Solution Approach 2:
The system combines feed forward control with feedback control in a unified control strategy. The feed forward component provides anticipatory control to overcome inertia, spring forces, and backlash, while the feedback component ensures accurate position tracking. This merged approach maintains relative simplicity while dramatically improving response performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables faster and more robust control of the throttle valve position, reducing delays and hysteresis issues by compensating for backlash and spring force changes, thereby improving response accuracy and reliability near the limp home position.
Implementation Method 1
a spring or springs force the throttle blade to a nominal high-idle condition in case of loss of control of the throttle valve
Data Source
AI summary
A method for controlling a position of an electronic throttle valve of an internal combustion engine is provided. The method includes determining a desired throttle valve position; determining a first feed forward signal based on a rate of change between a previous throttle valve position and the desired throttle valve position; and determining a second feed forward signal based on a comparison of the desired throttle valve position to a limp home position of the throttle valve, in which the throttle valve is biased open by a spring. A summation of the first and second feed forward signals is used to actuate the throttle valve. After the throttle valve has been actuated according to the first and second feed forward signals, the position of the throttle valve is controlled with a feedback controller to obtain the desired throttle valve position.