Sliding Mode Control for Engine Fuel Flow and Chattering
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Solution Overview
Problem
Modern internal combustion engines with nonlinear dynamics face challenges in achieving optimal fuel quantity and gas flow control due to disturbances and variations, which existing control methods like sliding mode control struggle to address effectively, particularly in maintaining robustness and avoiding chattering.
Innovation Solution
The implementation of a sliding mode control system that uses a dynamic model to determine fuel injection quantity and gas flow rates through a microcomputer-controlled engine control unit, employing a sliding surface to maintain system stability and robustness, with modifications to avoid chattering by replacing the sign function with a saturation function and using a PID controller with feedforward, and calculating changes in flow rates to adjust actuators and fuel quantity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sliding mode control is implemented for engine throttle and cam phase control, then robustness against disturbance is improved, but chattering occurs in the control system
Solution Approach 1:
The control system dynamically adjusts the blending ratio between sliding mode control and conventional PID control based on operating conditions. When the engine operates in regimes where robustness is critical, sliding mode control is emphasized; when chattering becomes problematic, conventional control gains precedence. This dynamic adaptation resolves the contradiction by making the control strategy flexible rather than fixed.
Solution Approach 2:
The system changes control parameters (blending ratio, control gains) based on engine operating conditions to balance robustness and chattering suppression. By monitoring system state and adjusting control parameters accordingly, the system maintains high robustness where needed while minimizing harmful chattering effects in other operating regions.
2Device complexity
If conventional PID control is used for engine parameters, then implementation is simple, but robustness against disturbance is insufficient
Solution Approach 1:
The control system is segmented into multiple control modules: a sliding mode control unit for robust disturbance rejection, a conventional PID control unit for simplicity and stability, and a blending control unit that dynamically combines them. This segmentation allows each module to contribute its strengths while the overall system achieves both robustness and manageable complexity.
Solution Approach 2:
The patent merges sliding mode control and conventional PID control into a unified blended control system. The blending control unit combines the outputs of both control strategies, allowing the system to leverage the robustness of sliding mode control while maintaining the simplicity and stability of conventional PID control where applicable.
3Reliability
If sliding mode control with high robustness is applied to fuel quantity and gas flow control, then disturbance rejection is improved, but control precision and response time may be compromised
Solution Approach 1:
The blended control system incorporates feedback mechanisms that continuously monitor control precision and system response. When precision requirements are high, the feedback loop adjusts the blending ratio to emphasize conventional control strategies. When disturbance rejection is prioritized, sliding mode control gains more weight. This feedback-driven adaptation resolves the precision-robustness trade-off.
Data Source
AI summary
A system and method for using a sliding mode control algorithm to control flow rates from air handling actuators and fuel injectors of an internal combustion engine. The sliding mode control is based on an engine model that represents the engine in terms of pressure and oxygen content states of the intake and exhaust manifolds (as a linear term) and controllable flow rates (as a nonlinear term).