Model Predictive Control for Engine Torque Coordination
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Solution Overview
Problem
Traditional engine control systems for internal combustion engines lack accuracy in controlling engine output torque and fail to provide rapid responses to control signals, as well as coordinate torque control among various devices affecting engine output.
Innovation Solution
An engine control system that employs a prediction module to determine predicted torques for future times, a cost module to assess these predictions against torque requests, and a selection module to choose target values based on cost, using model predictive control (MPC) to optimize engine actuators such as throttle, wastegate, and spark timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional engine control systems are used, then the system structure is simple, but the torque control accuracy is insufficient and response speed is slow
Solution Approach 1:
The control system performs preliminary actions by predicting future torque values and determining optimal target values for multiple future time points before they are needed. The prediction module forecasts torque at future time points, and the determination module pre-calculates target values that will achieve desired torque trajectories, allowing the engine to respond proactively rather than reactively to torque requests.
Solution Approach 2:
The system implements dynamic control by continuously adjusting target values based on predicted future torque requirements. The control approach transitions from static, reactive control to dynamic, predictive control where target values are continuously optimized based on forecasted engine states and future torque demands, enabling adaptive response to changing operating conditions.
2Speed
If traditional control methods are used, then the control logic is simple, but the response speed to torque requests is slow
Solution Approach 1:
The system performs preliminary actions by predicting future torque values and determining optimal target values for multiple future time points before they are needed. The prediction module forecasts torque at future time points, and the determination module pre-calculates target values that will achieve desired torque trajectories, allowing the engine to respond proactively rather than reactively to torque requests.
Solution Approach 2:
The control system implements feedback mechanisms where actual torque measurements are continuously compared with predicted torque values, and the prediction model is updated based on prediction errors. This closed-loop feedback ensures that the predictive control adapts to actual engine behavior, improving response accuracy while maintaining the benefits of predictive control.
3Reliability
If multiple actuators are controlled independently, then each actuator can be optimized individually, but coordination among actuators is poor
Solution Approach 1:
The control system merges the control of multiple actuators into a unified predictive control framework. Instead of independently controlling throttle, spark timing, and other actuators, the system determines coordinated target values for all actuators simultaneously based on predicted future torque requirements, ensuring that all actuators work together harmoniously to achieve the desired torque trajectory.
Solution Approach 2:
The prediction module serves multiple functions by forecasting torque values that are used for both control optimization and coordination of multiple actuators. The same predictive model that optimizes individual actuator performance also provides the foundation for coordinating their interactions, making the control system more versatile and efficient.
Data Source
AI summary
A prediction module, based on a set of possible target values for M future times and a model of an engine, determines predicted torques of the engine for the M future times, respectively. M is an integer greater than one. A cost module determines a cost for the set of possible target values based on comparisons of the predicted torques for the M future times with engine torque requests for the M future times, respectively. A selection module, based on the cost, selects the set of possible target values from a group including the set of possible target values and N other sets of possible target values, wherein N is an integer greater than zero, and sets target values based on the selected set of possible target values. An actuator module controls an engine actuator based on a first one of the target values.