Engine Speed Controller Using Dynamic PI Gain Maps
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Solution Overview
Problem
Existing engine controllers using PI control strategies face inconsistencies and loss of accuracy in controlling engine speed, particularly at high idle and low speeds, leading to transient oscillations and adverse effects on emissions and vehicle performance.
Innovation Solution
Implementing gain maps correlated with engine speed and temperature, and differentiated for automatic and manual transmissions, to dynamically adjust proportional and integral control gains, enhancing speed regulation and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed gain PI control strategy is used for engine speed control, then the control system is simple to implement, but the engine speed control accuracy and stability deteriorate under dynamic operating conditions
Solution Approach 1:
The patent applies dynamics by transitioning from fixed gains to dynamically adjustable gains. The proportional gain Kp and integral gain Ki are no longer static values but are continuously adjusted based on real-time engine operating conditions including engine speed, acceleration, and torque demands. This dynamic adaptation allows the control system to optimize performance across varying operating states while maintaining reasonable complexity through structured gain adjustment logic.
Solution Approach 2:
The patent implements parameter changes by modifying the control gains Kp and Ki based on operating conditions. The proportional gain is adjusted according to engine speed and acceleration states, while the integral gain is modified based on speed error magnitude and direction. These parameter changes enable the controller to adapt its response characteristics to match current operational requirements, improving both accuracy and stability.
2Measurement precision
If individual devices are controlled with precision, then device-level control accuracy is improved, but transient oscillations and perturbations in engine speed and torque increase
Solution Approach 1:
The patent applies feedback by continuously monitoring engine speed, acceleration, and torque parameters, then using this information to adjust control gains in real-time. The feedback loop detects transient conditions and modifies the proportional and integral gains accordingly, damping oscillations before they propagate through the system. This adaptive feedback mechanism coordinates the precision control of individual devices to maintain overall engine stability.
Solution Approach 2:
The patent uses dynamics to make the control system responsive to transient conditions. By continuously adjusting gains based on real-time operating state detection, the system dynamically adapts to changing conditions, coordinating precise device control with overall engine stability. The dynamic gain adjustment prevents the accumulation of perturbations that would otherwise result from precise but uncoordinated device control.
3Adaptability or versatility
If the engine speed set-point changes as a function of transmission gear selection, then the controller adapts to different driving conditions, but engine speed control repeatability and accuracy deteriorate
Solution Approach 1:
The patent applies parameter changes by adjusting control gains based on transmission gear selection and corresponding speed set-point changes. When the set-point changes due to gear transitions, the system modifies both proportional and integral gains to match the new operating regime. This ensures that control repeatability is maintained across different gears by adapting the controller parameters to each specific operating condition rather than relying on a single fixed gain structure.
Solution Approach 2:
The patent uses dynamics to maintain control repeatability during set-point transitions. The system dynamically detects changes in operating mode and adjusts gains in real-time to compensate for set-point variations. This dynamic adaptation ensures that the controller maintains consistent performance characteristics regardless of which speed set-point is active, achieving repeatability across diverse operating conditions.
Data Source
AI summary
A PI control strategy controls engine speed to an engine speed set-point. A proportional map (36) is populated with data values to be used in calculating the P component of the strategy. An integral map (38) is populated with data values to be used in calculating the I component. Each data value in the maps is correlated with a speed data value representing engine speed (N) and a speed error data value representing the difference between engine speed and engine speed set-point (N_DIF_MAX_LIM). Values for proportional and integral components are selected from the respective maps by processing current engine speed data and current engine speed error data. The strategy uses the values from the maps for controlling engine speed to the speed set-point. Data values from other maps (20 and 24; or 22 and 26) modify the selected values from the proportional and integral maps (36, 38) for transmission type, transmission gear, and engine temperature.