Closed Loop Transmission Torque Control via Dynamic Gain Scheduling
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Solution Overview
Problem
Existing transmission systems face challenges in accurately controlling torque due to slow frequency response and non-linear behavior, leading to oscillation and instability, especially when using simple PID control schemes.
Innovation Solution
Implementing situational gain scheduling and nonlinear control techniques that utilize contextual information such as operator inputs and transmission dynamics to adjust PID control logic, combining open loop and closed loop control with variable gain factors based on machine operating parameters like speed, torque, and direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simple PID control schemes are used, then the control system is simple to implement, but the torque control accuracy deteriorates due to control lag and system non-linearity
Solution Approach 1:
The patent applies dynamic gain scheduling where the PID controller gains are continuously adjusted based on the current operating state of the transmission system. The controller transitions from static gains to dynamic, state-dependent gains that adapt to changing system conditions, thereby maintaining accuracy across different operating points while managing complexity through a structured adaptation mechanism.
Solution Approach 2:
The patent changes the parameters of the PID controller (the gains) based on the identified system state. By modifying the controller parameters dynamically according to operating conditions such as speed and torque levels, the system overcomes the limitations of fixed-gain PID control and achieves accurate torque control across the full operating range without requiring a completely complex control architecture.
2Speed
If gains are increased to speed up response time, then the frequency response improves, but system stability deteriorates causing oscillation and over-control
Solution Approach 1:
The patent implements dynamic gain adjustment where the controller gains are continuously adapted based on the current operating state. During transient conditions or when the system is approaching desired torque, lower gains are applied to prevent oscillation. During steady-state operation or when error is large, higher gains can be used to improve response speed, thus dynamically balancing speed and stability requirements.
Solution Approach 2:
The patent changes the PID controller parameters (gains) based on the identified system state and operating conditions. By adjusting the gain values according to factors such as current torque error, operating speed, and system state, the controller optimizes the balance between response speed and stability, avoiding the fixed trade-off inherent in traditional PID control.
3Loss of time
If excessive gains are applied to overcome control lag, then response time improves, but control ringing and under-damped oscillation occur
Solution Approach 1:
The patent applies dynamic gain scheduling that adjusts controller aggressiveness based on real-time system state. When the system is far from the desired torque or during transient phases, higher gains reduce control lag. When approaching the target or during oscillatory conditions, lower gains prevent ringing and oscillation, thus dynamically eliminating control lag without introducing harmful oscillations.
Solution Approach 2:
The patent changes the controller parameters (PID gains) based on the identified system state to optimize performance. By adjusting gains according to operating conditions, the system reduces control lag when necessary while preventing control ringing and oscillation through state-dependent parameter adaptation, thereby eliminating the harmful effects of excessive gains.
4Stability of the object's composition
If inadequate gains are used, then system stability is maintained, but control lag persists and torque control accuracy deteriorates
Solution Approach 1:
The patent implements dynamic gain adjustment where the controller can apply higher gains when system conditions permit, thereby reducing control lag while maintaining stability. The dynamic adaptation allows the system to use higher gains during conditions where stability is less sensitive, thus eliminating the persistent control lag that would result from consistently using inadequate gains.
Solution Approach 2:
The patent changes the PID controller parameters based on the identified system state, allowing the system to use higher gains when appropriate to reduce control lag. This parameter adaptation enables the controller to overcome the limitations of inadequate fixed gains while maintaining stability through state-dependent adjustment, thereby reducing control lag without sacrificing stability.
Data Source
AI summary
The described system and method provide improved transmission performance and response with closed loop torque feedback by implementing situational gain scheduling and nonlinear control techniques for continuously variable transmissions. The system uses contextual information regarding the operation of the machine to determine a gain to be applied in associated PID control logic. In an embodiment, the determined gain is applied in the integral portion of the closed loop controller.