Electric Brake Torque Commanding for Hysteresis Reversal Stability
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Solution Overview
Problem
Existing brake devices with hysteresis characteristics face challenges in controlling braking force transitions, leading to delayed responses, overshoots, and unnecessary switching, which result in torque pulsation and inefficient motor control.
Innovation Solution
A brake device with a torque command calculation unit and current command calculation unit that includes a specific controller and control adjuster to adjust parameters and set dead zones, allowing precise control of braking force transitions by managing hysteresis characteristics through feedforward terms, control gains, and dead zone settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional motor control is used for electric brakes with hysteresis characteristics, then the braking force can be controlled to reach target values, but response delays and torque pulsation occur during switching between increasing and decreasing braking force
Solution Approach 1:
The control device predicts the required motor torque in advance based on the relationship between braking force and motor torque, and issues torque commands before the braking force actually needs to change. This preliminary action compensates for the hysteresis characteristic and response delay, allowing the braking force to reach target values more accurately and quickly without waiting for the conventional feedback loop to react.
Solution Approach 2:
The control device creates a predictive model that copies the hysteresis characteristic behavior, using the known relationship between braking force and motor torque to anticipate future torque requirements. This model allows the system to pre-calculate appropriate torque commands based on current braking force conditions, effectively simulating and compensating for the inherent delay in the physical system's response.
2Reliability
If conventional motor control is used for electric brakes with hysteresis characteristics, then the braking force can be controlled to reach target values, but unnecessary switching and torque pulsation occur during operation
Solution Approach 1:
By predicting torque requirements in advance and issuing commands proactively, the system avoids the oscillatory behavior that occurs when conventional feedback control repeatedly adjusts torque after detecting deviations. This preliminary action smooths the torque output by anticipating needed changes before they become errors, eliminating the harmful pulsation and unnecessary switching.
3Force
If the relationship between motor torque and braking force has hysteresis characteristics, then the electric brake can generate braking force, but control precision deteriorates during transitions between increasing and decreasing torque
Solution Approach 1:
The control device creates a predictive model that copies the hysteresis characteristic behavior, using the known relationship between braking force and motor torque to anticipate future torque requirements. This model allows the system to pre-calculate appropriate torque commands based on current braking force conditions, effectively simulating and compensating for the inherent delay in the physical system's response.
Solution Approach 2:
The control device dynamically adjusts control parameters based on the predicted torque requirements and current operating conditions. By changing parameters proactively rather than reactively, the system maintains precise control during transitions despite the hysteresis characteristic, adapting the control strategy to match the predicted state of the braking system.
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 smooth and responsive control of braking force transitions, reducing response delays, overshoots, and torque pulsation, ensuring accurate and efficient braking force management.
Implementation Method 1
a motor (60) that generates a torque in response to a drive current
Implementation Method 2
A relationship between the torque of the motor and the braking force generated by the electric brake has a hysteresis characteristics
Data Source
AI summary
A torque command calculation unit calculates a torque command value for a motor based on a required braking force commanded from an external source. A relationship between a motor torque and braking forces generated in the electric brakes has a hysteresis characteristic. When the torque increases, the braking force increases along a positive efficiency line, and when the torque decreases, the braking force decreases along an inverse efficiency line. A specific controller calculates a torque command value to bring an actual load closer to a load command value or to bring an actual position closer to a position command value. A control adjuster adjusts a parameter of a control calculation of the specific controller, or a parameter of a control calculation on an input side or on output side of the specific controller during increase operation, during decrease operation, or during transition between the increase operation and the decrease operation.