Electric Brake Device Motor Rotation Angle Reset Control
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Solution Overview
Problem
Designing a control system for electric brake devices is challenging due to the non-linear spring constant of the electric brake device, leading to increased calculation load and potential overflow, which can result in worse brake feeling and operation noise.
Innovation Solution
Incorporating a state quantity reset function that resets the motor rotation angle based on predetermined conditions, such as the absolute value of the target braking force and the deviation between the target and estimated braking forces, to maintain a constant braking force and prevent overflow, thereby reducing the likelihood of worse brake feeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the motor rotation angle is included in the state quantity for follow-up control, then the control system design becomes easier (linear control system), but the calculation load increases and variable overflow occurs more frequently
Solution Approach 1:
The patent implements periodic reset of the motor rotation angle state quantity based on predetermined conditions (when absolute value exceeds threshold or overflow detected). This periodic intervention maintains the linear control system benefits while preventing calculation overload, resolving the contradiction between easy control design and manageable calculation complexity.
2Device complexity
If the motor rotation angle is reset frequently to prevent overflow, then calculation load is reduced, but the operation amount varies and brake feeling deteriorates
Solution Approach 1:
The patent employs dynamic reset conditions that consider both the absolute value of motor rotation angle and the change amount of operation amount. By adjusting the reset threshold and evaluating operation change magnitude, the system dynamically determines when resetting is appropriate, balancing calculation load management with maintaining smooth brake feeling.
Solution Approach 2:
The control device monitors the operation amount change and uses this feedback to determine whether to reset the motor rotation angle. When the operation amount change exceeds a predetermined threshold, the reset is inhibited, ensuring brake feeling is not deteriorated. This feedback mechanism resolves the contradiction between overflow prevention and operational smoothness.
3Reliability
If a non-linear spring constant is used in the control parameter, then the control accurately reflects the physical characteristics of the electric brake device, but the control system design becomes difficult
Solution Approach 1:
The patent replaces the mechanical non-linear spring constant parameter with an equivalent linear motor rotation angle state quantity in the control system. This substitution maintains the accuracy of representing the electric brake device's physical characteristics while enabling simpler linear control system design, resolving the contradiction between control accuracy and design ease.
Data Source
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Figure 3(a)~3(b)
AI summary
An electric brake device (DB) includes: a brake rotor; a friction member; friction member contactor; an electric motor (4); braking force estimation unit (28); and a control device (2). The control device (2) has a control system in which a motor rotation angle of the electric motor (4) is included in a state quantity in a control computing of a follow-up control. The control device (2) includes a state quantity reset function unit (25) that resets at least the motor rotation angle to a predetermined value, on the basis of a predetermined condition using at least one of a target braking force, an estimated value of a braking force, an amount of change of a target braking force, an amount of change of an estimated value of a braking force, and a deviation between a target braking force and an estimated value of the braking force.