Electric Linear Actuator Overshoot Suppression
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Solution Overview
Problem
Existing electric brake devices experience excessive overshoot and poor brake response due to non-linearity in load detection, leading to brake shock and inadequate responsiveness, especially when applying small braking forces.
Innovation Solution
An electric linear motion actuator with an overshoot suppression control mechanism that reduces the number of motor revolutions just before contact, using a combination of load and rotation angle sensors to accurately determine the position of the friction pad relative to the brake disk, thereby controlling the motor to prevent overshoot and ensure precise load application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the electric motor rotates at high speed to improve brake responsiveness, then the brake response is improved, but excessive overshoot and brake shock occur when the friction pad contacts the brake disk
Solution Approach 1:
The system performs preliminary detection of the friction pad's position relative to the brake disk using a rotation angle sensor. When the sensor detects that the friction pad is approaching the brake disk (within a predetermined angle range), the control unit preemptively reduces the motor's rotational speed before contact occurs. This preliminary action prevents the inertial energy from causing excessive overshoot and brake shock while still maintaining fast brake response.
Solution Approach 2:
The system uses a rotation angle sensor to continuously monitor the motor's rotation angle and provide feedback to the control unit. Based on this feedback, the control unit dynamically adjusts the motor's rotational speed: maintaining high speed when the friction pad is far from the brake disk for fast response, and reducing speed when the friction pad approaches contact to prevent overshoot. This closed-loop feedback control resolves the contradiction between speed and overshoot.
2Object-generated harmful factors
If the motor speed is reduced before contact to prevent overshoot, then brake shock is minimized, but brake responsiveness deteriorates
Solution Approach 1:
The system dynamically adjusts the motor's rotational speed based on the real-time position of the friction pad relative to the brake disk. The rotation angle sensor continuously monitors the motor's rotation angle, and the control unit varies the motor speed accordingly: high speed during most of the approach phase for fast response, and reduced speed only in the final approach phase (within predetermined angle range) to prevent brake shock. This dynamic adjustment maintains overall brake responsiveness while minimizing harmful effects.
3Measurement precision
If feedback control gain is increased to improve load precision, then load accuracy is improved, but overshoot occurs due to inertial energy of the motor
Solution Approach 1:
The system performs preliminary speed reduction based on rotation angle detection before the friction pad contacts the brake disk. By reducing the motor's rotational speed in advance (when within the predetermined angle range of contact), the inertial energy is minimized before load application begins. This allows the feedback control to operate with higher gain for improved load accuracy without causing excessive overshoot, as the motor's inertial energy has already been reduced by the preliminary action.
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 effectively reduces overshoot and enhances brake responsiveness by allowing the friction pad to move faster while minimizing brake shock, providing a more stable and responsive braking system.
Implementation Method 1
an electric motor (15)
Implementation Method 2
a motion converting mechanism (B) that converts the rotational motion of the electric motor (15) into a linear motion of a linear moving member (A)
Implementation Method 3
a load sensor (14) that detects the magnitude of a load applied to a brake disk (2) from a friction pad (7)
Data Source
AI summary
An electric linear motion actuator includes an electric motor, a motion converting mechanism that converts the rotational motion of the electric motor into a linear motion of a linear moving member, a load sensor that detects the magnitude of the load applied to the brake disk from the linear moving member, and a controller that performs feedback control on the electric motor based on the difference between the load detected by the load sensor and a load command value. The controller reduces the number of revolutions of the electric motor when the linear moving member moves into a predetermined zone immediately before the position where the clearance between the linear moving member and the brake disk becomes zero.