Electro-Mechanical Brake Contact Point Estimation for Accurate Clamping Force
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Solution Overview
Problem
The existing electro-mechanical brakes face challenges in accurately estimating clamping force due to the complexity and cost associated with mounting force sensors, and the lower accuracy of current sensors in estimating braking force due to measurement noise.
Innovation Solution
The electro-mechanical brake system incorporates a position detection unit to track the piston's position, a current detection unit to measure the motor current, and a contact point calculation unit to accurately determine the contact point where the brake pad starts to engage with the wheel disc, based on specified current values and piston positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a force sensor is mounted to measure clamping force, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent replaces the mechanical force sensor with an electrical measurement system. Specifically, it uses a current sensor to measure motor current and combines this with motor parameters (torque constant, efficiency) and piston position data to calculate clamping force through mathematical relationships, thereby eliminating the need for mechanical force sensors and reducing system complexity
Solution Approach 2:
The patent introduces motor current as an intermediary measurement parameter. Instead of directly measuring clamping force, the system measures motor current which is related to braking force through motor characteristics, and uses this intermediate data along with piston position to infer the actual clamping force, thus avoiding direct force measurement complexity
2Device complexity
If a current sensor is used to estimate clamping force, then device complexity is reduced, but measurement precision deteriorates due to measurement noise
Solution Approach 1:
The patent implements a feedback mechanism where piston position is continuously monitored and fed back into the calculation system. The control unit uses this position feedback to dynamically adjust the clamping force estimation by considering the relationship between piston position and braking force characteristics, thereby compensating for measurement noise in the current sensor data
Solution Approach 2:
The patent changes the approach from direct current-based force estimation to a multi-parameter calculation method. It combines motor current with piston position data and motor parameters (torque constant, efficiency) to calculate clamping force, thereby transforming a single noisy parameter measurement into a multi-parameter estimation that reduces the impact of measurement noise
3Measurement precision
If piston position is monitored to account for hysteresis characteristics, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent makes the piston position detection serve multiple functions: it is used both for determining the contact point between brake pad and disc, and for compensating hysteresis effects in the braking force calculation. This multi-functional use of a single measurement parameter improves accuracy without proportionally increasing system complexity
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
This solution enables accurate estimation of braking force by considering the hysteresis characteristic of the piston's movement, reducing the reliance on force sensors and improving the accuracy of current-based estimations, thereby enhancing the overall performance and cost-effectiveness of the electro-mechanical brake system.
Implementation Method 1
a piston to push a brake pad towards a wheel disc by driving a motor
Implementation Method 2
a pair of brake pads disposed on both sides of the wheel disc, and a piston configured to push the brake pads towards the wheel disc
Data Source
AI summary
The present disclosure provides an electro-mechanical brake including a piston configured to push a brake pad towards a wheel disc by driving a motor, the electro-mechanical brake comprising: a position detection unit that detects the position of the piston; a current detection unit that detects the value of current applied to the motor; and a contact point calculation unit that calculates a contact point, which is where the piston is located when the brake pad starts to come into contact with the wheel disc, based on the position of the piston and the value of current applied to the motor, wherein the contact point calculation unit calculates the contact point based on the position of the piston detected by the position detection unit with respect to a plurality of specified current values and the position of the piston measured with respect to the plurality of specified current values.