An electromechanical brake system contact point identification system and method thereof

Abstract

The application relates to an electromechanical brake system contact point identification system and a method thereof, the system comprising an initial contact point detection device, a sine position closed-loop control module and a mean value calculation module, and the method comprising the following steps: detecting an initial contact point, i.e. the position of a motor rotor when a brake pad contacts a brake disc; taking the initial contact point as a bias of a sine position instruction, setting a sine position signal frequency, and performing sine position closed-loop control through a motor control module; obtaining multiple contact point data in the process of the sine position closed-loop control, and calculating the Gaussian distribution mean value of the multiple contact point data, i.e. obtaining a contact point identification result. Compared with the prior art, the application can reduce the error of contact point identification, avoid the leading and lagging phenomena of contact point identification, and provide more accurate initial conditions for clamping force estimation.

Description

Technical Field

[0001] This invention relates to the field of automotive brake-by-wire technology, and in particular to an electromechanical braking system contact point identification system and method thereof. Background Technology

[0002] With the development trends of "electrification" and "intelligentization" in automobiles, braking systems are undergoing a new transformation. In terms of "electrification," distributed drive electric vehicles employ regenerative braking technology to recover braking energy. To maximize braking energy recovery, the braking force needs to be decoupled from the brake pedal, achieving coordinated matching and precise control of motor torque and friction braking force. In terms of "intelligentization," a complete intelligent driving system consists of an environmental perception system, a central decision-making system, and a lower-level control system, with the brake actuator being a key component for achieving chassis-domain control.

[0003] To meet these requirements, brake-by-wire systems were developed. Brake-by-wire systems can be divided into two types: electro-hydraulic braking and electro-mechanical braking. Electro-hydraulic braking uses an electro-hydraulic control method, retaining most hydraulic components, but suffers from slow braking response, complex piping layout, and brake fluid leakage. Electro-mechanical braking completely eliminates the hydraulic circuit, using a wheel-side motor to drive the actuator and generate clamping force. Compared to electro-hydraulic braking, there is no lengthy hydraulic line as an intermediary for brake force transmission, thus eliminating the hysteresis effect of hydraulic oil and resulting in a faster braking response; higher control precision, facilitating integration with other active safety control systems; and the elimination of electronic boosters, solenoid valves, and hydraulic components, reducing system size and weight, and simplifying installation and maintenance. Furthermore, the brake release is driven by a motor, rather than using elastic seals to return the piston, resulting in lower braking drag torque.

[0004] For electromechanical braking systems, the rotor position when the friction pad contacts the brake disc is defined as the contact point. Based on the contact point, the braking clamping process is divided into the brake gap elimination stage and the clamping force generation stage. In actual braking, after the motor receives the braking command, it first needs to overcome static friction and actuator load. Therefore, when the brake is started, if the braking command rises too quickly, the motor current will experience a significant increase. At this time, simply using the current signal for contact point identification will result in contact point identification being ahead of time. If the threshold value set for contact point identification is too large, it will lead to contact point identification being behind time, thus causing a very large error in the clamping force estimation.

[0005] The rate of increase of the braking command will affect the identification of the contact point. Under closed-loop control, when the target command increases too quickly, the brake pads will move towards the brake disc at a faster rate, and the rotor will make more angular displacement per unit time. However, since the sampling period of the system and the transmission frequency of the sensor signal are discrete and fixed, when the sensor signal exceeds a certain threshold and the system fixes the current rotor position as the contact point position, the identified contact point position will shift as the command rate increases. Summary of the Invention

[0006] The purpose of this invention is to overcome the defects of the prior art by providing an electromechanical braking system contact point identification system and method, which can reduce the error of contact point identification, avoid the leading and lagging phenomena of contact point identification, and provide more accurate initial conditions for clamping force estimation.

[0007] The objective of this invention can be achieved through the following technical solution: an electromechanical braking system contact point identification system, comprising an initial contact point detection device, a sinusoidal position closed-loop control module, and an average value calculation module, wherein the initial contact point detection device is used to detect the position of the motor rotor when the brake pad contacts the brake disc;

[0008] The sinusoidal position closed-loop control module uses the initial contact point as the bias of the sinusoidal position command, sets the sinusoidal position tracking frequency, performs position tracking, and obtains data from multiple contact points.

[0009] The mean calculation module is used to calculate the Gaussian distribution mean of multiple contact point data, which is the actual contact point identified.

[0010] Furthermore, the initial contact point detection device includes a motor position sensor, a current sensor, a rotational acceleration calculation module, and a threshold comparison module. The motor position sensor is used to acquire the position signal of the motor rotor in real time.

[0011] The current sensor is used to acquire the current signal of the drive motor in real time;

[0012] The angular acceleration calculation module calculates the angular acceleration of the rotor based on the position signal of the motor rotor;

[0013] The threshold comparison module is used to compare the rotor's angular acceleration with a preset threshold and the current signal with a preset current threshold, respectively.

[0014] Furthermore, the rotational acceleration calculation module includes an angular velocity calculation unit and an angular acceleration calculation unit, which are used to calculate the angular velocity and angular acceleration of the rotor in sequence.

[0015] Furthermore, the threshold comparison module includes a first angular acceleration comparison unit, a second angular acceleration comparison unit, and a current comparison unit. The first angular acceleration comparison unit is used to determine whether the rotor's angular acceleration is greater than a first threshold. If it is, the second angular acceleration comparison unit continues to determine whether the rotor's angular acceleration is greater than a second threshold. Otherwise, the motor is directly controlled according to the braking force command output by the ECU (Electronic Control Unit).

[0016] If the rotor's angular acceleration is greater than the second threshold, the current comparison unit will continue to determine whether the current signal is greater than the preset current threshold; otherwise, the motor will be controlled directly according to the braking force command output by the ECU.

[0017] If the current signal is greater than the preset current threshold, the rotor position corresponding to the current exceeding the preset current threshold is used as the initial contact point; otherwise, the motor is controlled directly according to the braking force command output by the ECU.

[0018] Furthermore, the initial contact point detection device includes a clamping force sensor and a threshold comparison unit, wherein the clamping force sensor is used to acquire the clamping force signal of the actuator in real time;

[0019] The threshold comparison unit is used to compare the clamping force signal with a preset force threshold. If the clamping force signal is greater than the preset force threshold, the rotor position corresponding to the time when the preset force threshold is exceeded is taken as the initial contact point.

[0020] A method for identifying contact points in an electromechanical braking system includes the following steps:

[0021] S1. Detect the initial contact point, that is, the position of the motor rotor when the brake pads contact the brake disc;

[0022] S2. Use the initial contact point as the offset of the sinusoidal position command, set the frequency of the sinusoidal position signal, and perform sinusoidal position closed-loop control through the motor control module.

[0023] S3. During the sinusoidal position closed-loop control process, acquire multiple contact point data, calculate the mean of the Gaussian distribution of the multiple contact point data, and obtain the contact point identification result.

[0024] Furthermore, step S1 specifically employs a combination of current signal and angular acceleration signal to detect the initial contact point:

[0025] The real-time position of the motor rotor is obtained based on the motor position sensor, and the rotor angular velocity and rotor angular acceleration are calculated accordingly.

[0026] To avoid premature contact point identification caused by the rapid increase in current provided by the motor during the static friction and load phases, two rotor angular acceleration threshold crossing judgments are required before current threshold judgment. After the rotor angular acceleration signal completes the two threshold crossings, the current signal threshold judgment is performed. If the motor current signal collected at this time exceeds the preset current threshold, the rotor position at this time is recorded as the initial contact point.

[0027] Furthermore, the formulas for calculating the rotor angular velocity and rotor angular acceleration are as follows:

[0028]

[0029] Where θ is the rotor angular displacement, i.e. the real-time position of the motor rotor, w is the rotor angular velocity, and α is the rotor angular acceleration.

[0030] Furthermore, step S1 specifically employs a clamping force signal discrimination method to detect the initial contact point:

[0031] The clamping force signal of the actuator is obtained based on the clamping force sensor. When the clamping force signal is greater than the preset force threshold, the rotor position at this time is recorded as the initial contact point.

[0032] Furthermore, step S2 specifically involves setting the frequency of the sinusoidal position signal to be less than or equal to 1Hz.

[0033] Furthermore, step S2 specifically involves sinusoidal position closed-loop control based on a three-loop position control algorithm. The three-loop position control algorithm includes position closed-loop control, speed closed-loop control, and current closed-loop control connected in series. The position closed-loop control input is the error between the target position and the actual position, and the output is the target speed.

[0034] The input to the speed closed-loop control is the error between the target speed and the actual speed, and the output is the target current.

[0035] The input to the current closed-loop control is the error between the target current and the actual current, and the output is the target voltage.

[0036] Compared with the prior art, the present invention has the following advantages:

[0037] This invention comprises an initial contact point detection device, a sinusoidal position closed-loop control module, and a mean calculation module. The initial contact point detection device detects the motor rotor position when the brake pad contacts the brake disc. The sinusoidal position closed-loop control module uses the initial contact point as the offset for the sinusoidal position command, sets a sinusoidal position tracking frequency, and performs position tracking to acquire multiple contact point data. The mean calculation module calculates the Gaussian distribution mean of the multiple contact point data to identify the actual contact point. This avoids contact point recognition lead caused by signal overshoot, thereby reducing the error in clamping force estimation. Furthermore, by identifying multiple sets of data through sinusoidal position control and averaging the obtained data, the contact point recognition error is further reduced, providing a more accurate starting point for clamping force estimation.

[0038] The initial contact point detection device of this invention adopts a combination of position sensor signal and current sensor signal, or a single clamping force sensor signal, and uses a corresponding threshold comparison unit to judge the signal and determine the initial contact point. This can effectively improve the detection accuracy of the initial contact point. Moreover, in practical applications, the detection of the initial contact point can be achieved by selecting one of the methods according to the actual sensor installation situation, which greatly improves the applicability of this invention.

[0039] In this invention, if the initial contact point detection is achieved by using a combination of current signal and angular acceleration signal discrimination method, the design requires two rotor angular acceleration threshold crossing judgments before the current threshold judgment. That is, after the rotor angular acceleration signal completes two threshold crossings, the current signal threshold judgment is then performed. This can effectively avoid the contact point recognition being premature due to the rapid increase in current provided by the motor during the static friction and load phases. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the system structure of the present invention;

[0041] Figure 2 This is a schematic diagram of the method flow of the present invention;

[0042] Figure 3 This is a schematic diagram illustrating the application process of an example.

[0043] Figure 4 This is a schematic diagram of the sinusoidal position closed-loop control process;

[0044] Figure 5 This is a schematic diagram of the contact point identification curve in the embodiment;

[0045] Figure 6 This is a schematic diagram illustrating the distribution of contact points identified in the embodiment;

[0046] The markings in the diagram are as follows: 1. Initial contact point detection device; 2. Sine position closed-loop control module; 3. Mean value calculation module. Detailed Implementation

[0047] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0048] Example

[0049] like Figure 1 As shown, an electromechanical braking system contact point identification system includes an initial contact point detection device 1, a sinusoidal position closed-loop control module 2, and an average value calculation module 3. The initial contact point detection device 1 is used to detect the position of the motor rotor when the brake pad contacts the brake disc.

[0050] The sinusoidal position closed-loop control module 2 uses the initial contact point as the bias of the sinusoidal position command, sets the sinusoidal position tracking frequency, performs position tracking, and obtains data from multiple contact points.

[0051] The mean calculation module 3 is used to calculate the Gaussian distribution mean of multiple contact point data, which is the actual contact point identified.

[0052] Specifically, the initial contact point detection device 1 can adopt two schemes:

[0053] The first scheme, the initial contact point detection device 1, includes a motor position sensor, a current sensor, a rotational acceleration calculation module and a threshold comparison module. The motor position sensor is used to collect the position signal of the motor rotor in real time.

[0054] The current sensor is used to acquire the current signal of the drive motor in real time;

[0055] The angular acceleration calculation module calculates the angular acceleration of the rotor based on the position signal of the motor rotor. The angular acceleration calculation module includes an angular velocity calculation unit and an angular acceleration calculation unit, which are used to calculate the angular velocity and angular acceleration of the rotor in sequence.

[0056] The threshold comparison module is used to compare the rotor's angular acceleration with a preset threshold and the current signal with a preset current threshold, respectively. Specifically, it includes a first angular acceleration comparison unit, a second angular acceleration comparison unit, and a current comparison unit. The first angular acceleration comparison unit is used to determine whether the rotor's angular acceleration is greater than the first threshold. If it is, the second angular acceleration comparison unit continues to determine whether the rotor's angular acceleration is greater than the second threshold. Otherwise, the motor is directly controlled according to the braking force command output by the ECU.

[0057] If the rotor's angular acceleration is greater than the second threshold, the current comparison unit will continue to determine whether the current signal is greater than the preset current threshold; otherwise, the motor will be controlled directly according to the braking force command output by the ECU.

[0058] If the current signal is greater than the preset current threshold, the rotor position corresponding to the current exceeding the preset current threshold is used as the initial contact point; otherwise, the motor is controlled directly according to the braking force command output by the ECU.

[0059] The second scheme, the initial contact point detection device 1, includes a clamping force sensor and a threshold comparison unit. The clamping force sensor is used to collect the clamping force signal of the actuator in real time; the threshold comparison unit is used to compare the clamping force signal with a preset force threshold. If the clamping force signal is greater than the preset force threshold, the rotor position corresponding to the time when the preset force threshold is exceeded is taken as the initial contact point.

[0060] Therefore, the above two detection schemes are designed so that when the clamping force sensor is not installed due to space and cost considerations of the wheel end caliper, or when the clamping force sensor of the actuator fails, the initial contact point of the brake can be obtained by combining the current signal and the rotor angular acceleration signal based on the current sensor signal and displacement sensor signal of the drive motor.

[0061] Using the above system, a method for identifying contact points in an electromechanical braking system is implemented, such as... Figure 2 As shown, it includes the following steps:

[0062] S1. Detect the initial contact point, that is, the position of the motor rotor when the brake pads contact the brake disc;

[0063] S2. Use the initial contact point as the offset of the sinusoidal position command, set the frequency of the sinusoidal position signal, and perform sinusoidal position closed-loop control through the motor control module.

[0064] S3. During the sinusoidal position closed-loop control process, acquire multiple contact point data, calculate the mean of the Gaussian distribution of the multiple contact point data, and obtain the contact point identification result.

[0065] In step S1, if a combination of current signal and angular acceleration signal is used to detect the initial contact point, the specific process is as follows:

[0066] The real-time position of the motor rotor is obtained based on the motor position sensor, and the rotor angular velocity and rotor angular acceleration are calculated from this. The formulas for calculating the rotor angular velocity and rotor angular acceleration are as follows:

[0067]

[0068] Where θ is the rotor angular displacement, i.e. the real-time position of the motor rotor, w is the rotor angular velocity, and α is the rotor angular acceleration. It should be noted that in practical applications, since it is difficult to install a piston displacement sensor in the transmission mechanism, the axial displacement of the piston can also be converted into the angular displacement of the rotor through the transmission ratio of the transmission mechanism.

[0069] To avoid premature contact point identification caused by the rapid increase in current provided by the motor during the static friction and load phases, two rotor angular acceleration threshold crossing judgments are required before current threshold judgment. After the rotor angular acceleration signal completes the two threshold crossings, the current signal threshold judgment is performed. If the motor current signal collected at this time exceeds the preset current threshold, the rotor position at this time is recorded as the initial contact point.

[0070] In step S1, if the clamping force signal discrimination method is used to detect the initial contact point, the specific process is as follows:

[0071] The clamping force signal of the actuator is obtained based on the clamping force sensor. When the clamping force signal is greater than the preset force threshold, the rotor position at this time is recorded as the initial contact point.

[0072] This embodiment applies the above-described technical solution, such as Figure 3 As shown, the ECU sends braking force commands to the motor. The motor rotor first overcomes static friction and load, and then begins to rotate. The rotor's rotational motion is converted into axial translational motion towards the brake disc through a reduction mechanism and a motion conversion mechanism. When the brake pads contact the brake disc, the rotor position at this moment is recorded as the initial contact point. After the brake pads contact the brake disc, the clamping force begins to increase. The motor control module implements closed-loop control based on feedback signals from current sensors, position sensors, and clamping force sensors. The initial contact point is detected through a combination of current sensor and position sensor signals, or a method based on clamping force sensor signals.

[0073] The first method uses a combination of current signal and rotational acceleration signal to detect the initial contact point.

[0074] The real-time position of the motor rotor is obtained, and the position of the motor rotor when the brake pad contacts the brake disc is defined as the contact point, which is the starting point for clamping force estimation.

[0075] The position signal of the motor rotor is obtained using the motor's position sensor, and the angular velocity and angular acceleration of the motor rotor are calculated.

[0076] To obtain the current signal of the drive motor, in order to avoid the contact point identification being premature due to the rapid increase in current provided by the motor during the overcoming of static friction and load stages, two rotor angular acceleration threshold crossing judgments are required before the current threshold judgment is performed. After the rotor angular acceleration signal has completed the two threshold crossings, the current signal threshold judgment is then performed. If the motor current exceeds the current threshold at this time, the rotor position at this time is recorded as the initial contact point, that is, the starting point of clamping force estimation.

[0077] The second method uses a clamping force sensor signal discrimination method to detect the initial contact point.

[0078] The actuator's braking clamping force is obtained. When the braking clamping force is greater than the clamping force threshold, the rotor position at this time is set as the contact point, which is the starting point of the clamping force estimation. After the brake pad contacts the brake disc, the clamping force begins to rise. When the clamping force signal is greater than the preset force threshold, the rotor position at this time is recorded as the initial contact point.

[0079] After obtaining the initial contact point, the initial contact point is used as the bias of the sinusoidal position command. A lower sinusoidal position signal frequency is selected, such as 1Hz or lower (1Hz is set in this embodiment). The sinusoidal position closed-loop control is performed by the motor control module, so that the rotor performs sinusoidal position tracking near the contact point and repeatedly crosses the signal threshold to obtain multiple sets of contact point data. By taking the average value, a more accurate actual contact point is obtained. This actual contact point can be used as the initial starting point for clamping force estimation or the initial starting point for brake release.

[0080] When performing sinusoidal position closed-loop control, a three-loop position control is performed based on the current signal, speed signal, and position signal obtained from the current sensor signal and the position sensor signal. That is, based on the current closed loop, speed closed loop, and position closed-loop control, a series three-loop position control is obtained, in the order of position loop - speed loop - current loop:

[0081] The input to the position closed-loop control is the error between the target position and the actual position, and the output is the target speed.

[0082] The input to the speed closed-loop control is the error between the target speed and the actual speed, and the output is the target current.

[0083] The input to the current closed-loop control is the error between the target current and the actual current, and the output is the target voltage.

[0084] Therefore, based on the three-loop position control algorithm, a sinusoidal position tracking command is input to the closed-loop control, causing the motor rotor to rotate back and forth in both directions near the contact point. The identification is based on the signal repeatedly crossing the signal threshold, acquiring multiple sets of contact point signal data. By taking the average, the contact point with the smallest error is obtained as the starting point for clamping force estimation.

[0085] like Figure 4As shown, the motor control module achieves sinusoidal position tracking control of rotor displacement through three closed-loop control: current closed loop, speed closed loop, and position closed loop.

[0086] like Figure 5 As shown, after detecting the initial contact point, the sinusoidal tracking command uses the initial contact point as a sinusoidal bias and sets the sinusoidal position tracking frequency to 1Hz for position tracking. Whenever the signal exceeds the threshold, a contact point data will be generated. Repeating this sinusoidal tracking condition can obtain the probability distribution of the contact points.

[0087] like Figure 6 As shown, the contact point data obtained by the sinusoidal position tracking command conforms to a Gaussian distribution. The mean of the Gaussian distribution is used as the final identified contact point. This actual contact point can be used as the initial starting point for clamping force estimation or the initial starting point for brake release.

[0088] In summary, this scheme defines the contact point as the rotor position when the brake pad contacts the brake disc; it achieves rotor position control through a position closed-loop control method; the contact point is identified using the position and current sensor signals from the drive motor itself, or the force sensor from the actuator; after obtaining the initial contact point data, it is used as the bias for sinusoidal position tracking, and a low frequency is set for initial sinusoidal position closed-loop control. Reliable contact point data is obtained by averaging the results. This scheme effectively reduces the error in contact point identification and provides a more accurate initial point for clamping force estimation.

Claims

1. A contact point identification system for an electromechanical braking system, characterized in that, It includes an initial contact point detection device (1), a sinusoidal position closed-loop control module (2), and an average value calculation module (3). The initial contact point detection device (1) is used to detect the position of the motor rotor when the brake pad contacts the brake disc. The sinusoidal position closed-loop control module (2) uses the initial contact point as the bias of the sinusoidal position command, sets the sinusoidal position tracking frequency, performs position tracking, and obtains multiple contact point data. The mean calculation module (3) is used to calculate the Gaussian distribution mean of multiple contact point data, which is the actual contact point identified. The initial contact point detection device (1) includes a motor position sensor, a current sensor, a rotational acceleration calculation module and a threshold comparison module. The motor position sensor is used to collect the position signal of the motor rotor in real time. The current sensor is used to acquire the current signal of the drive motor in real time; The angular acceleration calculation module calculates the angular acceleration of the rotor based on the position signal of the motor rotor; The threshold comparison module is used to compare the rotor's angular acceleration with a preset threshold and the current signal with a preset current threshold, respectively. The threshold comparison module includes a first angular acceleration comparison unit, a second angular acceleration comparison unit, and a current comparison unit. The first angular acceleration comparison unit is used to determine whether the rotor's angular acceleration is greater than a first threshold. If it is, the second angular acceleration comparison unit continues to determine whether the rotor's angular acceleration is greater than a second threshold. Otherwise, the motor is directly controlled according to the braking force command output by the ECU. If the rotor's angular acceleration is greater than the second threshold, the current comparison unit will continue to determine whether the current signal is greater than the preset current threshold; otherwise, the motor will be controlled directly according to the braking force command output by the ECU. If the current signal is greater than the preset current threshold, the rotor position corresponding to the current exceeding the preset current threshold is used as the initial contact point; otherwise, the motor is controlled directly according to the braking force command output by the ECU.

2. The contact point identification system for an electromechanical braking system according to claim 1, characterized in that, The rotational acceleration calculation module includes an angular velocity calculation unit and an angular acceleration calculation unit, which are used to calculate the angular velocity and angular acceleration of the rotor in sequence.

3. The contact point identification system for an electromechanical braking system according to claim 1, characterized in that, The initial contact point detection device (1) includes a clamping force sensor and a threshold comparison unit. The clamping force sensor is used to collect the clamping force signal of the actuator in real time. The threshold comparison unit is used to compare the clamping force signal with a preset force threshold. If the clamping force signal is greater than the preset force threshold, the rotor position corresponding to the time when the preset force threshold is exceeded is taken as the initial contact point.

4. A method for identifying contact points in an electromechanical braking system using the contact point identification system of claim 1, characterized in that, Includes the following steps: S1. Detect the initial contact point, that is, the position of the motor rotor when the brake pads contact the brake disc; S2. Use the initial contact point as the offset of the sinusoidal position command, set the frequency of the sinusoidal position signal, and perform sinusoidal position closed-loop control through the motor control module. S3. During the sinusoidal position closed-loop control process, acquire multiple contact point data, calculate the mean of the Gaussian distribution of the multiple contact point data, and obtain the contact point identification result.

5. The method for identifying contact points in an electromechanical braking system according to claim 4, characterized in that, Step S1 specifically uses a combination of current signal and angular acceleration signal to detect the initial contact point: The real-time position of the motor rotor is obtained based on the motor position sensor, and the rotor angular velocity and rotor angular acceleration are calculated accordingly. To avoid premature contact point identification caused by the rapid increase in current provided by the motor during the static friction and load phases, two rotor angular acceleration threshold crossing judgments are required before current threshold judgment. After the rotor angular acceleration signal completes the two threshold crossings, the current signal threshold judgment is performed. If the motor current signal collected at this time exceeds the preset current threshold, the rotor position at this time is recorded as the initial contact point.

6. The method for identifying contact points in an electromechanical braking system according to claim 5, characterized in that, The formulas for calculating the rotor angular velocity and rotor angular acceleration are as follows: Where θ is the rotor angular displacement, i.e. the real-time position of the motor rotor, w is the rotor angular velocity, and α is the rotor angular acceleration.

7. The method for identifying contact points in an electromechanical braking system according to claim 4, characterized in that, Step S1 specifically involves using a clamping force signal discrimination method to detect the initial contact point: The clamping force signal of the actuator is obtained based on the clamping force sensor. When the clamping force signal is greater than the preset force threshold, the rotor position at this time is recorded as the initial contact point.

8. The method for identifying contact points in an electromechanical braking system according to claim 4, characterized in that, Step S2 specifically involves setting the frequency of the sinusoidal position signal to be less than or equal to 1Hz.

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