CN101545759B - Vehicle brake pedal travel measuring method - Google Patents
Vehicle brake pedal travel measuring method Download PDFInfo
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- CN101545759B CN101545759B CN2009100221732A CN200910022173A CN101545759B CN 101545759 B CN101545759 B CN 101545759B CN 2009100221732 A CN2009100221732 A CN 2009100221732A CN 200910022173 A CN200910022173 A CN 200910022173A CN 101545759 B CN101545759 B CN 101545759B
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Abstract
The invention relates to the technique of brake pedal travel measurement, and discloses a vehicle brake travel measuring device and a measuring method thereof. An image acquisition device is fixed at one side of a brake pedal to acquire the motion images of the brake pedal; a computer is electrically connected with the image acquisition device to receive the motion images of the brake pedal, identifies the different obtained positions of the brake pedal in different time through the images, obtains the travel of the brake pedal through the geometric transformation, and further calculates and obtains the motion speed and acceleration of the brake pedal.
Description
Technical field
The present invention relates to the brake-pedal travel measuring technique, relate in particular to a kind of measurement mechanism and measuring method thereof of vehicle brake pedal travel.
Technical background
In the automobile test field, usually need the record driver to use the correlation circumstance of brake pedal, the light and heavy degree that uses the frequency of brake pedal and step on brake pedal as the driver.The weight whether use of brake pedal reaches pedal has directly reacted the operating conditions of driver to vehicle, be to need an accurately parameter of record in the automobile experiment process, this parameter can be reacted the driver behavior behavior of driver in the automobile experiment process exactly, with vehicle, can react this driver's driving behavior characteristic after the road environment parametric synthesis, and react influencing each other between driver, vehicle, the road three really, therefore in automobile experiment, need usually to use relevant measuring system to measure the stroke of brake pedal.
At present, brake-pedal travel measured two kinds of methods usually, first kind is that a pedal force collection plate is installed on brake pedal, the foot that is the driver applies damping force earlier to this pedal force collection plate, the damping force that again driver applied of collection plate passes to brake pedal then, what this method was directly measured is brake pedal force, and pedal force is converted obtains the stroke of brake pedal then.Second method is to adopt special Linear displacement transducer, need dismantle brake pedal when using Linear displacement transducer, then this Linear displacement transducer is installed in tie point inside, pedal top, again brake pedal is reset into original state after the installation.But these two kinds of methods that present stage uses all exist certain problem.For first method, what it was directly measured is not the stroke of brake pedal, but the driver steps on the power of brake pedal, by pedal force in the transfer process of pedal travel, the transformational relation of different automobile types is different, therefore, use this method also to need to carry out extra pedal rigidity staking-out work, obtain transformational relation from the pedal force to the pedal travel with this; In addition, because this method has been installed an other tabular sensor on brake pedal, the driver is not the direct control brake pedal, such consequence makes the force feedback process of the perception brake pedal that the driver can't be correct, usually be called and lose feel, have influence on driver's normal running, thereby can influence the authenticity of experiment.For second method, its measurement data is accurate, and the stroke of reaction brake pedal that can be correct is more a kind of method of using at present; But, the problem that this method mainly exists is the integrity problem of brake system, the brake system of automobile is the system of a strict control reliability of needs, in the test for sensor installation, need dismantle brake system, to bring the potential safety hazard of inefficacy to brake system like this, the security of influence test.
Summary of the invention
One object of the present invention is to provide the measurement mechanism of the vehicle brake pedal travel that a kind of investment cost is few, simple to operate, measuring accuracy is high.
Another object of the present invention is to provide a kind of measuring method of vehicle brake pedal travel, based on the measurement mechanism of above-mentioned vehicle brake pedal travel.
Ultimate principle of the present invention is by using an image collecting device (video camera) to gather the moving image of brake pedal in real time, and the moving image with brake pedal transfers to computing machine then.Utilize image processing software in the system, obtain the accurate position of brake pedal in image by image recognition, because the invariant position of the relative brake pedal of video camera, therefore, the different brake pedal position process simple geometric conversion constantly that image recognition obtains just can access the stroke of brake pedal, and then can calculate speed and the acceleration that brake pedal moves, reflect the process of driver's operation brake pedal accurately.
In order to reach above-mentioned technical purpose, the present invention is achieved by the following technical solutions.
1, a kind of measurement mechanism of vehicle brake pedal travel is characterized in that, comprising:
Image collecting device is fixed on brake pedal one side, gathers the moving image of brake pedal;
Computing machine, be electrically connected image collecting device, receive the moving image of brake pedal, the different brake pedal position constantly that obtain by image recognition, obtain the stroke of brake pedal through geometric transformation, and then calculate the movement velocity and the acceleration of brake pedal.
The further improvement and the characteristics of the technical program are:
Described image collector is changed to camera; Described camera adopts culminant star YJS-01 USB2.0 camera.
Described image collecting device is arranged on the brake pedal left side.
Described image collecting device is provided with the shooting light source, and the shooting light source is the LED lamp.
2, a kind of measuring method of vehicle brake pedal travel, based on the measurement mechanism of above-mentioned vehicle brake pedal travel, image collector is changed to camera, it is characterized in that, may further comprise the steps:
Camera calibration is at first made scaling board, and uncalibrated image is set on the scaling board, conversion scaling board position, and the camera acquisition image utilizes these images to demarcate, and obtains parameters of pick-up head;
Image acquisition, the moving image of camera collection brake pedal, and the moving image of gathering transferred to computing machine in real time;
The image pre-service, useless point and noise spot in the moving image of removal brake pedal;
Extract the contour images of brake pedal,, extract the shape of brake pedal in the moving image, obtain the contour images of brake pedal carrying out binary conversion treatment through the pretreated moving image of image;
Extract the unique point of brake pedal, choose the unique point of brake pedal, extract the position of this unique point in the contour images of brake pedal;
Stroke calculates, obtain after the position of unique point in the contour images of brake pedal, the camera parameter of utilizing camera calibration to obtain, calculate the position coordinates of this unique point, the relative position of this unique point changes when obtaining with the brake pedal zero load, promptly obtain the stroke of brake pedal, the time of reference motion image changes, and obtains the movement velocity and the acceleration of brake pedal.
The improvement of advancing of the technical program is:
The described tip point of choosing the unique point of brake pedal for its V-arrangement.
The measurement mechanism of vehicle brake pedal travel of the present invention, critical piece adopts camera head and computing machine, investment cost is few, simple to operate, easy to detect, measuring accuracy is high, and does not need to change brake pedal, has avoided measurement distortion of the prior art or has had the many problems of potential safety hazard.In the measuring method of the present invention, the processing of moving image and the calculating of measurement data are directly finished by computing machine, and is therefore simple to operate, and testing result is directly perceived, reliable.
Description of drawings
Fig. 1 is that the installation of camera reaches the shooting synoptic diagram to brake pedal;
Among the figure: 1, camera; 2, LED lamp; 3, stainless steel strut; 4, brake pedal.
Embodiment
With reference to Fig. 1, in the measurement mechanism of vehicle brake pedal travel, image collecting device can be video camera or camera, and present embodiment adopts camera 1.Camera 1 relies on support to be fixed on the interior stainless steel strut 3 of car in brake pedal 4 left sides, and camera lens is towards brake pedal 4.Brake pedal 4 environment of living in are relatively darker, therefore fixed L ED lamp 2 conduct shooting light sources on camera 1.The side-glance shape of brake pedal 4 is a V-arrangement.
The present embodiment camera adopts culminant star YJS-01 USB2.0 camera, valid pixel 6,000,000, this camera is connected to computing machine by the USB2.0 data line, receive the moving image of brake pedal, the different brake pedal position constantly that obtain by image recognition, just the stroke of brake pedal be can access through geometric transformation, and then the movement velocity and the acceleration of brake pedal calculated.
At the stroke of measuring brake pedal constantly, because the process of driver's operation brake pedal is very fast, therefore, the frequency acquisition of camera must be able to satisfy the collection demand of experimental system, selected camera collection frequency is 25Hz in the present embodiment, and promptly the video camera per second is gathered 25 frame pictures to brake pedal.
In order to realize the measuring method of vehicle brake pedal travel of the present invention, based on the measurement mechanism of above-mentioned vehicle brake pedal travel, image collector is changed to camera, and concrete steps are as follows:
(1) camera and shooting light source are installed
Camera is at first installed camera after selecting and finishing, and camera adopts the column support to be fixed on the interior steel plate of car in brake pedal left side, and support adopts bolt to be connected with steel plate.The camera level is installed, and vertical with brake pedal, the LED lamp is fixed on above the camera, and direction of illumination and camera parallel axes are vertical with the vertical plane of brake pedal.Camera need guarantee distance between camera lens and the brake pedal greater than 20cm when installing, otherwise the driver may run into video camera when the operation brake pedal, cause measurement result that bigger error takes place.
(2) camera calibration
At first make scaling board, uncalibrated image is set on the scaling board, conversion scaling board position, the camera acquisition image utilizes these images to demarcate, and obtains parameters of pick-up head.Be specially: scaling board is made up of square square frame chequered with black and white, that the length of side is 20mm, totally 5 square frames on each direction.Visual range inner conversion scaling board position at camera, allow scaling board towards camera, respectively gather the scaling board image at diverse location, these images are imported among the mathematics manipulation software MATLAB2008b of Math Works company and demarcate, obtain parameters of pick-up head;
The purpose of camera calibration is to obtain parameters of pick-up head, mainly contains: effective focal length f, and principal point o, coefficient of torsion fc and distortion factor kc, these parameters have been reacted the pattern distortion that camera itself is brought, and need use when definite brake pedal physical location.
(3) computer initialization video camera
After the start-up system, utilize the image initial button of image processing software, camera is carried out initialization, initialized purpose is to determine the frequency acquisition of camera, exposure, parameters such as photographic quality, initialization data transfers to camera by the USB2.0 connecting line, camera carries out initialization after receiving initialization directive automatically, returns initialization completion signal after initialization is finished and gives computing machine, and indication can begin image acquisition process.
(4) image acquisition and transmission
The moving image of camera collection brake pedal, and the moving image of gathering transferred to computing machine in real time.After computing machine receives the camera initialization completion signal, display system is ready in image processing software, can begin to gather, the experimenter begins to gather the real time kinematics image of brake pedal by image processing software control video camera, in the gatherer process, the acquisition rate that camera obtains according to initialization, exposure, parameters such as photographic quality are gathered the moving image of brake pedal in real time.If camera breaks down in the time of can't gathering moving image, camera will send the signal that can't gather moving image to computing machine, and this signal will show in image processing software, remind the experimenter to take measures on customs clearance and fix a breakdown.
Camera is in the picture gatherer process, in real time the moving image that collects is sent in the computing machine, the gatherer process of this process of transmitting and moving image is to carry out simultaneously, the moving image of the collection brake pedal that to be camera do not stop with the speed of 25Hz sends to the moving image that collects in the computing machine by the USB2.0 data line simultaneously and uses for the image processing software collection.
(5) image pre-service
Useless point and noise spot in the moving image of removal brake pedal.Image processing software adopts filtering algorithm that the original moving image of brake pedal is carried out pre-service, mainly be to remove the relevant information that has nothing to do with brake pedal in the original moving image, prevent from the profile leaching process in the back to cause the mistake of measurement result because the interference of these irrelevant informations makes a mistake.Image processing software adopts filtering algorithm that original moving image is handled, specific implementation process is for certain point in the moving image of brake pedal, if exist other pixels of subject image around this point, also exist the pixel of subject image around described other pixels, be that these points are continuous, so just think that this point belongs to brake pedal.Opposite, if certain point or certain zonule around do not have other pixels of brake pedal image, then this point or should the zone do not belong to the image of brake pedal is the image of other interference sections, therefore these is put removal.
(6) contour images of extraction brake pedal
To carrying out binary conversion treatment through the pretreated moving image of image, extract the shape of brake pedal in the moving image, obtain the contour images of brake pedal.The purpose that profile extracts is the boundary shape that obtains brake pedal, and the appearance profile of brake pedal is provided for the stroke measurment of follow-up brake pedal.Adopting binarization method that image is carried out profile in the image processing software extracts, so-called binaryzation is to judge according to the gray-scale value of pixel whether this point belongs to brake pedal, if then the value that will put changes 0 into, be that gray scale is 0, with this mark,, then this point is designated as 1 with black if instead certain point does not belong to brake pedal, be that gray scale is 255, use white this mark.After computing was finished in this way to a two field picture, the black in the image partly was the shape of brake pedal.To the two field picture that camera collection arrives, the value of each pixel is the gray-scale value of this point in the image, changes between 0 to 255.In the profile extraction procedure, at first be determined by experiment a threshold value, as 130, gray-scale value and this threshold value with each point in the image of brake pedal compares computing then, if this gray-scale value, thinks then that this point does not belong to brake pedal greater than this threshold value, use white marking, if instead this gray-scale value is less than this threshold value, then thinking changes the time belongs to brake pedal, uses density bullet.
(7) unique point of extraction brake pedal
The tip point of V-arrangement of choosing brake pedal obtains the position of this unique point in the contour images of brake pedal as unique point.Brake pedal is done as a whole, should integral body in the braking procedure have a few and all follow the dead axle rule that rotatablely moves, therefore, the change in location that only need obtain certain point on the brake pedal just can be reacted the motion state of brake pedal, obtains the stroke of brake pedal.
In order to guarantee that image processing software at every turn can both be to a certain definite point on the brake pedal, be that unique point is carried out the stroke that data computation obtains brake pedal, need in the system can be clear and definite definite a certain unique point, operable unique point has three on the brake pedal, comprise upper edge point with driver's sole surface of contact, lower edge point, another one are the pointed points that the V-arrangement brake pedal is positioned at lowest part.Use the pointed of lowest part in the present embodiment,, can cause certain influence measuring accuracy because other two alternative features points are subjected to the influence of driver's foot action easily when practical operation as unique point.Image processing software carries out feature point extraction to the picture that profile extracts after finishing, and concrete extraction algorithm is to judge whether the following image of this unique point also has the pixel of brake pedal; If no, then this point is exactly the needed unique point of system, otherwise is not, continues next pixel is judged calculating.
(8) stroke calculates
Obtain after the position of unique point in the contour images of brake pedal, the camera parameter of utilizing camera calibration to obtain, calculate the position coordinates of this unique point, the relative position of this unique point changes when obtaining with the brake pedal zero load, promptly obtain the stroke of brake pedal, the time of reference motion image changes, and obtains the movement velocity and the acceleration of brake pedal.
Be specially: image processing software obtains after the unique point of brake pedal, writes down this coordinate in moving image, with (x, y) coordinate representation of two axis coordinate systems.Because camera adopts the convex camera lens to gather the moving image of brake pedal, from the real motion image to the transformation relation that exists pattern distortion the moving image that camera collected, this transformation relation represents by parameters of pick-up head that mainly parameters of pick-up head obtains by foregoing camera calibration process.Otherwise, after obtaining the moving image that camera gathers, these parameters according to camera can reversely obtain brake pedal position in practice, because camera is hard-wired, therefore brake pedal in practice the conversion of position directly react the stroke of brake pedal, only need carry out distance calculation, promptly obtain the stroke of brake pedal two positions.
During computing machine actual computation brake-pedal travel, only selected unique point is carried out reverse calculating, obtain this some position in practice, also use coordinate points (X, Y) expression in two axis coordinate systems.When brake pedal is unloaded, determine unique point original position coordinate (X0, Y0), after every frame moving image finished dealing with, obtain unique point position in practice, with (X, Y) expression, at this moment, point (X, Y) with point (X0, Y0) distance between is exactly the stroke of this moment brake pedal, calculate two positions that unique point is continuous, obtain the stroke of this time period, then obtain the speed of this time period inside brake pedal divided by time of this time period, and then calculate acceleration with the inside brake pedal.Computing machine obtains after the stroke of brake pedal, in software window, show in real time, with reference to use, in computing machine, create a Microsoft Excel simultaneously for the experimenter, brake-pedal travel in the experimentation is inserted this Microsoft Excel according to time series, use for experimenter's subsequent analysis.
Claims (2)
1. the measuring method of a vehicle brake pedal travel, based on the measurement mechanism of vehicle brake pedal travel, the measurement mechanism of described vehicle brake pedal travel comprises:
Image collecting device is fixed on brake pedal one side, gathers the moving image of brake pedal; Described image collector is changed to camera; The camera level is installed, and is vertical with brake pedal, and camera need guarantee when installing that distance between camera lens and the brake pedal is greater than 20cm;
Computing machine, be electrically connected image collecting device, receive the moving image of brake pedal, the different brake pedal position constantly that obtain by image recognition, obtain the stroke of brake pedal through geometric transformation, and then calculate the movement velocity and the acceleration of brake pedal;
It is characterized in that described measuring method may further comprise the steps:
Camera calibration is at first made scaling board, and uncalibrated image is set on the scaling board, conversion scaling board position, and the camera collection image utilizes these images to demarcate, and obtains parameters of pick-up head;
Image acquisition, the moving image of camera collection brake pedal, and the moving image of gathering transferred to computing machine in real time;
The image pre-service, useless point and noise spot in the moving image of removal brake pedal;
Extract the contour images of brake pedal,, extract the shape of brake pedal in the moving image, obtain the contour images of brake pedal carrying out binary conversion treatment through the pretreated moving image of image;
Extract the unique point of brake pedal, choose the unique point of brake pedal, extract the position of this unique point in the contour images of brake pedal;
Stroke calculates, obtain after the position of unique point in the contour images of brake pedal, the camera parameter of utilizing camera calibration to obtain, calculate the position coordinates of this unique point, the relative position of this unique point changes when obtaining with the brake pedal zero load, promptly obtain the stroke of brake pedal, the time of reference motion image changes, and obtains the movement velocity and the acceleration of brake pedal.
2. the measuring method of a kind of vehicle brake pedal travel according to claim 1, the described tip point of choosing the unique point of brake pedal for its V-arrangement.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2009100221732A CN101545759B (en) | 2009-04-24 | 2009-04-24 | Vehicle brake pedal travel measuring method |
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| CN2009100221732A CN101545759B (en) | 2009-04-24 | 2009-04-24 | Vehicle brake pedal travel measuring method |
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| CN101545759B true CN101545759B (en) | 2011-03-16 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107472233A (en) * | 2016-12-23 | 2017-12-15 | 宝沃汽车（中国）有限公司 | Position calibration method, system and the vehicle of brake pedal |
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| CN102269656B (en) * | 2010-08-04 | 2013-08-14 | 长安大学 | Measuring apparatus for operation behavior on pedal by driver and monitoring method thereof |
| CN102826008A (en) * | 2012-09-15 | 2012-12-19 | 李良杰 | System for monitoring feet operation of driver |
| CN102874173A (en) * | 2012-10-21 | 2013-01-16 | 李良杰 | Driver feet operation monitoring system based on thermal imagery |
| CN102981009A (en) * | 2012-11-20 | 2013-03-20 | 北京工业大学 | Indirect speed measuring device |
| CN103017719B (en) * | 2012-12-07 | 2015-04-29 | 奇瑞汽车股份有限公司 | Measuring instrument for pedal motion trails |
| CN104677297A (en) * | 2015-03-17 | 2015-06-03 | 上海通工汽车零部件有限公司 | Automatic detector for work stroke of automobile pedal and detection method of automatic detector |
| CN104913809A (en) * | 2015-06-25 | 2015-09-16 | 苏州石丸英合精密机械有限公司 | Pedal in-place sensing device of automobile brake-accelerator pedal detection machine |
| CN106828503B (en) * | 2017-02-15 | 2018-11-30 | 武汉理工大学 | A kind of operator brake behavior and state real-time identification method |
| CN106950050B (en) * | 2017-03-24 | 2018-12-21 | 安徽江淮汽车集团股份有限公司 | Brake-pedal travel measuring device |
| CN107351836B (en) * | 2017-07-11 | 2019-12-03 | 浙江大学常州工业技术研究院 | A kind of pedal scaling method of four-wheel electric motor car |
| CN107966232B (en) * | 2017-11-24 | 2020-04-24 | 中国特种设备检测研究院 | Method and system for monitoring performance of hoisting equipment brake based on machine vision |
| CN114312694B (en) * | 2021-12-27 | 2022-11-25 | 大连工业大学 | Automobile acceleration and deceleration control system and method based on foot posture control |
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2009
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107472233A (en) * | 2016-12-23 | 2017-12-15 | 宝沃汽车（中国）有限公司 | Position calibration method, system and the vehicle of brake pedal |
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